Document:

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                                                                    EXHIBIT 10.2

                                    GUARANTEE

     GUARANTEE dated as of March 2, 2001 (this "Guarantee") made by IMMUNEX
                                                ---------
CORPORATION, a Washington corporation ("Immunex") and IMMUNEX MANUFACTURING
                                        -------
CORPORATION, a Washington corporation (together with Immunex, individually and
collectively, the "Guarantor"), in favor of Immunex Real Estate Trust 2001 (the
                   ---------
"Lessor"), Immunex Funding Corp., a Delaware corporation ("SPC"), the Investors,
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and Chase Manhattan Bank, as Administrative Agent for SPC (the Lessor, the
Investors, SPC, Chase Manhattan Bank, as Administrative Agent for SPC, and their
respective successors and assigns, collectively known as the "Beneficiaries").
                                                              -------------

                             Preliminary Statement
                             ---------------------

     Pursuant to the SPC Loan Agreement, SPC has agreed to make loans (the "SPC
                                                                            ---
Loans") to the Lessor upon the terms and conditions set forth therein, to be
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evidenced by notes issued by the Lessor under the SPC Loan Agreement. The Lessor
has entered into the SPC Loan Agreement for the purpose of facilitating the
financing, with the proceeds of the SPC Loans, of the acquisition of a leasehold
interest in the Land and the construction of Improvements thereon, which Land
and Improvements shall, in turn, be leased to the Lessee.

     The SPC Loans will be made from time to time at the request of the
Construction Agent in consideration for the agreement of the Construction Agent,
for the benefit of the Lessor, to perform its obligations under the Agency
Agreement. It is a condition precedent to the obligation of SPC to make its SPC
Loans to the Lessor under the SPC Loan Agreement and for the Investors to make
their Contributions under the Participation Agreement that the Guarantor shall
have executed and delivered this Guarantee for the ratable benefit of the
Beneficiaries.

     The Guarantor wishes to induce (i) SPC to make the SPC Loans and enter into
the SPC Loan Agreement and the other Operative Agreements to which it is a party
and (ii) the Investors to make the Investor Contributions and enter into the
Participation Agreement (referred to below) and the other Operative Agreements
to which they are party.

     NOW, THEREFORE, in consideration of the premises contained herein and to
induce (i) SPC to make the SPC Loans and enter into the SPC Loan Agreement and
the other Operative Agreements to which it is a party and (ii) the Investors to
make the Investor Contributions and enter into the Participation Agreement and
the other Operative Agreements to which they are a party, the Guarantor hereby
agrees for the ratable benefit of the Beneficiaries as follows:
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     1. Defined Terms. (a) Capitalized terms not otherwise defined herein shall
        -------------
have the meanings set forth on Annex A to the Participation Agreement dated as
of the date hereof among Immunex, Immunex Funding Corp., as SPC, The Chase
Manhattan Bank, as Administrative Agent, as Collateral Agent and as Agent Bank,
Immunex Real Estate Trust 2001, the Investors party thereto, the Banks party
thereto, and Wilmington Trust Company.

     (b) As used herein, the following terms shall have the following meanings:

          "Contribution Obligations" means the collective reference to the
           ------------------------
outstanding amount of the Investor Contributions and the Investor Yield with
respect thereto and all rights of the Investors to receive distributions under
the Trust Agreement and any of the other Operative Agreements.

          "Guaranteed Obligations" means the collective reference to (i) the
           ----------------------
Note Obligations and (ii) the Contribution Obligations and, with respect to each
such obligation, interest accruing thereon at the applicable rate provided in
the Operative Agreements after maturity and interest accruing at the then
applicable rate provided in the Operative Agreements after the filing of any
petition in bankruptcy, or the commencement of an insolvency, reorganization or
like proceeding, whether or not a claim for post-filing or post-petition
interest is allowed in such proceeding and whether such obligations are direct
or indirect, absolute or contingent, due or to become due, or now existing or
hereinafter incurred, which may arise, under, out of or in connection with any
of the Operative Agreements, any other document made, delivered or given in
connection therewith, in each case whether on account of principal, interest,
Investor Contributions or Investor Yield, reimbursement obligations, fees,
indemnities, costs, expenses, or payment obligations (including, without
limitation, all fees and disbursements of counsel to any of the Beneficiaries).

          "Note Obligations" means the collective reference to the unpaid
           ----------------
principal of and interest on the SPC Loans and the SPC Notes and all other
payment obligations and liabilities of the Lessor to the Administrative Agent
and SPC under the SPC Notes, the SPC Loan Agreement and any of the other
Operative Agreements.

     2.  Guarantee. (a) Subject to the provisions of paragraph 2(b) and (c), the
         ---------
Guarantor hereby unconditionally and irrevocably guarantees to the Beneficiaries
and their respective successors, endorsees, transferees and assigns the prompt
and complete payment when due (whether at the stated maturity, by acceleration
or otherwise) of the Guaranteed Obligations.

     (b) Anything to the contrary notwithstanding, (i) if (A) a Construction
Risk Event has occurred, (B) no other Lease Event of Default has occurred and is
continuing at such time, and (C) the Construction Agent performs its obligations
under Section 5.4(a) of the Agency Agreement, then the obligations of the
Guarantor hereunder shall be limited to the Guaranteed Obligations in the amount
of the Non-Completion Amount and all other amounts owing by Lessee or
Construction Agent under Section 5.4(a) of the Agency Agreement, and (ii)(A) if
no Lease Event of Default, or on the Maturity Date, no Lease Default has
occurred and is continuing, the obligations of the Guarantor hereunder shall be
limited to the unpaid principal of and interest on the Tranche A SPC Notes and
(B) if any (x) Lease Event of Default or (y) on the

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Maturity Date, any Lease Default has occurred and is continuing, the Guarantor
shall be liable for the Guaranteed Obligations.

     (c) Without affecting any of the Construction Agent's obligations under
Section 5.4(a) of the Agency Agreement and the Guarantor's obligations hereunder
with respect thereto, anything else herein to the contrary notwithstanding,
during the Construction Period the Lessee shall not be liable for any Note
Obligations hereunder.

     (d) The Guarantor further agrees to pay any and all expenses (including,
without limitation, fees and disbursements of counsel) which may be paid or
incurred by the Administrative Agent, Collateral Agent or any Beneficiary in
enforcing, or obtaining advice of counsel in respect of, any rights with respect
to, or collecting, any or all of the Guaranteed Obligations and/or enforcing any
rights with respect to, or collecting against, the Guarantor under this
Guarantee. This Guarantee shall remain in full force and effect until the
Guaranteed Obligations and all amounts owing hereunder are paid in full,
notwithstanding that from time to time prior thereto the Lessor may be free from
any Guaranteed Obligations.

     (e) The Guarantor agrees that the Guaranteed Obligations may at any time
and from time to time exceed the amount of the liability of the Guarantor
hereunder without impairing this Guarantee or affecting the rights and remedies
of Collateral Agent or any Beneficiary hereunder with respect to the amount of
the liability of Guarantor.

     (f) No payment or payments made by the Lessor, any Guarantor or any other
Person or received or collected by Collateral Agent or any Beneficiary from the
Lessor, a Guarantor or any other Person by virtue of any action or proceeding or
any set-off or appropriation or application at any time or from time to time in
reduction of or in payment of the Guaranteed Obligations shall be deemed to
modify, reduce, release or otherwise affect the liability of the Guarantor
hereunder which shall, notwithstanding any such payment or payments remain
liable for the Guaranteed Obligations up to the maximum liability of such
Guarantor as set forth in this Section 2 until the Guaranteed Obligations and
all amounts owing hereunder are paid in full.

     (g) The Guarantor agrees that whenever, at any time, or from time to time,
it shall make any payment to anything in this Guarantee (including this Section
2) or in any other Operative Agreement to the contrary notwithstanding, any
payment made by the Lessee, Construction Agent or the Guarantor to the Lessor in
accordance with the Operative Agreements shall satisfy and discharge the
obligations of the Guarantor hereunder to the extent of such payment; and
Guarantor shall have no obligation or liability to the Collateral Agent or any
Beneficiary on account of its liability hereunder, it will notify Collateral
Agent in writing that such payment is made under this Guarantee for such
purpose.

     (h) The obligations of each entity comprising Guarantor hereunder shall be
joint and several.

     3. Right of Set-off. In addition to any rights now or hereafter granted
        ----------------
under applicable law or otherwise, and to the extent not prohibited by
applicable law, and not by way of limitation of any such rights, upon the
occurrence and during the continuance of an Event of

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Default, Collateral Agent and each Beneficiary is hereby authorized at any time
or from time to time, without presentment, demand, protest or other notice of
any kind to the Lessor, the Guarantor or to any other Person, any such notice
being hereby expressly waived, to set off and to appropriate and apply any and
all deposits (general or special) and any other Indebtedness at any time held or
owing by Collateral Agent or such Beneficiary (including, without limitation, by
branches and agencies of Collateral Agent or such Beneficiary wherever located)
to or for the credit or the account of the Guarantor against and on account of
the obligations and liabilities of the Guarantor hereunder (subject to the
limitations herein), and all other claims of any nature or description arising
out of or connected with this Guarantee or any other Operative Agreement,
provided that all notices and cure periods have been provided to Lessor as
required under the applicable Operative Agreement(s), but irrespective of
whether Collateral Agent or such Beneficiary shall have made any demand
hereunder and although said obligations, liabilities or claims, or any of them,
shall be contingent or unmatured. Collateral Agent and each Beneficiary agrees
promptly to notify Guarantor after any such set off and application made by
Collateral Agent or such Beneficiary; provided that failure to give such notice
shall not affect the validity of such set-off and application.

           4. No Subrogation. Notwithstanding any payment or payments made by
              --------------
the Guarantor hereunder or any set-off or application of funds of the Guarantor
by any Beneficiary, the Guarantor shall not be entitled to exercise or enforce
any subrogation rights of Collateral Agent or any Beneficiary against the Lessor
or any other Person or any collateral security or guarantee or right of offset
held by Collateral Agent or any Beneficiary for the payment of the Guaranteed
Obligations, nor shall the Guarantor seek or be entitled to seek any
contribution or reimbursement from the Lessor or any other Person in respect of
payments made by the Guarantor hereunder, until all amounts owing to Collateral
Agent and the Beneficiaries by the Lessor on account of the Guaranteed
Obligations and all amounts owing hereunder are paid in full. If any amount
shall be paid to the Guarantor on account of such subrogation rights at any time
when all of the Guaranteed Obligations and all amounts owing hereunder shall not
have been paid in full, such amount shall be held by the Guarantor in trust for
Collateral Agent and the Beneficiaries, segregated from other funds of the
Guarantor, and shall, forthwith upon receipt by the Guarantor, be turned over to
Collateral Agent in the exact form received by the Guarantor (duly indorsed by
the Guarantor to Collateral Agent, if required), to be applied against the
Guaranteed Obligations, whether matured or unmatured, in such order as set forth
in Section 13 of the Participation Agreement.

           5. Amendments, etc. with respect to the Guaranteed Obligations;
              -----------------------------------------------------------
Waiver of Rights. The Guarantor shall remain obligated hereunder notwithstanding
----------------
that, without any reservation of rights against the Guarantor and without notice
to or further assent by the Guarantor, any demand for payment of any of the
Guaranteed Obligations made by Collateral Agent or any Beneficiary may be
rescinded by such party and any of the Guaranteed Obligations continued, and the
Guaranteed Obligations, or the liability of any other party upon or for any part
thereof, or any collateral security or guarantee therefor or right of offset
with respect thereto, may, from time to time in accordance with the respective
terms thereof, in whole or in part, be renewed, extended, amended, modified,
accelerated, compromised, waived, surrendered or released by Collateral Agent or
any Beneficiary, and the SPC Loan Agreement, the Participation Agreement and the
other Operative Agreements may be amended, modified, supplemented or terminated,
in whole or in part, from time to time, and any collateral security, guarantee
or right

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of offset at any time held by Collateral Agent or any Beneficiary for the
payment of the Guaranteed Obligations may be sold, exchanged, waived,
surrendered or released. Neither Collateral Agent nor any Beneficiary shall have
any obligation to protect, secure, perfect or insure any Lien at any time held
by it as security for the Guaranteed Obligations or for this Guarantee or any
property subject thereto. When making any demand hereunder against the
Guarantor, Collateral Agent or any Beneficiary may, but shall be under no
obligation to, make a similar demand on the Lessor or any other guarantor, and
any failure by Collateral Agent or any Beneficiary to make any such demand or to
collect any payments from the Lessor or any other guarantor or any release of
the Lessor or such other guarantor shall not relieve the Guarantor from its
obligations under this Guarantee, and shall not impair or affect the rights and
remedies, express or implied, or as a matter of law, of Collateral Agent or any
Beneficiary against the Guarantor. For the purposes hereof "demand" shall
include the commencement and continuance of any legal proceedings.

