<PAGE>   1
                                                                    Exhibit 1.1
                                2,750,000 SHARES

                               CORIXA CORPORATION

                                  COMMON STOCK

                             UNDERWRITING AGREEMENT


                              September ___, 1997

LEHMAN BROTHERS INC.
INVEMED ASSOCIATES, INC.
VECTOR SECURITIES INTERNATIONAL, INC.
As Representatives of the several
  Underwriters named in Schedule 1,
c/o Lehman Brothers Inc.
Three World Financial Center
New York, New York 10285

Dear Sirs:

                 Corixa Corporation, a Delaware corporation (the "Company"),
proposes to sell 2,750,000 shares (the "Firm Stock") of the Company's Common
Stock, par value $0.001 per share (the "Common Stock").  In addition, the
Company proposes to grant to the Underwriters named in Schedule 1 hereto (the
"Underwriters") an option to purchase up to an additional 412,500 shares of the
Common Stock on the terms and for the purposes set forth in Section 2 (the
"Option Stock").  The Firm Stock and the Option Stock, if purchased, are
hereinafter collectively called the "Stock."  This is to confirm the agreement
concerning the purchase of the Stock from the Company by the Underwriters.

                 1.       Representations, Warranties and Agreements of the
Company.  The Company represents, warrants and agrees that:

                          (a)     A registration statement on Form S-1 with
                 respect to the Stock has (i) been prepared by the Company in
                 conformity with the requirements of the United States
                 Securities Act of 1933 (the "Securities Act") and the rules
                 and regulations (the "Rule and Regulations") of the United
                 States Securities and Exchange Commission (the "Commission")
                 thereunder, (ii) been filed with the Commission under the
                 Securities Act and (iii) become effective under the Securities
                 Act.  Copies of such registration statement and all the
                 amendments thereto have been delivered by the Company to you
                 as the representatives (the "Representatives") of the
                 Underwriters.  As used in this Agreement, "Effective Time"
                 means the date and the time as of which such registration
                 statement, or the most recent post-effective amendment
                 thereto, if any, was declared effective by the Commission;
                 "Effective Date" means the date of the Effective Time;
                 "Preliminary Prospectus" means each prospectus included in
                 such registration



                                       1.
<PAGE>   2
                 statement, or amendments thereof, before it became effective
                 under the Securities Act and any prospectus filed with the
                 Commission by the Company with the consent of the
                 Representatives pursuant to Rule 424(a) of the Rules and
                 Regulations; "Registration Statement" means such registration
                 statement, as amended at the Effective Time, including all
                 exhibits and financial statements and schedules, all
                 information contained in the final prospectus filed with the
                 Commission pursuant to Rule 424(b) of the Rules and
                 Regulations in accordance with Section 5(a) hereof and deemed
                 to be a part of the registration statement as of the Effective
                 Time pursuant to paragraph (b) of Rule 430A of the Rules and
                 Regulations and any registration statement filed pursuant to
                 Rule 462(b) of the Rules and Regulations; and "Prospectus"
                 means such final prospectus, as first filed with the
                 Commission pursuant to paragraph (1) or (4) of Rule 424(b) of
                 the Rules and Regulations.  The Commission has not issued any
                 order preventing or suspending the use of any Preliminary
                 Prospectus.

                          (b)     The Registration Statement conforms, and the
                 Prospectus and any further amendments or supplements to the
                 Registration Statement or the Prospectus will, when they
                 become effective or are filed with the Commission, as the case
                 may be, conform in all material respects to the requirements
                 of the Securities Act and the Rules and Regulations and do not
                 and will not, as of the applicable effective date (as to the
                 Registration Statement and any amendment thereto) and as of
                 the applicable filing date (as to the Prospectus and any
                 amendment or supplement thereto) contain an untrue statement
                 of a material fact or omit to state a material fact required
                 to be stated therein or necessary to make the statements
                 therein not misleading; provided that no representation or
                 warranty is made as to information contained in or omitted
                 from the Registration Statement or the Prospectus in reliance
                 upon and in conformity with written information furnished to
                 the Company through the Representatives by or on behalf of any
                 Underwriter specifically for inclusion therein.