           6. Guarantee Absolute and Unconditional. The Guarantor waives any and
              ------------------------------------
all notice of the creation, renewal, extension or accrual of any of the
Guaranteed Obligations and notice of or proof of reliance by Collateral Agent or
any Beneficiary upon this Guarantee or acceptance of this Guarantee; the
Guaranteed Obligations, and any of them, shall conclusively be deemed to have
been created, contracted or incurred, or renewed, extended, amended or waived,
in reliance upon this Guarantee; and all dealings between the Lessor and the
Guarantor, on the one hand, and Collateral Agent and the Beneficiaries, on the
other hand, likewise shall be conclusively presumed to have been had or
consummated in reliance upon this Guarantee. The Guarantor waives diligence,
presentment, protest, demand for payment and notice of default or nonpayment to
or upon the Lessor or the Guarantor with respect to the Guaranteed Obligations.
The Guarantor understands and agrees that this Guarantee shall be construed as a
continuing, absolute and unconditional guarantee and surety of payment without
regard to (a) the validity, regularity or enforceability of the SPC Loan
Agreement or any other Operative Agreement, any of the Guaranteed Obligations or
any other collateral security therefor or guarantee or right of offset with
respect thereto at any time or from time to time held by Collateral Agent or any
Beneficiary, (b) any defense, set-off or counterclaim (other than a defense of
payment or performance) which may at any time be available to or be asserted by
the Lessor or the Guarantor against Collateral Agent or any Beneficiary, or (c)
any other circumstance whatsoever (with or without notice to or knowledge of the
Lessor or the Guarantor) which constitutes, or might be construed to constitute,
an equitable or legal discharge of the Lessor for the Guaranteed Obligations, or
of the Guarantor under this Guarantee, in bankruptcy or in any other instance.
When pursuing its rights and remedies hereunder against the Guarantor,
Collateral Agent and any Beneficiary may, but shall be under no obligation to,
pursue such rights and remedies as it may have against the Lessor or any other
Person or against any collateral security or guarantee for the Guaranteed
Obligations or any right of offset with respect thereto, and any failure by
Collateral Agent or any Beneficiary to pursue such other rights or remedies or
to collect any payments from the Lessor or any such other Person or to realize
upon any such collateral security or guarantee or to exercise any such right of
offset, or any release of the Lessor or any such other Person or any such
collateral security, guarantee or right of offset, shall not relieve the
Guarantor of any liability hereunder, and shall not impair or affect the rights
and remedies, whether express, implied or available as a matter of law, of
Collateral Agent and the Beneficiaries against the Guarantor. This Guarantee
shall remain in full force and effect and be binding in accordance with and to
the extent of its terms upon the Guarantor and the successors and assigns
thereof, and

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shall inure to the benefit of Collateral Agent and the Beneficiaries, and their
respective successors, indorsees, transferees and assigns, until all the
Guaranteed Obligations and the obligations of the Guarantor under this Guarantee
shall have been satisfied by payment in full, notwithstanding that from time to
time during the term of the SPC Loan Agreement, Lease and other Operative
Agreements the Lessor may be free from any Guaranteed Obligations.

           7. Reinstatement. This Guarantee shall continue to be effective, or
              -------------
be reinstated, as the case may be, if at any time payment, or any part thereof,
of any of the Guaranteed Obligations is rescinded or must otherwise be restored
or returned by Collateral Agent or any Beneficiary upon the insolvency,
bankruptcy, dissolution, liquidation or reorganization of the Lessor or the
Guarantor, or upon or as a result of the appointment of a receiver, intervenor
or conservator of, or trustee or similar officer for, the Lessor or the
Guarantor or any substantial part of its property, or otherwise, all as though
such payments had not been made.

           8. Payments. The Guarantor hereby guarantees that payments hereunder
              --------
will be paid to Collateral Agent without set-off or counterclaim in Dollars at
the office of Collateral Agent located at 450 West 33rd Street, New York, New
York 10001. If demand is made for payment under this Guarantee at or prior to
11:00 a.m. Eastern Standard Time on a Business Day, payment shall be due
hereunder on or before the close of such Business Day; otherwise, payment shall
be due before the close of the next succeeding Business Day after such demand is
made.

           9. Affirmative Covenants of the Guarantor. Guarantor hereby covenants
              --------------------------------------
and agrees that so long as this Guarantee is in effect and until the SPC Loan
Commitments and the Investor Contribution Commitments have terminated and the
Guaranteed Obligations and all amounts owing hereunder are paid in full the
Guarantor will:

          9.1   Financial Statements.  Furnish to the Collateral Agent:
          --------------------------

          (a) as soon as available for distribution to shareholders and
          creditors generally, but in any event within 120 days after the end of
          each fiscal year of Immunex, a copy of the consolidated balance sheet
          of Immunex and its consolidated Subsidiaries, as of the end of such
          fiscal year and the related consolidated statements of income and
          retained earnings and of cash flows for such fiscal year, setting
          forth in each case in comparative form the figures for the previous
          fiscal year, reported on without a "going concern" or like
          qualification or exception, or qualification arising out of the scope
          of the audit, by Ernst & Young or other independent certified public
          accountants of nationally recognized standing and reasonably
          acceptable to the Collateral Agent;

          (b) as soon as available for distribution to shareholders and
          creditors generally, but in any event within 90 days after the end of
          each fiscal year of Immunex, a copy of the unaudited consolidated
          balance sheet of Immunex and its consolidated Subsidiaries, as at the
          end of such year, and the related unaudited consolidated statements of
          income and retained earnings and of cash flows for such year, in each
          case setting forth in comparative form the figures for the
          corresponding

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          period of the previous year and the figures for such period as shown
          on the budgets of Immunex for such year; and

          (c) as soon as available, but in any event not later than 45 days
          after the end of each of the first three quarterly periods of each
          fiscal year of Immunex, the unaudited consolidated balance sheet of
          Immunex and its consolidated Subsidiaries, as at the end of such
          quarter, and the related unaudited consolidated statements of income
          and retained earnings and of cash flows of Immunex and its
          consolidated Subsidiaries, for such quarter and the portion of the
          fiscal year through the end of such quarter, setting forth in each
          case in comparative form the figures for the corresponding period of
          the previous fiscal year, certified by a Responsible Officer of
          Immunex as being fairly stated in all material respects when
          considered in relation to the consolidated financial statements of
          Immunex and its consolidated Subsidiaries, (subject to normal year-end
          audit adjustments), and in each case setting forth in comparative form
          the figures for such periods as shown on the budgets of such Person
          for such year; and

          (d) as soon as available, copies of its Current SEC Reports, if any;

all such financial statements to be complete and correct in all material
respects and to be prepared in reasonable detail and in accordance with GAAP
applied consistently throughout the periods reflected therein and with prior
periods (except as approved by such accountants or officer, as the case may be,
and disclosed therein).

          9.2   Certificates; Other Information. Furnish to the Collateral
          -------------------------------------
Agent:

          (a) concurrently with the delivery of the financial statements
          referred to in Section 9.1(a), or as a component thereof, a
          certificate of the independent certified public accountants reporting
          on such financial statements stating that in making the examination
          necessary therefor no knowledge was obtained of any Default or Event
          of Default, except as specified in such certificate;

          (b) concurrently with the delivery of the financial statements
          referred to in Sections 9.1(a) and 9.1(c), a certificate of a
          Responsible Officer of Immunex stating that, to the best of such
          Responsible Officer's knowledge, Guarantor during such period has
          observed or performed all of its covenants and other agreements, and
          satisfied every material condition, contained in this Guarantee and
          the other Operative Agreements to which it is a party to be observed,
          performed or satisfied by it, and that such Responsible Officer has
          obtained no knowledge of any Default or Event of Default except as
          specified in such certificate;

          (c) (i) within five days after the same are sent, copies of all
          financial statements and reports which Immunex, if at such time any
          class of Immunex's securities are held by the public, sends to its
          stockholders generally, or, if otherwise, such financial statements
          and reports as are made generally available to the public, and (ii)
          within five days after the same are filed, copies of all financial
          statements and

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          reports which Immunex may make to, or file with, the Securities and
          Exchange Commission or any successor or analogous Governmental
          Authority;

          (d) promptly, such additional financial and other information as the
          Beneficiaries or the Collateral Agent may from time to time reasonably
          request.

          9.3 Payment of Obligations. Pay, discharge or otherwise satisfy at or
          --------------------------
before maturity or before they become delinquent, as the case may be, all its
material obligations of whatever nature, except where the amount or validity
thereof is currently being contested in good faith by appropriate proceedings
and reserves in conformity with GAAP with respect thereto have been provided on
the books of Guarantor or any Subsidiary of Guarantor, as the case may be.

          9.4 Conduct of Business and Maintenance of Existence. Continue to
          ----------------------------------------------------
engage in business in the same general type of industry or industries in which
its business is now conducted by it, and, in conjunction therewith, in any
industry or industries complementary thereto as reasonably determined by
Immunex, and preserve, renew and keep in full force and effect its corporate
existence and take all reasonable action to maintain all rights, privileges and
franchises necessary or desirable in the normal conduct of its business except
as otherwise permitted pursuant to Section 9.5, provided, that Immunex may
re-incorporate under the laws of the State of Delaware in accordance with
applicable Legal Requirements and upon thirty (30) days prior written notice to
Collateral Agent; comply with all Contractual Obligations and Legal Requirements
except to the extent that failure to comply therewith would not, in the
aggregate, reasonably be expected to have a Material Adverse Effect.

          9.5 Maintenance of Property; Insurance. Guarantor will, and will
          --------------------------------------
cause each of its consolidated Subsidiaries to, (a) keep and maintain all
property material to the conduct of its business in good working order and
condition, casualty, condemnation and ordinary wear and tear excepted, and
promptly repair or replace such property following any damage thereto, and (b)
maintain, with financially sound and reputable insurance companies, insurance in
such amounts and against such risks as are customarily maintained by companies
engaged in the same or similar businesses operating in the same or similar
locations.

          9.6 Inspection of Property; Books and Records; Discussions. Keep
          ----------------------------------------------------------
proper books of records and account in which full, true and correct entries in
conformity with GAAP and all Legal Requirements shall be made of all dealings
and transactions in relation to its business and activities; and permit
representatives of Collateral Agent to visit and inspect any of its properties
and examine and make abstracts from any of its books and records at any
reasonable time and as often as may reasonably be desired in accordance with
Section 10.3 of the Lease, and to discuss the business, operations, properties
and financial and other condition of Guarantor and Subsidiaries of Guarantor
with officers and employees of Guarantor and Subsidiaries of Guarantor and with
its independent certified public accountants; provided, however, that no such
visit, inspection or examination or discussion shall unreasonably disrupt or
interfere with normal operations of Guarantor or any of its Subsidiaries and any
such representatives of the Beneficiaries and the Collateral Agent shall be
accompanied by a Responsible Officer of Guarantor. No failure to comply with any
request for the exercise of rights hereunder shall be

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cause for any Event of Default unless such request is submitted in writing to
Guarantor with reference to this Section 9.6.