                          (c)     The Company has been duly incorporated and is
                 validly existing as a corporation in good standing under the
                 laws of the state of Delaware, is duly qualified to do
                 business and is in good standing as a foreign corporation in
                 each jurisdiction in which its ownership or lease of property
                 or the conduct of its business requires such qualification,
                 except for jurisdictions in which the failure to so qualify
                 would not in the aggregate have a material adverse effect upon
                 the Company.  The Company has all requisite corporate power
                 and authority necessary to own or hold its properties and to
                 conduct its business as described in the Prospectus.

                          (d)     The Company has an authorized capitalization
                 as set forth in the Prospectus, and all of the issued and
                 outstanding shares of capital stock of the Company have been
                 duly and validly authorized and issued, are fully paid and
                 non- assessable and conform in all material respects to the
                 description thereof contained in the Prospectus.





                                       2.
<PAGE>   3
                          (e)     The unissued shares of the Stock to be issued
                 and sold by the Company to the Underwriters hereunder have
                 been duly and validly authorized and, when issued and
                 delivered against payment therefor as provided herein, will be
                 duly and validly issued, fully paid and non-assessable; and
                 the Stock will conform to the description thereof contained in
                 the Prospectus.

                          (f)     This Agreement has been duly authorized,
                 executed and delivered by the Company.

                          (g)     The execution, delivery and performance of
                 this Agreement by the Company and the consummation of the
                 transactions contemplated hereby will not conflict with or
                 result in a breach or violation of any of the terms or
                 provisions of, or constitute a default under, any indenture,
                 mortgage, deed of trust, loan agreement or other agreement or
                 instrument to which the Company is a party or by which the
                 Company is bound or to which any of the property or assets of
                 the Company is subject, except where such conflict, breach,
                 violation or default would not have a material adverse effect
                 on the financial position, stockholders' equity, results of
                 operations, business or prospects of the Company (hereinafter
                 a "Material Adverse Effect"), nor will such actions result in
                 any violation of the provisions of the charter or by-laws of
                 the Company or any statute, order, rule or regulation of any
                 court or governmental agency or body having jurisdiction over
                 the Company or any of its properties or assets; and except for
                 the registration of the Stock under the Securities Act and
                 such consents, approvals, authorizations, registrations or
                 qualifications as may be required under the Securities
                 Exchange Act of 1934 (the "Exchange Act") and applicable state
                 securities laws in connection with the purchase and
                 distribution of the Stock by the Underwriters, no consent,
                 approval, authorization or order of, or filing or registration
                 with, any such court or governmental agency or body is
                 required for the execution, delivery and performance of this
                 Agreement by the Company and the consummation of the
                 transactions contemplated hereby.

                          (h)     Except as described in the Prospectus, there
                 are no contracts, agreements or understandings between the
                 Company and any person granting such person the right (other
                 than rights which have been waived or satisfied) to require
                 the Company to file a registration statement under the
                 Securities Act with respect to any securities of the Company
                 owned or to be owned by such person or to require the Company
                 to include such securities in the securities registered
                 pursuant to the Registration Statement or in any securities
                 being registered pursuant to any other registration statement
                 filed by the Company under the Securities Act.

                          (i)     Except as described in the Prospectus, the
                 Company has not sold or issued any shares of Common Stock
                 during the six-month period preceding the date of the
                 Prospectus, including any sales pursuant to Rule 144A, or
                 Regulations D or S, of the Securities Act, other than shares
                 issued pursuant to





                                       3.
<PAGE>   4
                 employee benefit plans, qualified stock options plans or other
                 employee compensation plans or pursuant to outstanding
                 contractual obligations which have been disclosed in writing
                 to the Representatives, options, rights or warrants.

                          (j)     The Company has not sustained, since the date
                 of the latest audited financial statements included in the
                 Prospectus, any material loss or interference with its
                 business from fire, explosion, flood or other calamity,
                 whether or not covered by insurance, or from any labor dispute
                 or court or governmental action, order or decree, otherwise
                 than as set forth or contemplated in the Prospectus; and,
                 since such date, there has not been any material change in the
                 capital stock, or any change in the long-term debt (other than
                 pursuant to currently outstanding capital lease line
                 arrangements), of the Company or any material adverse change,
                 or any development involving a prospective material adverse
                 change, in or affecting the general affairs, management,
                 financial position, stockholders' equity or results of
                 operations of the Company, otherwise than as set forth or
                 contemplated in the Prospectus.

                          (k)     The financial statements (including the
                 related notes and supporting schedules) filed as part of the
                 Registration Statement or included in the Prospectus present
                 fairly the financial condition and results of operations of
                 the Company, at the dates and for the periods indicated, and
                 have been prepared in conformity with generally accepted
                 accounting principles applied on a consistent basis throughout
                 the periods involved.

                          (l)     Ernst & Young LLP, who have certified certain
                 financial statements of the Company, whose report appears in
                 the Prospectus and who have delivered the initial letter
                 referred to in Section 7(g) hereof, are independent public
                 accountants as required by the Securities Act and the Rules
                 and Regulations.

                          (m)     Except as described in the Prospectus, the
                 Company owns or possesses adequate rights to use all material
                 patents, patent applications, trademarks, service marks, trade
                 names, trademark registrations, service mark registrations,
                 copyrights and licenses necessary for the conduct of its
                 business as now conducted and has no reason to believe that
                 the conduct of its business will conflict with, and has not
                 received any notice of any claim of conflict with, any such
                 rights of others.

                          (n)     There are no legal or governmental
                 proceedings pending to which the Company is a party or of
                 which any property or assets of the Company is the subject
                 which are required to be described in the Prospectus and which
                 are not so described; and to the Company's knowledge, no such
                 proceedings are threatened or overtly contemplated by
                 governmental authorities or others.





                                       4.
<PAGE>   5
                          (o)     There are no contracts or other documents
                 which are required to be described in the Prospectus or filed
                 as exhibits to the Registration Statement by the Securities
                 Act or by the Rules and Regulations which have not been
                 described in the Prospectus or filed as exhibits to the
                 Registration Statement.

                          (p)     No relationship, direct or indirect, exists
                 between or among the Company on the one hand, and the
                 directors, officers, stockholders, customers or suppliers of
                 the Company on the other hand, which is required to be
                 described in the Prospectus which is not so described.

                          (q)     The Company (i) makes and keeps accurate
                 books and records in all material respects and (ii) maintains
                 internal accounting controls which provide reasonable
                 assurance that (A) all transactions are executed in accordance
                 with management's authorization, (B) all transactions are
                 recorded as necessary to permit preparation of its financial
                 statements and to maintain accountability for its assets, (C)
                 access to its assets is permitted only in accordance with
                 management's authorization and (D) the reported accountability
                 for its assets is compared with existing assets at reasonable
                 intervals.

                          (r)     The Company (i) is not in violation of its
                 charter or by-laws, (ii) is not in default in any material
                 respect, and no event has occurred which, with notice or lapse
                 of time or both, would constitute such a default, in the due
                 performance or observance of any term, covenant or condition
                 contained in any material indenture, mortgage, deed of trust,
                 loan agreement or other agreement or instrument to which it is
                 a party or by which it is bound or to which any of its
                 properties or assets is subject and (iii) is not in violation
                 of any law, ordinance, governmental rule, regulation or court
                 decree to which it or its property or assets is subject, the
                 effect of which violation in (iii) above would have a Material
                 Adverse Effect, and the Company or has not failed to obtain
                 any material license, permit, certificate, franchise or other
                 governmental authorization or permit necessary to the
                 ownership of its property or to the conduct of its business as
                 described in the Prospectus.

                 2.       Purchase of the Stock by the Underwriters.  On the
basis of the representations and warranties contained in, and subject to the
terms and conditions of, this Agreement, the Company agrees to sell 2,750,000
shares of the Firm Stock to the several Underwriters and each of the
Underwriters, severally and not jointly, agrees to purchase the number of
shares of the Firm Stock set opposite that Underwriter's name in Schedule 1
hereto.  The respective purchase obligations of the Underwriters with respect
to the Firm Stock shall be rounded among the Underwriters to avoid fractional
shares, as the Representatives may determine.