           9.7   Notices. Promptly give notice to the Beneficiaries and the
           -------------
Collateral Agent of:

           (a) the occurrence of any Default or Event of Default of which
           Guarantor has actual knowledge;

           (b) any (i) default or event of default by Guarantor or any of its
           Subsidiaries under or with respect to any of their respective
           Contractual Obligations in any respect which, if not cured, would
           reasonably be expected to have a Material Adverse Effect, or to
           Guarantor's knowledge any default or event of default by any third
           party under or with respect to any Contractual Obligation of said
           third party with Guarantor or any of its Subsidiaries in a respect
           which, if not cured, would reasonably be expected to have a Material
           Adverse Effect or (ii) litigation, investigation or proceeding of
           which Guarantor has actual knowledge which may exist at any time
           between Guarantor or any Subsidiary of Guarantor and any Governmental
           Authority, which in either case, if not cured or if adversely
           determined, as the case may be, would reasonably be expected to have
           a Material Adverse Effect;

           (c) any litigation or proceeding affecting Guarantor or any
           Subsidiary of Guarantor of which Guarantor has actual knowledge in
           which the amount involved is reasonably anticipated by Guarantor to
           exceed $15,000,000 or more and not covered by insurance or in which
           injunctive or similar relief is sought and which if adversely
           determined would reasonably be expected to have a Material Adverse
           Effect;

           (d) the following events, as soon as possible and in any event within
           30 days after Guarantor has actual knowledge thereof: (i) the
           occurrence or expected occurrence of any Reportable Event with
           respect to any Plan, or any withdrawal from, or the termination,
           Reorganization or Insolvency of any Multiemployer Plan or (ii) the
           institution of proceedings or the taking of any other action by the
           PBGC or Guarantor, any Commonly Controlled Entity with respect to the
           termination of any Single Employer Plan; and

           (e) (i) a development or event which has had or would reasonably be
           expected to result in the Fixed Charge Ratio being less than 1.0 to
           1, or (ii) any action by the Food and Drug Administration ("FDA")
                                                                       ---
           which causes Immunex to operate under a consent decree, or (iii) any
           action by the FDA which causes Immunex to cease production of Enbrel.

Each notice pursuant to this subsection shall be accompanied by a statement of a
Responsible Officer setting forth details of the occurrence referred to therein
and stating what action Guarantor proposes to take with respect thereto.

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           9.8 Environmental Laws. (a) Comply in all material respects with, and
           ----------------------
undertake all reasonable efforts to ensure compliance by all tenants and
subtenants, if any, with, all Environmental Laws and obtain and comply in all
material respects with and maintain, and undertake all reasonable efforts to
ensure that all tenants and subtenants obtain and comply with and maintain, any
and all licenses, approvals, registrations or permits required by Environmental
Laws, and upon discovery of any non-compliance or suspected non-compliance,
undertake all reasonable efforts to attain material compliance;

           (b) Conduct and complete all investigations, studies, sampling and
testing, and all remedial, removal and other actions required under
Environmental Laws and promptly comply in all material respects with all lawful
orders and directives of all Governmental Authorities respecting Environmental
Laws, except to the extent that the failure to so conduct, complete or take such
actions, or to comply with such orders and directives, would not in the
aggregate reasonably be expected to have a Material Adverse Effect;

           (c) Defend, indemnify and hold harmless the Lessor, the Beneficiaries
and the Collateral, and their respective employees, agents, officers and
directors, from and against any claims, demands, penalties, fines, liabilities,
settlements, damages, costs and expenses of whatever kind or nature known or
unknown, contingent or otherwise, arising out of, or in any way relating to the
violation of or noncompliance with any Environmental Laws applicable to the real
property owned or operated by Guarantor or any Subsidiary of Guarantor, or any
orders, requirements or demands of Governmental Authorities related thereto,
including, without limitation, reasonable attorney's and consultant's fees,
investigation and laboratory fees, court costs and litigation expenses, except
to the extent that any of the foregoing arise out of the gross negligence or
willful misconduct of the party seeking indemnification therefore; and

           (d) Maintain a program to identify and promote substantial compliance
with and to minimize prudently any liabilities or potential liabilities under
any Environmental Law that may affect Guarantor or any of its Subsidiaries.

           9.9 Subsequent Guarantees. Immunex shall cause each Subsidiary of
           -------------------------
Immunex for which the aggregate value of all assets owned by such Subsidiary is
or becomes greater than the lesser of (x) five percent (5%) of Total Assets as
of the last day of the immediately preceding fiscal quarter of Immunex, (y) five
percent (5%) of Total Revenues for the twelve (12) month period ended on the
immediately preceding fiscal quarter, and (z) five percent (5%) of EBITDA
(without giving effect to this sentence) for the twelve (12) month period ended
on the immediately preceding fiscal quarter, to execute an amendment to this
Guarantee, whereby such Subsidiary becomes a party hereto promptly after the
later of (i) the date on which such Subsidiary becomes a Subsidiary of Immunex
and (ii) the date on which such Subsidiary's assets attain an aggregate value in
excess of the lesser of (x) five percent (5%) of Total Assets as of the last day
of the immediately preceding fiscal quarter of Immunex, (y) five percent (5%) of
Total Revenues for the twelve (12) month period ended on the immediately
preceding fiscal quarter, and (z) five percent (5%) of EBITDA (without giving
effect to this sentence) for the twelve (12) month period ended on the
immediately preceding fiscal quarter; provided, that each Person required to
                                      --------  ----
become a party hereto by this Section 9.9 which becomes a Subsidiary of Immunex
after the date hereof shall only be required to become a party to the extent not
prohibited by such Person's existing contractual obligations in the event that
such contractual obligations existed at

                                       10
<PAGE>

the time such Person became a Subsidiary and were not created in anticipation
thereof. If at any time after such Person becomes a Subsidiary of Immunex any
such contractual prohibition ceases to exist, then such Subsidiary shall be
required to become a party to this Guarantee as provided above in this Section
9.9.

           10.  Negative Covenants. Immunex hereby agrees that so long as this
                ------------------
Guarantee is in effect and until the SPC Loan Commitments and the Investor
Contribution Commitments have terminated and the Guaranteed Obligations and all
amounts owing hereunder are paid in full, Immunex shall not, directly or
indirectly:

          10.1  Financial Condition Covenants.
          -----------------------------------

          (a)   Leverage Ratio. Permit the Leverage Ratio at any time to be
                --------------
greater than 2.0 to 1.0.

          (b)   Fixed Charge Ratio. Permit the Fixed Charge Ratio for the four
                ------------------
          (4) consecutive fiscal quarters of Immunex ending with any fiscal
          quarter set forth below to be less than the ratio set forth opposite
          such fiscal quarter:

<TABLE>
<CAPTION>
                               Four Fiscal Quarters              Fixed Charge Ratio
                               --------------------              ------------------
                                        Ended
                                        -----
                           -------------------------------- ----------------------------
                           <S>                              <C>
                           December 31, 2001                1.75 to 1.0
                           -------------------------------- ----------------------------
                           December 31, 2002                1.75 to 1.0
                           -------------------------------- ----------------------------
                           December 31, 2003                2.0 to 1.0
                           -------------------------------- ----------------------------
                           December 31, 2004                2.0 to 1.0
                           -------------------------------- ----------------------------
                           December 31, 2005                3.0 to 1.0
                           -------------------------------- ----------------------------
                           December 31, 2006                3.0 to 1.0
                           -------------------------------- ----------------------------
                           December 31, 2007                3.0 to 1.0
                           -------------------------------- ----------------------------
                           December 31, 2008                3.0 to 1.0
                           -------------------------------- ----------------------------
</TABLE>

          10.2 Limitation on Liens. Create, incur, assume or suffer to exist any
          ------------------------
Lien upon any of its property, assets or revenues (other than the Property),
whether now owned or hereafter acquired, except for Permitted Encumbrances and
the following:

          (a) Liens for taxes not yet due or which are being contested in good
          faith by appropriate proceedings, provided that adequate reserves with
          respect thereto are maintained on the books of Immunex or any
          Subsidiary of Immunex, as the case may be, in conformity with GAAP;

                                       11
<PAGE>

          (b) carriers', warehousemen's, mechanics', materialmen's, repairmen's
          or other like Liens arising in the ordinary course of business which
          are not overdue for a period of more than 60 days or which are being
          contested in good faith by appropriate proceedings;

          (c) Liens of any of the types referred to in clause (b) above that
          have been bonded for not less than the full amount in dispute (or as
          to which other security arrangements satisfactory to the Agent have
          been made), which bonding (or arrangements) shall comply with
          applicable Legal Requirements, and shall have effectively stayed any
          execution or enforcement of such Liens;

          (d) Liens arising out of judgments or awards with respect to which
          appeals or other proceedings for review are being prosecuted in good
          faith and for the payment of which adequate reserves have been
          provided as required by GAAP or other appropriate provisions have been
          made, so long as such proceedings have the effect of staying the
          execution of such judgments or awards;

          (e) Liens in favor of municipalities to the extent agreed to by the
          Lessor or permitted under the Participation Agreement or other
          Operative Agreements;

          (f) rights of any sublessee or assignee under a sublease or an
          assignment expressly permitted by the terms of the Lease for no longer
          than the duration of the Lease;

          (g) pledges or deposits in connection with workers' compensation,
          unemployment insurance and other social security legislation and
          deposits securing liability to insurance carriers under insurance or
          self insurance arrangements;

          (h) deposits to secure the performance of bids, trade contracts (other
          than for borrowed money), leases, statutory obligations, surety and
          appeal bonds, performance bonds and other obligations of a like nature
          incurred in the ordinary course of business;

          (i) easements, rights-of-way, restrictions and other similar
          encumbrances incurred in the ordinary course of business which, in the
          aggregate, are not substantial in amount and which do not in any case
          materially detract from the value of the property subject thereto or
          materially interfere with the ordinary conduct of the business of
          Immunex or any of its Subsidiaries;

          (j) Liens in favor of customs and revenue authorities arising as a
          matter of law to secure payment of custom duties in connection with
          the importation of goods so long as such Liens attach only to the
          imported goods;

          (k) Liens now or hereafter granted in favor of the Administrative
          Agent, SPC, the Collateral Agent or other Person pursuant to the
          Operative Agreements; and

                                       12
<PAGE>

          (l) Liens not otherwise permitted in clauses (a)-(k) above securing
          Indebtedness not exceeding, when taken together with the aggregate
          value of the assets which are subject to arrangements with any Person
          where Immunex or any of the Subsidiaries of Immunex is the lessee of
          real or personal property which has been or is to be sold or
          transferred by Immunex or such Subsidiary to such Person or to any
          other Person to whom funds have been or are to be advanced by such
          Person on the security of such property or rental obligations of
          Immunex or such Subsidiary, thirty-five percent (35%) of Total Assets.

          10.3 Limitations on Fundamental Changes. Enter into any merger,
          ---------------------------------------
consolidation or amalgamation, or liquidate, wind up or dissolve itself (or
suffer any liquidation or dissolution), or convey, sell, lease, assign, transfer
or otherwise dispose of, all or substantially all of its property, business or
assets, except:

          (a) any Subsidiary of Immunex may take any of the foregoing actions;
          provided, that, after giving pro form effect to such action, Guarantor
          --------
          shall be in compliance with all covenants hereunder;

          (b) Guarantor may be merged or consolidated with or into any other
          Person, provided, that Guarantor shall be the continuing or surviving
                  --------
          corporation and after giving pro form effect to such merger or
          consolidation, Guarantor shall be in compliance with all covenants
          hereunder; and

          (c) pursuant to the Operative Agreements.

          10.4 Limitation on Sale or Lease of Assets. Convey, sell, lease,
          ------------------------------------------
assign, transfer or otherwise dispose of any of its property, business or assets
(including, without limitation, receivables and leasehold interests), whether
now owned or hereafter acquired, except:

          (a) obsolete or worn out property disposed of in the ordinary course
          of business;

          (b) the sale of inventory in the ordinary course of business;

          (c) the sale by Immunex or its Subsidiaries of those lines of business
          identified on Schedule 10.4(c);
                        ----------------

          (d) the sale or discount without recourse of defaulted accounts
          receivable arising in the ordinary course of business in connection
          with the compromise or collection thereof;

          (e) as permitted by Section 10.3;

          (f) the lease by a Subsidiary as lessor of real estate properties to
          Immunex or any Subsidiary of Immunex for use by Immunex or such
          Subsidiary as the site of its offices and facilities;

          (g) pursuant to the Operative Agreements; and

                                       13
<PAGE>

          (h) the conveyance, sale, lease, assignment, transfer or other
          disposal of property, business or assets of Immunex and its
          Subsidiaries which are not material to a principal business of
          Immunex, provided such sale could not reasonably be expected to have a
          Material Adverse Effect.

          10.5 Limitation on Dividends. Declare or pay any dividend (other than
          ----------------------------
dividends payable solely in common stock of such Person) on, or make any payment
on account of, or set apart assets for a sinking or other analogous fund for,
the purchase, redemption, defeasance, retirement or other acquisition of, any
shares of any class of Capital Stock of such Person or any warrants or options
to purchase any such Capital Stock, whether now or hereafter outstanding, or
make any other distribution in respect thereof, either directly or indirectly,
whether in cash or property or in obligations of Immunex or any Subsidiary of
Immunex, except that if no Default or Event of Default exists or would
reasonably be expected to be caused thereby (i) Subsidiaries of Guarantor may
declare and pay dividends to Guarantor and other shareholders of such
Subsidiaries, and (ii) during any fiscal year of Immunex following the Closing
Date, Immunex shall be permitted to declare cash dividends or repurchase its
Capital, provided that after giving pro forma effect to the any such
declarations, payments or repurchases, Guarantor shall be in compliance with all
other covenants hereunder.

          10.6 Nature of Business. Engage in any principal business other than
          -----------------------
business in the same general type of industry or industries in which its
business is now conducted, or in conjunction therewith, in any industry or
industries complementary thereto as reasonably determined by Immunex.

          10.7 Change in Control. Permit or otherwise allow either (i) a
          ----------------------
"person" or a "group" (within the meaning of Sections 13(d) and 14(d)(2) of the
Securities Exchange Act) other than American Home Products Corporation, a
Delaware corporation (or its affiliates or successors) to become the "beneficial
owner" (as defined in Rule 13d-3 under the Securities Exchange Act) of more than
50% of the then outstanding voting stock of Immunex, or (ii) a majority of the
Board of Directors of Immunex to consist of individuals who are not Continuing
Directors; "Continuing Director" means, as of any date of determination, (x) an
            -------------------
individual who on the date two (2) years prior to such determination date was a
member of Immunex's Board of Directors, or (y) any new director whose election
or nomination for election by Immunex's shareholders, was approved by a vote of
at least a majority of the directors then still in office who either were
directors on the date two (2) years prior to such determination date or whose
election, or nomination for election, was previously so approved.

          11. Notices. All notices, requests and demands to or upon Collateral
              -------
Agent, any Beneficiary or the Guarantor to be effective shall be in writing
(including by telecopy) by United States certified or registered mail (postage
prepaid), by nationally recognized courier service, by hand or by telecopy with
confirming notice and any such notice shall become effective upon receipt and
shall be directed to any Beneficiary or Guarantor, as the case may be, at each
of their respective addresses or transmission numbers for notices provided in
Section 14.3 of the Participation Agreement. Each Beneficiary and the Guarantor
may change its address and transmission numbers for notices by notice in the
manner provided in Section 14.3 of the Participation Agreement.

                                       14
<PAGE>

           12. Severability. Any provision of this Guarantee that is prohibited
               ------------
or unenforceable in any jurisdiction shall, as to such jurisdiction, be
ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining provisions hereof, and any such prohibition or
unenforceability in any jurisdiction shall not invalidate or render
unenforceable such provision in any other jurisdiction.

           13. Integration. This Guarantee and other applicable Operative
               -----------
Agreements represent the agreement of the Guarantor with respect to the subject
matter hereof and there are no promises or representations by Collateral Agent
or any Beneficiary relative to the subject matter hereof not reflected herein.

           14. Amendments in Writing; No Waiver; Cumulative Remedies. (a) None
               -----------------------------------------------------
of the terms or provisions of this Guarantee may be waived, amended,
supplemented or otherwise modified except as provided in Section 14.5 of the
Participation Agreement.

           (b) Neither Collateral Agent nor any Beneficiary shall, by any act
(except by a written instrument pursuant to Section 14(a) hereof), delay,
indulgence, omission or otherwise be deemed to have waived any right or remedy
hereunder or to have acquiesced in any Default or Event of Default or in any
breach of any of the terms and conditions hereof. No failure to exercise, nor
any delay in exercising, on the part of Collateral Agent or any Beneficiary, any
right, power or privilege hereunder shall operate as a waiver thereof. No single
or partial exercise of any right, power or privilege hereunder shall preclude
any other or further exercise thereof or the exercise of any other right, power
or privilege. A waiver by Collateral Agent or any Beneficiary of any right or
remedy hereunder on any one occasion shall not be construed as a bar to any
right or remedy that Collateral Agent or such Beneficiary would otherwise have
on any future occasion.

           (c) The rights and remedies herein provided are cumulative, may be
exercised singly or concurrently and are not exclusive of any other rights or
remedies provided by law.

           15. Section Headings. The section headings used in this Guarantee are
               ----------------
for convenience of reference only and are not to affect the construction hereof
or be taken into consideration in the interpretation hereof.

           16. Successors and Assigns. This Guarantee shall be binding upon the
               ----------------------
successors and assigns of the Guarantor and shall inure to the benefit of
Collateral Agent and the Beneficiaries and their successors and permitted
assigns.

           17. SUBMISSION TO JURISDICTION; WAIVERS. (a) THE GUARANTOR HEREBY
               -----------------------------------
IRREVOCABLY AND UNCONDITIONALLY:

               (i) SUBMITS FOR ITSELF AND ITS PROPERTY IN ALL LEGAL ACTIONS OR
           PROCEEDINGS RELATING TO THIS GUARANTEE OR ANY OTHER OPERATIVE
           AGREEMENT TO WHICH IT IS A PARTY, OR FOR RECOGNITION AND ENFORCEMENT
           OF ANY JUDGMENT IN RESPECT THEREOF TO THE NON-EXCLUSIVE GENERAL
           JURISDICTION OF THE COURTS OF THE STATE OF NEW YORK AND THE COURTS OF
           THE

                                       15
<PAGE>

           UNITED STATES LOCATED IN THE SOUTHERN DISTRICT OF NEW YORK, AND
           APPELLATE COURTS THEREOF;

               (ii)  CONSENTS THAT ANY SUCH ACTION OR PROCEEDING MAY BE BROUGHT
           IN SUCH COURT, WAIVES ANY OBJECTION THAT IT MAY HAVE NOW OR HEREAFTER
           TO THE VENUE OF ANY SUCH ACTION OR PROCEEDING IN ANY SUCH COURT AND
           WAIVES ANY OBJECTION THAT SUCH ACTION OR PROCEEDING IN ANY SUCH COURT
           WAS BROUGHT IN AN INCONVENIENT FORUM AND AGREES NOT TO PLEAD, CLAIM
           OR ASSERT THE SAME;

               (iii) AGREES THAT SERVICE OF PROCESS IN ANY SUCH ACTION OR
           PROCEEDING IN ANY SUCH COURT MAY BE EFFECTED BY MAILING A COPY
           THEREOF BY REGISTERED OR CERTIFIED MAIL (OR ANY SUBSTANTIALLY SIMILAR
           FORM OF MAIL), POSTAGE PREPAID TO, OR BY PERSONAL SERVICE AT, ITS
           ADDRESS SET FORTH HEREIN OR SUCH OTHER ADDRESS OF WHICH THE AGENT
           SHALL HAVE BEEN NOTIFIED PURSUANT HERETO, WHETHER OR NOT SUCH ADDRESS
           BE WITHIN THE JURISDICTION OF ANY SUCH COURT;

               (iv)  AGREES THAT NOTHING HEREIN SHALL AFFECT THE RIGHT TO EFFECT
           SERVICE OF PROCESS IN ANY OTHER MANNER PERMITTED BY LAW OR SHALL
           LIMIT THE RIGHT OF THE AGENT (AND NOT OF THIS GUARANTOR) TO SUE IN
           ANY OTHER JURISDICTION; AND

               (v)   WAIVES, TO THE MAXIMUM EXTENT NOT PROHIBITED BY LAW, ANY
           RIGHT IT MAY HAVE TO CLAIM OR RECOVER IN ANY LEGAL ACTION OR
           PROCEEDING REFERRED TO IN THIS SECTION 17 ANY SPECIAL, EXEMPLARY, OR
           PUNITIVE DAMAGES.

           (b) THE GUARANTOR HEREBY IRREVOCABLY AND UNCONDITIONALLY WAIVES TRIAL
BY JURY IN ANY LEGAL ACTION OR PROCEEDING RELATING TO THIS GUARANTEE OR ANY
OTHER OPERATIVE AGREEMENT AND FOR ANY COUNTERCLAIM THEREIN.

           18. GOVERNING LAW. THIS GUARANTEE SHALL BE GOVERNED BY, AND CONSTRUED
               -------------
AND INTERPRETED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

           19. Survival of Representations, Warranties, etc. All
               --------------------------------------------
representations, warranties, covenants and agreements made herein and in
statements or certificates delivered pursuant hereto shall survive any
investigation or inspection made by or on behalf of the Lessor and shall
continue in full force and effect until all of the obligations of the Guarantor
under this Guarantee shall be fully performed in accordance with the terms
hereof, and until the payment in full of all sums payable by the Lessee under
the Operative Agreements, and until performance in

                                       16
<PAGE>

full of all obligations of the Lessee in accordance with the terms and
provisions of such agreements.

          20.  Third Party Beneficiaries. The Guarantor expressly acknowledges
               -------------------------
and agrees that each Indemnified Person shall be a third party beneficiary of
this Guarantee.

          21.  Action by Administrative Agent. The Administrative Agent shall
               ------------------------------
only take action hereunder as directed by SPC.

                                       17
<PAGE>

          IN WITNESS WHEREOF, the undersigned has caused this Guarantee to be
duly executed and delivered by its duly authorized officer as of the day and
year first above written.

                                         IMMUNEX CORPORATION

                                         By:       /s/ David A. Mann
                                             -------------------------------
                                             Name: David A. Mann
                                             Title: Executive Vice President,
                                                      Chief Financial Officer
                                                      and Treasurer

                                         IMMUNEX MANUFACTURING CORPORATION

                                         By:       /s/ David A. Mann
                                             -------------------------------
                                             Name: David A. Mann
                                             Title: Treasurer

                                       18<PAGE>

                                                                    EXHIBIT 10.3

                                AGENCY AGREEMENT

     AGENCY AGREEMENT, dated as of March 2, 2001 (this "Agreement"), between
                                                        ---------
IMMUNEX REAL ESTATE TRUST 2001, a Delaware business trust (the "Lessor"), and
                                                                ------
IMMUNEX CORPORATION, a Washington corporation (the "Construction Agent").
                                                    ------------------

                              Preliminary Statement
                              ---------------------

     A.  The Lessor and Lessee are parties to the Lease, pursuant to which
Lessee has agreed to lease the Property from the Lessor.

     B.  The Lessor and Lessee are also parties to that certain Participation
Agreement, dated as of the date hereof (as amended or otherwise modified from
time to time, the "Participation Agreement"), among Immunex Corporation, Immunex
                   -----------------------
Funding Corp., as SPC, Wilmington Trust Company, not in its individual capacity
except as set forth therein, but solely as Trustee, the Lessor, the financial
institutions listed on Schedule II thereto as Investors, the financial
institutions listed on Schedule I thereto as Banks, The Chase Manhattan Bank, as
Administrative Agent, Collateral Agent and Agent Bank.

     C.  Subject to the terms and conditions hereof, (i) the Lessor desires to
appoint the Construction Agent as its sole and exclusive agent in connection
with the acquisition of the construction of the Improvements in accordance with
the Plans and Specifications and (ii) the Construction Agent desires, for the
benefit of the Lessor, to cause the construction of the Improvements in
accordance with the Plans and Specifications as hereinafter set forth.

     NOW, THEREFORE, in consideration of the foregoing, and for other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto covenant and agree as follows:

                             SECTION 1. DEFINITIONS

     1.1 Defined Terms. Capitalized terms used and not defined herein shall have
     -----------------
the meanings assigned thereto in Annex A to the Participation Agreement; and the
rules of interpretation set forth in Annex A to the Participation Agreement
shall apply to this Agreement.
<PAGE>

                  SECTION 2. APPOINTMENT OF CONSTRUCTION AGENT

     2.1 Appointment and Acceptance. Subject to the terms and conditions hereof
     ------------------------------
and of the Participation Agreement and Lease, the Lessor hereby irrevocably
designates and appoints the Construction Agent as its exclusive agent in
connection with construction of the Improvements in accordance with the Plans
and Specifications. The Construction Agent hereby accepts the designation and
appointment as construction agent and agrees to perform such functions and
duties as set forth herein.