                 In addition, the Company grants to the Underwriters an option
to purchase up to 412,500 shares of Option Stock.  Such option is granted
solely for the purpose of covering over-allotments in the sale of Firm Stock
and is exercisable as provided in Section 4 hereof.





                                       5.
<PAGE>   6
Shares of Option Stock shall be purchased severally for the account of the
Underwriters in proportion to the number of shares of Firm Stock set opposite
the name of such Underwriters in Schedule 1 hereto.  The respective purchase
obligations of each Underwriter with respect to the Option Stock shall be
adjusted by the Representatives so that no Underwriter shall be obligated to
purchase Option Stock other than in 100 share amounts.  The price of both the
Firm Stock and any Option Stock shall be $_____ per share.

                 The Company shall not be obligated to deliver any of the Stock
to be delivered on the First Delivery Date or the Second Delivery Date (as
hereinafter defined), as the case may be, except upon payment for all the Stock
to be purchased on such Delivery Date as provided herein.

                 3.       Offering of Stock by the Underwriters.  Upon
authorization by the Representatives of the release of the Firm Stock, the
several Underwriters propose to offer the Firm Stock for sale upon the terms
and conditions set forth in the Prospectus.

                 It is understood that 137,500 shares of the Firm Stock will
initially be reserved by the several Underwriters for offer and sale upon the
terms and conditions set forth in the Prospectus and in accordance with the
rules and regulations of the National Association of Securities Dealers, Inc.
to employees and persons having business relationships with the Company who
have heretofore delivered to the Representatives offers or indications of
interest to purchase shares of Firm Stock in form satisfactory to the
Representatives, and that any allocation of such Firm Stock among such persons
will be made in accordance with timely directions received by the
Representatives from the Company; provided, that under no circumstances will
the Representatives or any Underwriter be liable to the Company or to any such
person for any action taken or omitted in good faith in connection with such
offering to employees and persons having business relationships with the
Company.  It is further understood that any shares of such Firm Stock which are
not purchased by such persons will be offered by the Underwriters to the public
upon the terms and conditions set forth in the Prospectus.

                 4.       Delivery of and Payment for the Stock.  Delivery of
and payment for the Firm Stock shall be made at the office of Venture Law
Group, 4750 Carillon Point, Kirkland, Washington, at 10:00 A.M., New York City
time, on the fourth full business day following the date of this Agreement or
at such other date or place as shall be determined by agreement between the
Representatives and the Company.  This date and time are sometimes referred to
as the "First Delivery Date."  On the First Delivery Date, the Company shall
deliver or cause to be delivered certificates representing the Firm Stock to
the Representatives for the account of each Underwriter against payment to or
upon the order of the Company of the purchase price by federal funds wire
transfer.  Such payment shall be made upon delivery of the Firm Stock to the
Representatives for the respective accounts of the several Underwriters
(including, without limitation, by "full-fast" electronic transfer by
Depository Trust Company) against receipt therefor signed by Lehman Brothers
Inc.  Time shall be of the essence, and delivery at the time and place
specified pursuant to this Agreement is a further condition of the obligation
of each Underwriter hereunder.  Upon delivery, the Firm Stock shall be
registered in such names and in such denominations as the Representatives shall
request in writing not less than two full





                                       6.
<PAGE>   7
business days prior to the First Delivery Date.  For the purpose of expediting
the checking and packaging of the certificates for the Stock, the Company shall
make the certificates representing the Firm Stock available for inspection by
the Representatives in New York, New York, not later than 2:00 P.M., New York
City time, on the business day prior to the First Delivery Date.

                 At any time on or before the thirtieth day after the date of
this Agreement the option granted in Section 2 may be exercised by written
notice being given to the Company by the Representatives.  Such notice shall
set forth the aggregate number of shares of Option Stock as to which the option
is being exercised, the names in which the shares of Option Stock are to be
registered, the denominations in which the shares of Option Stock are to be
issued and the date and time, as determined by the Representatives, when the
shares of Option Stock are to be delivered; provided, however, that this date
and time shall not be earlier than the First Delivery Date nor earlier than the
second business day after the date on which the option shall have been
exercised nor later than the fifth business day after the date on which the
option shall have been exercised.  The date and time the shares of Option Stock
are delivered are sometimes referred to as the "Second Delivery Date" and the
First Delivery Date and the Second Delivery Date are sometimes each referred to
as a "Delivery Date".