     2.2 Term.  This Agreement shall commence on the date hereof and shall
     --------
terminate with respect to the Property upon the earlier to occur of:

          (i)   the Completion Date;

          (ii)  the termination of this Agreement pursuant to Section 5 hereof
     and the satisfaction by the Construction Agent of all obligations
     hereunder; and

          (iii) the exercise by the Construction Agent of the Purchase Option
     set forth in Section 20.1 of the Lease;

provided, however, that any termination of this Agreement shall not relieve the
--------  -------
Construction Agent for liability for breach hereof.

     2.3 Scope of Authority. (a) The Lessor hereby expressly authorizes the
     ----------------------
Construction Agent to, and the Construction Agent shall, take all action
necessary or desirable for the construction of the Improvements in accordance
with the Plans and Specifications and the Budget and to fulfill all of the
obligations of the Construction Agent, including, without limitation:

          (i)   the right to approve payment of all invoices for services and
     materials related to the development, design, construction and equipping of
     the Improvements, and to submit Requisitions under the SPC Loan Agreement
     and the Participation Agreement and to receive the proceeds of Advances
     under the SPC Loan Agreement and to receive the same directly from the
     Administrative Agent provided, however, the Construction Agent shall not
                          --------  -------
     incur any expenses in excess of an amount equal to the sum of the SPC Loan
     Commitments plus the Investors Contribution Commitment without the express
     written consent of the Lessor;

          (ii)  all design and supervisory functions relating to the
     construction of the Improvements and performing all engineering work
     related to the construction of the Improvements;

          (iii) negotiating and entering into all contracts or arrangements for
     the construction of the Improvements, development of infrastructure
     relating thereto, and the procurement of the equipment necessary to
     construct the Improvements on such terms and conditions as are customary
     and reasonable in light of local standards and practices;

                                      -2-
<PAGE>

          (iv)   obtaining all necessary permits, licenses, consents, approvals
     and other authorizations, including those required under applicable
     Environmental Laws, from all Governmental Authorities in connection with
     the development and construction of the Improvements substantially in
     accordance with the Plans and Specifications;

          (v)    maintaining all books and records with respect to the
     construction, operation and management of the Property;

          (vi)   contesting any mechanics' or materialmen's lien and
     prosecuting all other permitted contest rights of Lessee under Section 13.1
     of the Lease during the Construction Period;

          (vii)  performing those actions permitted to be performed by the
     Lessee under Section 12.2 of the Lease during the Construction Period;

          (viii) bringing or defending any claims or seeking resolution of any
     disputes arising from the Construction Agent's performance of the foregoing
     obligations;

          (ix)   performing any other acts necessary in connection with
     construction and development of the Improvements in accordance with the
     Plans and Specifications;

          (x)    submitting Requisitions to the Administrative Agent under the
     Participation Agreement and receiving the proceeds of Advances; and

          (xi)   maintaining the insurance required pursuant to Section 6
     hereof.

     (b)  Neither the Construction Agent nor any of its Affiliates or agents
shall, without the written consent of the Lessor, enter into any contract which
would, directly or indirectly, impose any liability or obligation on the Lessor,
any Bank or the Administrative Agent beyond the liability or obligations
permitted under the Operative Agreements, and each such contract shall be non-
recourse to Lessor, the Banks and the Administrative Agent in accordance with
Section 30.6 of the Lease.

     (c)  Subject to the terms and conditions of this Agreement, the
Construction Agent shall have sole management and control over the construction
means, methods, sequences and procedures with respect to the construction of the
Improvements.

     2.4  Delegation of Duties. The Construction Agent may execute any of its
     -------------------------
duties under this Agreement by or through agents, contractors, employees or
attorneys-in-fact and may enter into agreements with architects and contractors
for the purpose of so delegating such duties; provided that no such delegation
shall limit or reduce in any way the Construction Agent's duties and obligations
under this Agreement.

     2.5  Covenants of the Construction Agent. The Construction Agent hereby
     ----------------------------------------
covenants and agrees that it will:

                                      -3-
<PAGE>

     (a) cause construction of the Improvements to be prosecuted diligently and
continuously in accordance with the Plans and Specifications and in compliance
with all Legal Requirements and Insurance Requirements (except where the failure
to comply with Legal Requirements and Insurance Requirements is not material);

     (b) cause the Completion Date to occur on or prior to the Outside
Completion Date, free and clear (by removal or bonding) of Liens (other than
Permitted Liens or Lessor Liens) or material claims for materials supplied or
labor and services performed in connection with the construction of the
Improvements; provided, that the failure to cause the Completion Date to occur
              --------
by the Outside Completion Date shall not be deemed a breach hereunder if such
delay is caused by a Force Majeure Event and Completion is accomplished within
three (3) months of the date otherwise applicable but for this proviso;
provided, further, to the extent such failure to complete is caused by a Force
--------  -------
Majeure Event extending beyond such three (3) month period, the Construction
Agent shall elect one of the Construction Agent Options set forth in Section 2.6
and, if such election is not made within ten (10) Business Days of the end of
such three (3) month period, the Construction Agent shall be deemed to have
elected to purchase the Property for the Termination Value in accordance with
the provisions of Section 2.6;

     (c) notify the Lessor in writing not less than five (5) Business Days after
the Responsible Officer of the Construction Agent believes in his or her
reasonable judgment that the Completion of Construction will not occur on or
prior to the Outside Completion Date;

     (d) promptly notify the Lessor and the Administrative Agent in writing of
the occurrence of any Force Majeure Event and take all reasonable and practical
steps to minimize the disruption of the construction process arising from Force
Majeure Events;

     (e) comply in all respects with all Legal Requirements (including
Environmental Laws) and Insurance Requirements required for the Construction of
Improvements during the Construction Period;

     (f) procure, maintain and comply with all licenses, permits, orders,
approvals, consents, and other authorizations required for the construction of
the Improvements and provide information to the Lessor within a reasonable time
after the Lessor's request for such information regarding the status of the
foregoing;

     (g) subject to the limitations of Section 5.4(a) hereof and the receipt of
sufficient funds in accordance with Section 4.1 hereof, pay and discharge any
and all Project Costs, including, without limitation, the costs of, as
applicable, constructing, equipping and furnishing the Improvements and payment
of all real estate taxes, insurance premiums and other items payable prior to
Completion, as the same become due and payable;

     (h) following the Completion Date use reasonable good-faith efforts to
cause all outstanding punch list items with respect to the Improvements on the
Property to be completed, but in any event within three (3) months following the
Completion Date; and

     (i) comply fully and punctually with all of the material terms, covenants
and conditions on its part to be complied with under the agreements entered into
by Construction Agent pursuant to paragraph 2.3 (a) (iii) hereof.

                                      -4-
<PAGE>

     2.6 Options. (a) After the Construction Agent gains knowledge or a
     -----------
reasonable expectation that the costs for construction of the Improvements shall
exceed the original Budget (or exceed the Budget as modified in accordance with
the Operative Agreements) or that Completion shall not occur on or prior to the
Outside Completion Date, the Construction Agent shall promptly (and in any event
within five (5) Business Days of gaining such knowledge or expectation) notify
the Administrative Agent in writing of the same. If at any time prior to the
Outside Completion Date, the Lessor shall have (x) determined in its reasonable
good faith judgment that (i) the sum of the available SPC Loan Commitment and
the available Investor Contribution Commitment shall be less than the amounts
necessary for Completion of the Improvements or (ii) Completion of the
Improvements shall not occur on or prior to the Outside Completion Date, or (y)
received any notice from the Construction Agent as referenced in the preceding
provisions of this paragraph, then in any such case Lessor shall have the option
to cease advancing Project Costs and/or replace the Construction Agent with a
new construction agent selected by the Lessor to finalize the Completion of the
Improvements. The cost and expense incurred to finalize the Completion of the
Improvements as referenced in the preceding sentence shall be the responsibility
of the Construction Agent and shall be payable by the Construction Agent on
demand; provided, in no event shall the obligations of the Construction Agent
for such costs and expenses exceed the amounts payable by the Construction Agent
under Section 5.4(a); provided, further, amounts expended by the Lessor to
finalize the Completion of the Improvements as referenced in the preceding
sentence shall be added to the Project Cost.

     (b) The costs of Completion of the Improvements in excess of the original
Budget (or the Budget as modified in accordance with the Operative Agreements)
in each case as previously delivered to the Lessor shall not be the
responsibility of the Construction Agent but instead shall be paid by Lessor, if
the Lessor so elects, from Advances made by SPC and the Investors to the extent,
but only to the extent, that (after taking into account such excess costs and
any other items of excess cost which are then known to the Construction Agent or
are reasonable for the Construction Agent to expect) the conditions precedent
set forth in Section 6.3 of the Participation Agreement are satisfied.

     (c) Subject to SPC and the Investors not agreeing to continue making
advances in accordance with the provisions of the next paragraph and in the
event from time to time (i) the Construction Agent gains knowledge or a
reasonable expectation that the costs of the Improvements shall exceed the
original Budget (or exceed the Budget as modified in accordance with the
Operative Agreements) or that Completion of the Improvements shall not occur on
or prior to the Outside Completion Date, or (ii) the Lessor shall have
determined in its reasonable good faith judgment that the sum of the available
SPC Loan Commitment and the available Investor Contribution Commitment shall be
less than the amounts necessary for Completion of the Improvements or that
Completion of the Improvements shall not occur on or prior to the Outside
Completion Date, the Construction Agent shall elect and comply (within ten (10)
days of the Construction Agent gaining such knowledge or expectation or within
ten (10) days of the Lessor making such determination and giving written notice
of the same to the Construction Agent, as referenced in subsections (i) and (ii)
above of this paragraph) with one of the options set forth in the following
subsections (A) or (B) (collectively, the "Construction Agent Options"): (A) the
                                           --------------------------
Construction Agent shall pay to the Lessor, on a date designated by the Lessor,
an aggregate amount equal to (x) the Termination Value, plus (y) any and all
fees and expenses incurred by or on behalf of the Lessor in connection with the
Property (including without limitation the transfer thereof) and on such date
the Lessor shall transfer and convey to the Construction Agent all right, title
and interest of the Lessor in and to the Property, or (B) the

                                      -5-
<PAGE>

Construction Agent shall pay to the Lessor, on a date designated by the Lessor,
any and all amounts that are due hereunder or under any other Operative
Agreement upon the occurrence of an Agency Agreement Event of Default, subject
to the limitation provided for in Section 5.4(a), and on and after such date,
the Construction Agent and the Lessee shall be irrevocably deemed, without any
further action, to have relinquished, and shall relinquish in accordance with
Section 10.2 of the Lease, all of its right, title and interest in and to all,
but not less than all, the Property and to have transferred and conveyed all
such right, title and interest to the Lessor, and the Construction Agent shall
execute and deliver to the Lessor or its designee, at the cost and expense of
the Construction Agent, each of the following: (w) special or limited warranty
Deeds and other appropriate assignments conveying the Property to the Lessor or
its designees free and clear of the Lien of the Lease, and the Lien of the
Credit Documents; (x) a Bill of Sale conveying the Property (to the extent they
consist of personal property) to the Lessor or its designee free and clear of
the Lien of the Lease, and the Lien of the Credit Documents; and (y) any real
estate tax affidavit or other document required by law to be executed and filed
in order to record the applicable deed or other assignments. In connection with
any transfer of the Improvements as referenced above in this Section 2.6(c) by
the Lessor to the Construction Agent, the Lessor shall execute and deliver to
the Construction Agent, at the cost and expense of the Construction Agent
(subject to the limitations described in the next sentence), each of the
following: (w) special or limited warranty deeds and other appropriate
assignments conveying the Property to the Construction Agent free and clear of
the Lien of the Lease, the Lien of the Credit Documents and any Lessor Liens;
(x) a bill of sale conveying the Property (to the extent they consist of
personal property) to the Construction Agent free and clear of the Lien of the
Lease, the Lien of the Credit Documents and any Lessor Liens; and (y) any real
estate tax affidavit or other document required by law to be executed and filed
in order to record the applicable deed or other assignments. The Lessor shall
elect whether the out-of-pocket fees and expenses associated with the transfer
of the Property shall be paid by either (i) sales proceeds from the Property,
(ii) the Lessor (but only to the extent amounts are available therefor with
respect to the available SPC Loan Commitment and the available Investor
Contribution Commitment or SPC and each Investor approves the necessary
increases in the available SPC Loan Commitment and the available Investor
Contribution Commitment to fund such fees and expenses), or (iii) the
Construction Agent; provided, if the Construction Agent funds such fees and
expenses (as referenced in subsection (iii)) then the amounts payable under
clause (B) of the Construction Agent Options will be reduced accordingly.
Amounts funded by SPC and the Investors with respect to the foregoing shall be
added to the Project Costs. All of the foregoing documentation must be in form
and substance reasonably satisfactory to the Lessor. Subject to the foregoing,
the Property shall be conveyed to the Construction Agent "AS-IS", "WHERE-IS" and
in its then present physical condition.

     (d) In the event the costs in excess of any original Budget previously
delivered to the Administrative Agent for the Improvements are not funded by SPC
and the Investors because (after taking into account such excess costs and any
other items of excess cost which are then known to the Construction Agent or are
reasonable for the Construction Agent to expect) the conditions precedent set
forth in Section 6.3 of the Participation Agreement are not satisfied, then if,
but only if, the Banks and all the Investors agree at such time, (a) such excess
costs shall be funded and (b) the SPC Loan Commitment and the Investor
Contribution Commitment shall be increased accordingly.

                                      -6-
<PAGE>

                          SECTION 3. THE IMPROVEMENTS

     3.1 Amendments; Modifications. (a) The Construction Agent may at any time
         -------------------------
revise, amend or modify (i) the Plans and Specifications without the consent of
the Lessor; provided that any such revision, amendment or modification to the
Plans and Specifications does not (x) result in the Completion Date occurring
after the Outside Completion Date and/or (y) result in the Project Costs subject
to such amendment exceeding the sum of the then SPC Loan Commitments and the
then Investor Contribution Commitments, and (ii) the Budget; provided that such
revisions, amendments or modifications to the Budget do not result in any
increase in the Project Costs greater than the sum of the then SPC Loan
Commitments and the then Investor Contribution Commitments.

     (b) The Construction Agent agrees that it will not implement any revision,
amendment or modification to the Plans and Specifications if the aggregate
effect of such revision, amendment or modification would be to reduce the Fair
Market Sales Value of the Property as set forth in the Appraisal of the
Property, below the sum of the then outstanding SPC Loan and Investor
Contribution when completed, unless such revision, amendment or modification is
required by Legal Requirements or Insurance Requirements.

                          SECTION 4. PAYMENT OF FUNDS

     4.1 Right to Receive Construction Cost. (a) During the course of the
         ----------------------------------
construction of the Improvements, the Construction Agent may request that the
Lessor advance funds for the payment of Project Costs, and the Lessor will
comply with such request to the extent provided for under the Participation
Agreement. The Construction Agent and the Lessor acknowledge and agree that the
Lessee's right to request funds and the Lessor's obligation to advance funds for
the payment of Project Costs is subject in all respects to the terms and
conditions of the Participation Agreement and each of the other Operative
Agreements.

     (b) The proceeds of any funds made available to the Lessor to pay Project
Costs shall be made available to the Construction Agent or its designee in
accordance with the Requisition relating thereto and the terms of the
Participation Agreement. The Construction Agent will use such proceeds only to
pay the Project Costs set forth in the Requisition relating to such funds.

     (c) Notwithstanding anything herein to the contrary, the Lessor shall not
be required to make advances to pay or reimburse or compensate the Construction
Agent with respect to or arising out of a Construction Period Force Majeure
Event, including a Construction Period Force Majeure Event Loss.

                          SECTION 5. EVENTS OF DEFAULT

     5.1 Events of Default. If any one or more of the following events (each, as
     ---------------------
used in this Agreement, an "Agency Agreement Event of Default") shall occur:
                            ---------------------------------

                                      -7-
<PAGE>

     (a) the Construction Agent fails to apply any funds paid by the Lessor to
the Construction Agent for the construction of the Improvements to the payment
of Project Costs; or

     (b) the Construction Commencement Date with respect to the Improvements
does not occur within three (3) months of the Closing Date; provided, that the
                                                            --------
failure to commence construction within such three (3) month period shall not be
deemed a breach hereunder if such delay is caused by a Force Majeure Event and
the Construction Commencement Date occurs within three (3) months of the date
otherwise applicable but for this proviso; provided, further, to the extent such
                                           --------  -------
failure to commence construction of the Improvements is caused by a Force
Majeure Event extending beyond such three (3) month period, the Construction
Agent shall elect one of the Construction Agent Options set forth in Section 2.6
and, if such election is not made within ten (10) Business Days of the end of
such three (3) month period, the Construction Agent shall be deemed to have
elected to purchase all the Properties for the Termination Value in accordance
with the provisions of Section 2.6; or

     (c) the Construction Agent shall fail to observe its covenants set forth in
Section 6 hereof; or;

     (d) the Construction Agent shall fail to observe its covenants set forth in
Section 2.5(b) hereof and such failure shall have continued for thirty (30) days
after the date on which written notice thereof has been given to the
Construction Agent by the Lessor; provided, however, that so long as the
Construction Agent is making diligent efforts to cure such breach, the
Construction Agent shall not be in default during such longer period as is
reasonable for a curable breach which the Construction Agent is continuing in
its diligent efforts to cure, provided that in no event shall such breach
continue for a period in excess of an additional ninety (90) days; or

     (e) the Construction Agent shall fail to observe or perform any covenant
(other than any covenant described in clause (a), (b), (c) or (d) above) made by
it herein and such failure shall have continued for thirty (30) days after the
date on which written notice thereof has been given to the Construction Agent by
the Lessor; provided, however, that so long as the Construction Agent is making
diligent efforts to cure such breach, the Construction Agent shall not be in
default during such longer period as is reasonable for a curable breach which
the Construction Agent is continuing in its diligent efforts to cure, provided
that in no event shall such breach continue for a period in excess of an
additional ninety (90) days; or

     (f) the Construction Agent shall (i) admit in writing its inability to pay
its debts generally as they become due, (ii) file a petition under the United
States bankruptcy laws or any other applicable insolvency law or statute of the
United States of America or any State or Commonwealth thereof, (iii) make a
general assignment for the benefit of its creditors, (iv) consent to the
appointment of a receiver of itself or the whole or any substantial part of its
property, (v) fail to cause the discharge of any custodian, trustee or receiver
appointed for it or the whole or a substantial part of its property within sixty
(60) days after such appointment, or (vi) file a petition or answer seeking or
consenting to reorganization under the United States bankruptcy laws or any
other applicable insolvency law or statute of the United States of America or
any State or Commonwealth thereof; or

     (g) insolvency proceedings or a petition under the United States bankruptcy
laws or any other applicable insolvency law or statute of the United States of
America or any

                                      -8-
<PAGE>

State or Commonwealth thereof, (iii) make a general assignment for the benefit
State or Commonwealth thereof shall be filed against the Construction Agent and
not dismissed within sixty (60) days from the date of its filing (provided, that
the Construction Agent hereby expressly authorizes the Lessor to appear in any
court conducting any such proceeding during such sixty (60) day period to
preserve, protect and defend their respective rights under the Operative
Agreements), or a court of competent jurisdiction shall enter an order or decree
appointing, without the consent of the Construction Agent, a receiver of the
Construction Agent or the whole or a substantial part of any of their respective
property, and such order or decree shall not be vacated or set aside within
sixty (60) days from the date of the entry thereof; or

     (h) any representation or warranty made or deemed made by the Construction
Agent herein or in the Participation Agreement or which is contained in any
certificate or Requisition furnished at any time in connection with the
construction of the Improvements shall prove to have been incorrect, false or
misleading in any material respect on or as of the date made or deemed made;

     then, in any such event, and subject to Section 5.3(b), the Lessor may, in
addition to the other rights and remedies provided for in this Article,
terminate this Agreement by giving the Construction Agent five (5) days notice
of such termination and upon the expiration of the time fixed in such notice,
this Agreement shall terminate and all rights and obligations of the
Construction Agent and the Lessor under this Agreement shall cease. Subject to
the limitations of Section 5.4, the Construction Agent shall pay all costs and
expenses incurred by or on behalf of the Lessor, including reasonable fees and
expenses of counsel, and, upon demand, Termination Value, as a result of any
Agency Agreement Event of Default.

     5.2 Damages. The termination of this Agreement pursuant to Section 5.1
     -----------
shall in no event relieve the Construction Agent of its liability and
obligations hereunder, all of which shall survive any such termination.

     5.3 Remedies; Remedies Cumulative.
     ---------------------------------

     (a) Termination of Commitments, Acceleration, etc. Upon the occurrence and
         ---------------------------------------------
continuance of any Agency Agreement Event of Default of the type described in
Section 5.1(f) or Section 5.1(g), the Investor Contribution Commitments and the
SPC Loan Commitments shall automatically terminate and the Construction Agent
shall immediately become obligated to pay the then outstanding amount of the
Termination Value, without presentment, demand, protest, notice of acceleration
or other notice of any kind, all of which are hereby expressly waived, anything
in this Agreement or any other Operative Document to the contrary
notwithstanding. After the occurrence and continuance of any other Agency
Agreement Event of Default, the Lessor may by written notice to the Construction
Agent, immediately (x) terminate all Commitments, (y) terminate this Agreement
(and upon the giving of such notice, this Agreement shall terminate and all
rights of the Construction Agent and all obligations of the Lessor under this
Agreement (as the case may be) shall cease) and/or (z) subject to the
limitations imposed under Section 5.4, accelerate the amounts due and owing by
the Construction Agent hereunder and, upon any such notice of acceleration, the
Construction Agent shall, subject to the limitations imposed under Section 5.4,
immediately become obligated to pay all such amounts.

     (b) If (x) a Fully Indemnifiable Event shall have occurred, (y) an Event of
Default shall have occurred and be continuing and the occurrence of which is
Within the Construction Agent's Control (whether or not constituting, or arising
out of, a Fully

                                      -9-
<PAGE>

Indemnifiable Event), or (z) any Agency Agreement Event of Default described in
Section 5.1(b) or 5.1(d) shall have occurred and be continuing and the
occurrence of which is Within the Construction Agent's Control (whether or not
constituting, or arising out of, a Fully Indemnifiable Event) and the
Construction Agent and/or the Lessee shall have failed to relinquish all of its
interest in the Property, convey possession thereof to the Lessor or its
designee in compliance with Section 5.4(a) and/or shall have failed to comply
with the indemnification obligations under Section 12 of the Participation
Agreement, then, in each such case set forth in clauses (x), (y) and (z) above,
the Lessor shall have all rights and remedies available under the Operative
Agreements (including under Section 17.3 of the Lease) or available at law,
equity or otherwise, including the right to declare the Termination Value due
and owing.

     (c) No failure to exercise and no delay in exercising, on the part of the
Lessor, any right, remedy, power or privilege under this Agreement or under any
other Operative Agreement shall operate as a waiver thereof nor shall any single
or partial exercise of any right, remedy, power or privilege under this
Agreement preclude any other or further exercise thereof or the exercise of any
other right, remedy, power or privilege. The rights, remedies, powers and
privileges provided in this Agreement are cumulative and not exclusive of any
rights, remedies, powers and privileges provided by law.

     5.4 Limitation on Construction Agent's Recourse Liability. (a)
     ---------------------------------------------------------
Notwithstanding anything contained herein or in any other Operative Agreement to
the contrary, if (i) an Agency Agreement Event of Default described in Section
5.1(b) or 5.1(d) the occurrence of which is not Within the Construction Agent's
Control and does not constitute, and is not the result of, a Fully Indemnifiable
Event (a "Construction Risk Event") and (ii) no other Event of Default has
          -----------------------
occurred and is continuing (x) the occurrence of which is Within the
Construction Agent's Control, or (y)which does not constitute, and is not the
result of, a Fully Indemnifiable Event, then so long as the Construction Agent
relinquishes all of its interest in the Property and conveys possession thereof
to the Lessor or its designee in compliance with all Environmental Laws and the
requirements of Section 10.1 and 10.2 of the Lease (other than any such
requirement which requires completion of the Improvements), accompanied by an
affidavit to the Lessor to such effect and appropriate statements of
termination, the aggregate maximum recourse liability of the Construction Agent
with respect to such default to the Lessor or any Person claiming by, through or
under the Lessor under the Operative Agreements, shall be limited to the
Non-Completion Amount. The Construction Agent nonetheless acknowledges and
agrees that, subject to the provisions of Section 13.8(b) of the Participation
Agreement, (i) the Lessor shall be entitled to recover from the Property
(including through any reletting and/or sale of the Property or any portion
thereof) the entire outstanding funded amount of the SPC Loans and Investor
Contributions at the time of such Agency Agreement Event of Default, along with
all accrued and unpaid interest on the outstanding amount of the SPC Loans,
yield on the outstanding Investor Contributions and other amounts then due and
owing to the Lessor under the Operative Agreements and all other costs and
expenses of the Lessor incurred in connection with the Property (including
without limitation, any costs incurred in connection with the construction of
the Improvements and/or any reletting or sale of such Property or any portion
thereof) from and after the date of such return, and (ii) the foregoing recourse
limitations are exclusive of any amounts due and owing under Section 12 of the
Participation Agreement.