                 Delivery of and payment for the Option Stock shall be made at
the place specified in the first sentence of the first paragraph of this
Section 4 (or at such other place as shall be determined by agreement between
the Representatives and the Company) at 10:00 A.M., New York City time, on the
Second Delivery Date.  On the Second Delivery Date, the Company shall deliver
or cause to be delivered the certificates representing the Option Stock to the
Representatives for the account of each Underwriter against payment to or upon
the order of the Company of the purchase price by federal funds wire transfer.
Such payment shall be made upon delivery of the Firm Stock to the
Representatives for the respective accounts of the several Underwriters
(including, without limitation, by "full-fast" electronic transfer by
Depository Trust Company) against receipt therefor signed by Lehman Brothers
Inc.  Time shall be of the essence, and delivery at the time and place
specified pursuant to this Agreement is a further condition of the obligation
of each Underwriter hereunder.  Upon delivery, the Option Stock shall be
registered in such names and in such denominations as the Representatives shall
request in the aforesaid written notice.  For the purpose of expediting the
checking and packaging of the certificates for the Option Stock, the Company
shall make the certificates representing the Option Stock available for
inspection by the Representatives in New York, New York, not later than 2:00
P.M., New York City time, on the business day prior to the Second Delivery
Date.





                                       7.
<PAGE>   8
                 5.       Further Agreements of the Company.  The Company
agrees:

                          (a)     To prepare the Prospectus in a form approved
                 by the Representatives and to file such Prospectus pursuant to
                 Rule 424(b) under the Securities Act not later than
                 Commission's close of business on the second business day
                 following the execution and delivery of this Agreement or, if
                 applicable, such earlier time as may be required by Rule
                 430A(a)(3) under the Securities Act; to make no further
                 amendment or any supplement to the Registration Statement or
                 to the Prospectus except as permitted herein; to advise the
                 Representatives, promptly after it receives notice thereof, of
                 the time when any amendment to the Registration Statement has
                 been filed or becomes effective or any supplement to the
                 Prospectus or any amended Prospectus has been filed and to
                 furnish the Representatives with copies thereof; to advise the
                 Representatives, promptly after it receives notice thereof, of
                 the issuance by the Commission of any stop order or of any
                 order preventing or suspending the use of any Preliminary
                 Prospectus or the Prospectus, of the suspension of the
                 qualification of the Stock for offering or sale in any
                 jurisdiction, of the initiation or threatening of any
                 proceeding for any such purpose, or of any request by the
                 Commission for the amending or supplementing of the
                 Registration Statement or the Prospectus or for additional
                 information; and, in the event of the issuance of any stop
                 order or of any order preventing or suspending the use of any
                 Preliminary Prospectus or the Prospectus or suspending any
                 such qualification, to use promptly its best efforts to obtain
                 its withdrawal;

                          (b)     To furnish promptly to each of the
                 Representatives and to counsel for the Underwriters a signed
                 copy of the Registration Statement as originally filed with
                 the Commission, and each amendment thereto filed with the
                 Commission, including all consents and exhibits filed
                 therewith;

                          (c)     To deliver promptly to the Representatives
                 such number of the following documents as the Representatives
                 shall reasonably request:  (i) conformed copies of the
                 Registration Statement as originally filed with the Commission
                 and each amendment thereto (in each case excluding exhibits
                 other than this Agreement and (ii) each Preliminary
                 Prospectus, the Prospectus and any amended or supplemented
                 Prospectus; and, if the delivery of a prospectus is required
                 at any time after the Effective Time in connection with the
                 offering or sale of the Stock or any other securities relating
                 thereto and if at such time any events shall have occurred as
                 a result of which the Prospectus as then amended or
                 supplemented would include an untrue statement of a material
                 fact or omit to state any material fact necessary in order to
                 make the statements therein, in the light of the circumstances
                 under which they were made when such Prospectus is delivered,
                 not misleading, or, if for any other reason it shall be
                 necessary to amend or supplement the Prospectus in order to
                 comply with the Securities Act, to notify the Representatives
                 and, upon their request, to file such document and to prepare
                 and furnish without charge to each Underwriter and to





                                       8.
<PAGE>   9
                 any dealer in securities as many copies as the Representatives
                 may from time to time reasonably request of an amended or
                 supplemented Prospectus which will correct such statement or
                 omission or effect such compliance.