                                      -10-
<PAGE>

     (b) The proceeds received from any sale of the Property after the
Construction Agent has relinquished its interest in the Property pursuant to
Section 5.4(a) above shall be applied in accordance with Section 13.8 of the
Participation Agreement.

     5.5 Construction Agent's Right to Purchase. In the event that an Agency
     ------------------------------------------
Agreement Event of Default (other than an Agency Agreement Event of Default
under Section 5.1(f) or Section 5.1(g)), shall have occurred and be continuing,
the Construction Agent shall have the irrevocable option to purchase the
Property for a price equal to the Termination Value as of the date of such
purchase plus all other amounts due and owing hereunder, under the Participation
Agreement and the other Operative Agreements, such purchase to be effected in
accordance with the procedures set forth in Section 20 of the Lease; provided
that the Construction Agent shall have given written notice whether or not it
intends to do so within five (5) Business Days after the occurrence of such
Agency Agreement Event of Default and provided, further, that the Construction
Agent shall purchase the Property and pay all amounts due in connection
therewith within twenty (20) days after the occurrence of such Agency Agreement
Event of Default. If Lessor does not receive such a purchase notice within such
five (5) day period, then the Construction Agent shall be deemed to have
irrevocably elected to purchase the Property. The Construction Agent's purchase
of the Property in accordance with this Section 5.5 shall be deemed to cure the
applicable Agency Agreement Event of Default.

                     SECTION 6. INSURANCE AND CONDEMNATION

     6.1 Insurance. The Construction Agent shall procure and maintain in full
     -------------
force and effect or arrange to be procured and maintained in full force and
effect insurance for the Improvements during the Construction Period in
accordance with the following provisions:

     (a) Public Liability and Workers' Compensation Insurance. During the
         ----------------------------------------------------
Construction Period, the Construction Agent shall procure and carry or cause to
be procured and carried, at the Construction Agent's sole cost and expense,
commercial general liability insurance for the Construction Period risks arising
from the acts, errors or omissions of the Construction Agent while located on,
in possession of, or controlling or acting or failing to act with respect to the
Land and Construction. In addition, during the Construction Period, the
Construction Agent shall, in the construction of the Improvements on the Land
and the operation of the Land, comply with all applicable workers' compensation
laws. The Construction Agent acknowledges and agrees in this connection that the
Property is in its control and possession during the Construction Period
therefor, it is responsible as Construction Agent for the acts, errors or
omissions of its contractors, subcontractors and agents and that it has assumed
all liability arising from injury, damage or mishap to third Persons caused by
the Construction Agent or any person or entity under its control.

     (b) Hazard and Other Insurance. During the Construction Period, the
         --------------------------
Construction Agent shall arrange, on behalf of the Lessor, to obtain from an
insurance provider reasonably acceptable to the Lessor, and utilizing funds
advanced by the Lessor and keep in force a policy or policies of Builder's Risk
"All Risk" insurance with respect to the Land and Improvements insuring the
Lessor's interest in the Land and Improvements including collapse coverage and
fire insurance with extended coverage, written on a Standard Builder's Risk
Completed Value Form (100% non-reporting), in an amount equal to 100% of the
completed insurable replacement cost value of the Property. In addition, the
Construction Agent shall

                                      -11-
<PAGE>

arrange, on behalf of the Lessor and utilizing funds provided by the Lessor, for
the Lessor to obtain insurance from damage caused by collapse, flood or
earthquake covering losses up to $750 million. All such policies shall be in
form and substance reasonably satisfactory to the Lessor. The Lessor shall be
the named the mortgagee and loss payee under such policies. The premiums for
such coverage shall be paid with the proceeds of an advance of funds made by
Lessor for the Project Costs. In addition, the reduction in any recovery
pursuant to any deductible applicable to such policy shall be deemed a Project
Cost paid with the proceeds of an advance made by Lessor therefor; and,
provided, however that, unless the Lessor otherwise agrees, the deductible under
the all risk insurance policy required pursuant to this clause (b) shall not
exceed $100,000 per incident, loss or occurrence.

     (c) Deductibles. The insurance required to be obtained by the Construction
         -----------
Agent under Section 6.1(a) may be subject to such deductible amounts as is
consistent with the Construction Agent's or its Affiliates practice for other
properties similar to the Property owned or leased by the Construction Agent or
the Affiliates of the Construction Agent, and may be carried under blanket
policies maintained by or on behalf of the Construction Agent so long as such
policies otherwise comply with the provisions of this Section 6.1. The all risk
insurance required to be obtained by the Lessee pursuant to Section 6.1(b) shall
contain no deductible amount in excess of $100,000 per incident, loss or
occurrence unless the Lessor otherwise agrees.

     (d) Construction Manager. Should the Construction Agent decide to utilize
         --------------------
the services of a "Construction Manager or General Contractor", hereinafter
called the Construction Manager, on the Project, then said Construction Manager
shall procure and maintain, at its own expense, the following required insurance
of the kinds and limits as stipulated hereunder:

     (1) Worker's Compensation and Employer's Liability Insurance in accordance
with the applicable laws of the State in which the work is to be performed or of
the State in which the Construction Manager is obligated to pay compensation to
employees engaged in the performance of the work associated with this Project.
The policy limit under the Employer's Liability Insurance section shall not be
less than $1,000,000 (One Million Dollars) for any one accident. (2) Commercial
General Liability Insurance covering the work, the performance of the work and
everything incidental thereto, with limits of not less than $100,000,000 (One
Hundred Million Dollars) per occurrence combined single limit, or in whatever
higher amounts as may be required, and extended to cover: (a) Contractual
Liability Insurance assumed by the Construction Manager under any
Indemnification Agreement related to this Project, (b) if any of the work is
subcontracted, Independent Contractors Liability Insurance providing coverage in
connection with such portion of the work which may be subcontracted, (c) Broad
Form Property Damage Liability Insurance, and (d) Personal Injury Liability
Insurance. (3) Automobile Liability Insurance including coverage on owned, hired
and non-owned automobiles and other vehicles, if used in connection with the
performance of the work, with Bodily Injury and Property Damage limits of not
less the $50,000,000 (Fifty Million Dollars) per occurrence combined single
limit.

                                      -12-
<PAGE>

     (e)  Coverage. All insurance required to be carried or arranged for by the
          --------
Construction Agent or Construction Manager, accordingly, pursuant to the
requirements of Section 6.1(a), 6.1(b) or 6.1(d) shall provide in the policy or
by special endorsement that:

          (i)   in the case of insurance required by Section 6.1(a), that the
     Participants (except for the Banks) are included as additional insureds;

          (ii)  the insurer thereunder waives all rights of subrogation against
     the Lessor, and waives any right of set-off and counterclaim and any other
     right to deduction whether by attachment or otherwise;

          (iii) in case of insurance required by Section 6.1(d) such insurance
     shall be primary and shall apply to any loss or claim before any
     contribution of any other insurance carried by or on behalf of the Lessor
     or the Construction Agent;

          (iv)  the respective interests of the Lessor or the Construction
     Agent, as the case may be, under all insurance policies required hereunder
     shall not be invalidated by any action or inaction of the Lessee or the
     Construction Agent or any other Person (other than, with respect to any
     such insured, such insured) and such insurance shall insure the Lessor's
     interests, regardless of any breach or violation of any warranty,
     declaration or condition contained in such policies by the Lessee, the
     Construction Agent or any other Person (other than, with respect to any
     such insured, such insured);

          (v)   if the insurers cancel such insurance for any reason whatsoever
     or any materially adverse change is made in policy terms or conditions, or
     if such insurance is allowed to lapse for nonpayment of premium, such
     cancellation, change or lapse shall not be effective as to the Lessor for
     thirty (30) days after receipt by the Lessor of written notice from such
     insurers of such cancellation, change or lapse; and

          (vi)  with respect to all liability insurance, in as much as the
     policies are written to cover more than one insured, all terms, conditions,
     insuring agreements and endorsements, with the exception of the limits of
     liability, shall operate in the same manner as if there were a separate
     policy covering each insured.

     (f)  Adjustment of Losses. Losses, if any, with respect to the Property
under any damage policies required to be carried under Section 6.1(b) shall be
adjusted with the insurance companies, including the filing of appropriate
proceedings, as follows: (x) so long as no Agency Agreement Default shall have
occurred and be continuing, and provided that the Construction Agent is
required, or has agreed, to repair the damage, such losses shall be adjusted by
the Construction Agent, and (y) if any Agency Agreement Default shall have
occurred and be continuing, or if the Construction Agent is not required to, and
has not agreed, to repair the damage, such losses shall be adjusted by the
Lessor. The party which shall be entitled to adjust losses may appear in any
proceeding or action to negotiate, prosecute, adjust or appeal any claim for any
award, compensation or insurance payment on account of any Casualty and shall
pay all expenses thereof. At such party's reasonable request, and at the
Construction Agent's sole cost and expense with respect to disputes on insurance
required under Section 6.1(a), the

                                      -13-
<PAGE>

Construction Agent, and the Lessor, as the case may be, shall participate in any
such proceeding, action, negotiation, prosecution or adjustment. The parties
hereto agree that this Agreement shall control the rights of the parties hereto
in and to any such award, compensation or insurance payment relating to any
Casualty affecting the Property during the Construction Period.

     (g)  Application of Insurance Proceeds. All proceeds of insurance
          ---------------------------------
maintained pursuant to Section 6.1(b) on account of any damage to or destruction
of the Property during the Construction Period or any part thereof shall be paid
over to the Lessor or as it may direct; provided that if no Agency Agreement
Default shall have occurred such funds shall be held by the Lessor in a
segregated account and, so long as the Construction Agent is diligently
repairing the damage to the Property caused by the applicable Casualty,
disbursed to the Construction Agent to effect the repair of the Property.

     (h)  Title Insurance. Construction Agent shall cause the Title Company to
          ---------------
issue the title insurance referred to in Section 6.3(d) of the Participation
Agreement.

     (i)  Additional Insurance. Any additional insurance obtained by the
          --------------------
Construction Agent or the Lessor shall provide that it shall not limit the
insurance described in Sections 6.1(a) and 6.1(b) or increase the amount of any
premium payable with respect to any such insurance. The proceeds of any
additional insurance will be for the account of the party maintaining such
additional insurance.

     (j)  Insurance Report. On the commencement of construction of the
          ----------------
Improvements and annually thereafter, the Construction Agent shall provide the
Lessor, promptly following Lessor's written request therefor, an insurance
certificate certifying compliance with the insurance then required to be
maintained by the Construction Agent pursuant to this Section 6.1, provided
however, the Construction Agent shall provide the Lessor with written notice
thirty (30) days prior to the expiration of any insurance policy required to be
maintained pursuant to the terms of this Agreement.

     6.2  Condemnation.
     -----------------

     (a)  Representation and Warranties of the Construction Agent with respect
          --------------------------------------------------------------------
to Condemnation. The Construction Agent hereby represents and warrants to the
---------------
Lessor (which representation and warranty shall be deemed to be repeated and be
considered part of each Requisition) that to the actual knowledge of the
Construction Agent there is no action being taken by any Person with respect to
any actual, pending or threatened Condemnation affecting the Property.

     (b)  Condemnation Occurrences.
          ------------------------

               (i)    Condemnation Proceedings. The Construction Agent hereby
                      ------------------------
     agrees that it shall, within five (5) Business Days after the date on which
     the Construction Agent shall have notice thereof, give notice to the Lessor
     of each action or proceeding by any Governmental Authority with respect to
     any actual, pending or threatened Condemnation during the Construction
     Period and whether or not as a result thereof Completion of the
     Improvements will be completed on or before the Outside Completion Date and
     is exercising a Construction Agent Option pursuant to Section 2.6(c).
     During the Construction Period, the Lessor shall be entitled, to the
     exclusion of the Construction Agent, to negotiate,

                                      -14-
<PAGE>

     prosecute, adjust or appeal any claim for any award, compensation or
     insurance payment on account of any Condemnation having a material effect
     on the Property. The Lessor shall consult with the Construction Agent in
     connection with the foregoing, but the Construction Agent shall have no
     right to participate in any such negotiation, prosecution, adjustment or
     appeal unless the Lessor consents thereto in its sole discretion. During
     the Construction Period, the Construction Agent shall be entitled, with the
     approval of the Lessor, which shall not be unreasonably withheld,
     conditioned or delayed, to negotiate, prosecute, adjust or appeal any claim
     for any award, compensation or insurance payment on account of any
     Condemnation which does not have a material effect on the Property.

               (ii)    Condemnation Awards. During the Construction Period, all
                       -------------------
     awards, compensation and insurance payments on account of any Condemnation
     affecting the Property shall be paid directly to the Lessor or, if received
     by the Construction Agent, shall be held in trust for the Lessor and shall
     promptly be paid over by the Construction Agent to the Lessor. In the event
     the Construction Agent elects to proceed under clause (A) of the definition
     of "Construction Agent Options" in Section 2.6(c), all such amounts paid to
     Lessor shall be paid to the Construction Agent upon Lessor receiving all
     amounts due under such clause (A), and if no Construction Agent Option
     shall have been exercised, and the Property suffering a Condemnation is in
     the reasonable judgment of the Lessor capable of being restored to a
     condition, functionally and economically, equivalent to that which existed
     prior to such Condemnation for a restoration cost equal to or less than the
     award or compensation received by the Lessor with respect to the
     Condemnation, then, so long as no Agency Agreement Default has occurred and
     is continuing and such restoration can be completed on or prior to the
     Outside Completion Date, then such award or compensation shall be made
     available to the Construction Agent to finance such restoration and the
     Construction Agent shall effect such restoration on or prior to the Outside
     Completion Date. To the extent the Lessor elects to retain such award or
     compensation and apply it to the Termination Value and such award or
     compensation exceeds the Termination Value, such amount shall be applied in
     accordance with Section 13.5(b) and 13.5(c) of the Participation Agreement.

            SECTION 7. LESSOR'S RIGHTS; CONSTRUCTION AGENT'S RIGHTS

     7.1 Exercise of the Lessor's Rights. Subject to the terms of the Contract
     -----------------------------------
Assignment made by the Lessor in favor of the Administrative Agent, the
Construction Agent hereby acknowledges and agrees that the rights and powers of
the Lessor under this Agreement have been assigned to the Administrative Agent.

     7.2 Lessor's Right to Cure Construction Agent's Defaults. Upon written
     --------------------------------------------------------
notice to the Construction Agent, except in emergencies, the Lessor, without
waiving or releasing any obligation or Agency Agreement Event of Default, may
(but shall be under no obligation to) remedy any Agency Agreement Event of
Default hereunder for the account of and at the sole cost and expense of the
Construction Agent, subject to the limitations on Construction Agent's liability
to

                                      -15-
<PAGE>

Lessor set forth herein. All reasonable out of pocket costs and expenses so
incurred (including reasonable fees and expenses of counsel), together with
interest thereon at the Overdue Rate from the date on which such sums or
expenses are paid by the Lessor, shall be paid by the Construction Agent to the
Lessor on demand.

          7.3 Subordination. (a) All liabilities and obligations of the Lessor
          -----------------
     to the Construction Agent, whether secured or unsecured and whether or not
     evidenced by any instrument, now existing or subsequently created or
     incurred, are and shall be subordinate and junior in right of payment to
     the Secured Obligations.

          (b) The Construction Agent shall not sell, assign or otherwise
     transfer, in whole or in part, or create, incur or suffer to exist any
     security interest, Lien, charge or other encumbrance with respect to any
     indebtedness, liabilities or obligations of the Lessor to the Construction
     Agent or any instrument or document evidencing or securing the same unless,
     in any such case, the person or entity to whom such sale, assignment or
     transfer is made or the beneficiary of such security interest, Lien, charge
     or encumbrance acknowledges the foregoing subordination and agrees to be
     bound thereby. Notwithstanding the foregoing, the Lessor acknowledges
     Lessee's right to finance and to secure under the Uniform Commercial Code,
     inventory, furnishings, furniture, equipment, machinery, leasehold
     improvements and other personal property located at the Property, other
     than the Equipment, Modifications and other such items which are purchased
     with the proceeds of SPC Loans or Investor Contributions or which are
     otherwise required to be titled in the name of Lessor and excluding in all
     cases fixtures, and Lessor agrees, at Construction Agent's request and at
     Lessee's cost and expenses, to execute waiver forms, releases of Lessor
     Liens and other similar documentation (in form and substance reasonably
     satisfactory to Lessor and the Administrative Agent) in favor of any
     purchase money seller, lessor or lender who has financed or may finance in
     the future such items, with respect to such separately-financed items only.

          (c) Should any payment or distribution or security, or any proceeds
     thereof, be collected or received by the Construction Agent in respect of
     any indebtedness, liabilities or obligations of the Lessor to the
     Construction Agent, and such collection or receipt is not permitted under
     these subordination provisions of this Agreement, the Construction Agent
     shall immediately turn over such payment, distribution or security or
     proceeds to the Administrative Agent, in the form received, and, until so
     turned over, the same shall be held in trust by the Construction Agent as
     the property of the Lenders.

          (d) For purposes of this Agreement "subordinate and junior in right of
     payment" shall mean: no part of any subordinated indebtedness, liabilities
     or obligations shall have any claim to the assets of the Lessor on a parity
     with or prior to the claim of the Obligations or the principal amount of
     the Loans and other amounts due to the Administrative Agent, the Lenders
     and the Investor. Unless and until the Obligations shall have been fully
     paid and satisfied, the Construction Agent will not take, demand or
     receive, directly or indirectly, by set-off, redemption, purchase or in any
     manner, any payment or security for the whole or any part of any
     subordinated indebtedness, liabilities or obligations, and the Construction
     Agent will not accelerate the scheduled maturities of any amounts owing on
     account of such indebtedness, liabilities or obligations or demand payment
     thereof; provided that so long as no Default or Event of Default exists or
     would be in existence immediately after giving effect to such payment, the
     Construction Agent may receive currently scheduled payments on account of
     such indebtedness, liabilities and obligations.

                                      -16-
<PAGE>

          7.4 Right to Inspect. During the Construction Period, the Construction
          --------------------
     Agent shall upon reasonable written notice from the Lessor, permit the
     Lessor, the Administrative Agent acting on behalf of the Banks, and their
     respective authorized representatives to inspect the Property in accordance
     with Section 10.3 of Lease subject to this Construction Agency Agreement
     and the books and records of the Construction Agent relating to the
     Property during normal business hours, provided that such inspections shall
                                            --------
     be without notice in the event of an emergency.

          7.5 Costs and Fees. Except for such obligations, duties and
          ------------------
     requirements which are included as part of the Project Costs, all
     obligations, duties and requirements imposed upon or allocated to the
     Construction Agent shall be performed by the Construction Agent at the
     Construction's Agent's sole cost and expense. The Construction Agent will
     not be entitled to, and the Lessor shall have no obligation to pay, any
     agency fee, and the Construction Agent shall not be entitled to, and the
     Lessor shall have no obligation to make or pay, any reimbursement
     therefore, it being understood that this Agreement is being entered into as
     consideration for and as an inducement to the Lessor and the Construction
     Agent entering into the Lease and the other Operative Agreements.

                            SECTION 8. MISCELLANEOUS

          8.1 Notices. Unless otherwise specifically provided herein, all
          -----------
     notices, consents, directions, approvals, instructions, requests and other
     communications required or permitted by the terms hereof to be given to any
     Person to be effective shall be given in writing and in the manner provided
     in, and the effectiveness thereof shall be governed by the provisions of
     Section 14.3 of the Participation Agreement.

          From time to time any party may designate a new address for purposes
     of notice hereunder by notice to each of the other parties hereto.

          8.2 Successors and Assigns. This Agreement shall be binding upon and
          --------------------------
inure to the benefit of the Lessor, the Construction Agent and their respective
successors and assigns.

          8.3 GOVERNING LAW. THIS AGREEMENT AND THE RIGHTS AND OBLIGATIONS OF
          -----------------
THE PARTIES UNDER THIS AGREEMENT SHALL BE GOVERNED BY, AND CONSTRUED AND
INTERPRETED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK, EXCEPT TO THE
EXTENT THE LAWS OF THE STATE OF WASHINGTON ARE REQUIRED TO APPLY WITH RESPECT TO
THE PROPERTY AND ANY AGREEMENTS ENTERED INTO BY CONSTRUCTION AGENT IN SUCH STATE
PURSUANT TO THE AUTHORITY GRANTED IN SECTION 2.3 HEREOF.

          8.4 Amendments and Waivers. The Lessor and the Construction Agent may
          --------------------------
from time to time, enter into written amendments, supplements or modifications
hereto.

          8.5 Counterparts. This Agreement may be executed on any number of
          ----------------
separate counterparts and all of said counterparts taken together shall be
deemed to constitute one and the same instrument.

                                      -17-
<PAGE>

          8.6 Severability. Any provision of this Agreement which is prohibited
          ----------------
or unenforceable in any jurisdiction shall, as to such jurisdiction, be
ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining provisions hereof, and any such prohibition or
unenforceability in any jurisdiction shall not invalidate or render
unenforceable such provision in any other jurisdiction.

          8.7 Headings and Table of Contents. The headings and table of contents
          ----------------------------------
contained in this Agreement are for convenience of reference only and shall not
limit or otherwise affect the meaning hereof.

          8.8 Duty to Notify. To the extent that Lessor, as the owner of record
          ------------------
of the Property, receives any written notice, directions, instructions,
requests, demands or other communications from any third party or any
Governmental Authority relating to Construction Agent's rights and obligations
under this Agreement or the Lessee's rights and obligations under the Lease,
Lessor agrees to provide Construction Agent with prompt written notice of such,
including a true copy of all written materials received by Lessor relating
thereto.

          8.9 Liability of Wilmington Trust Company. It is expressly understood
          -----------------------------------------
and agreed by the parties hereto that (i) except as specifically provided for in
this Agreement, this Agreement is executed and delivered by Wilmington Trust
Company not individually or personally but solely as trustee of the Trust, in
the exercise of the powers and authority conferred and vested in it, (ii) each
of the representations, undertakings and agreements herein made on the part of
Lessor or Wilmington Trust Company, as the case may be, is made and intended not
as personal representations, undertakings and agreements by Wilmington Trust
Company but is made and intended for the purpose of binding only the Lessor,
(iii) except as specifically provided for in this Agreement nothing herein
contained shall be construed as creating any liability on Wilmington Trust
Company, individually or personally, to perform any covenant either expressed or
implied contained herein, all such liability, if any, being expressly waived by
the parties hereto and by any Person claiming by, through or under the parties
hereto and (iv) under no circumstances shall Wilmington Trust Company be
personally liable for the payment of any indebtedness or expenses of any party
hereto, or be liable for the breach or failure of any obligation,
representation, warranty or covenant made or undertaken by Lessor under this
Agreement; provided, however, the foregoing shall not limit Wilmington Trust
Company's liability for its own gross negligence or willful misconduct.

                                      -18-
<PAGE>

          IN WITNESS WHEREOF, the parties hereto have caused this Agreement to
be duly executed and delivered by their proper and duly authorized officers as
of the day and year first above written.

                                  IMMUNEX CORPORATION

                                  By:        /s/ David A. Mann
                                      ------------------------------------
                                      Name: David A. Mann
                                      Title: Executive Vice President, Chief
                                               Financial Officer and Treasurer

                                  IMMUNEX REAL ESTATE TRUST 2001

                                  By: Wilmington Trust Company, not in
                                      its individual capacity but solely
                                      as Trustee

                                      By:        /s/ Patricia Evans
                                          ---------------------------------
                                          Name: Patricia Evans
                                          Title: Senior Financial Services
                                                   Officer

                                      -19-

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