                          (d)     To file promptly with the Commission any
                 amendment to the Registration Statement or the Prospectus or
                 any supplement to the Prospectus that may, in the judgment of
                 the Company or the Representatives, be required by the
                 Securities Act or requested by the Commission;

                          (e)     Prior to filing with the Commission any
                 amendment to the Registration Statement or supplement to the
                 Prospectus or any Prospectus pursuant to Rule 424 of the Rules
                 and Regulations, to furnish a copy thereof to the
                 Representatives and counsel for the Underwriters and obtain
                 the consent of the Representatives to the filing;

                          (f)     As soon as practicable after the Effective
                 Date, to make generally available to the Company's security
                 holders and to deliver to the Representatives an earnings
                 statement of the Company (which need not be audited) complying
                 with Section 11(a) of the Securities Act and the Rules and
                 Regulations (including, at the option of the Company, Rule
                 158);

                          (g)     For a period of five years following the
                 Effective Date, to furnish to the Representatives copies of
                 all materials furnished by the Company to its shareholders and
                 all public reports and all reports and financial statements
                 furnished by the Company to the principal national securities
                 exchange upon which the Common Stock may be listed pursuant to
                 requirements of or agreements with such exchange or to the
                 Commission pursuant to the Exchange Act or any rule or
                 regulation of the Commission thereunder;

                          (h)     For a period of five years following the
                 Effective Date, promptly from time to time to take such action
                 as the Representatives may reasonably request to qualify the
                 Stock for offering and sale under the securities laws of such
                 jurisdictions as the Representatives may request and to comply
                 with such laws so as to permit the continuance of sales and
                 dealings therein in such jurisdictions for as long as may be
                 necessary to complete the distribution of the Stock; provided
                 that in connection therewith the Company shall not be required
                 to qualify as a foreign corporation or to file a general
                 consent to service of process in any jurisdiction;

                          (i)     For a period of 180 days from the Effective
                 Date, not to, directly or indirectly, (1) offer for sale,
                 sell, pledge or otherwise dispose of (or enter into any
                 transaction or device which is designed to, or could be
                 expected to, result in the disposition by any person at any
                 time in the future of) any shares of Common Stock or
                 securities convertible into or exchangeable for Common Stock
                 (other than the Stock and shares issued pursuant to employee
                 benefit plans, qualified





                                       9.
<PAGE>   10
                 stock option plans or other employee compensation plans
                 existing on the date hereof or pursuant to currently
                 outstanding contractual obligations, options, warrants or
                 rights), or sell or grant options, rights or warrants with
                 respect to any shares of Common Stock or securities
                 convertible into or exchangeable for Common Stock (other than
                 the grant of options pursuant to option plans existing on the
                 date hereof or pursuant to currently outstanding contractual
                 obligations), or (2) enter into any swap or other derivatives
                 transaction that transfers to another, in whole or in part,
                 any of the economic benefits or risks of ownership of such
                 shares of Common Stock, whether any such transaction described
                 in clause (1) or (2) above is to be settled by delivery of
                 Common Stock or other securities, in cash or otherwise, in
                 each case without the prior written consent of Lehman Brothers
                 Inc.; provided that notwithstanding the foregoing, in
                 connection with corporate partnerships and other collaborative
                 arrangements that the Company may enter into during such 180
                 day period, the Company shall be allowed to issue, offer for
                 sale, sell, pledge or otherwise dispose of (or enter into any
                 transaction or device which is designed to, or could be
                 expected to, result in the disposition by any person at any
                 time in the future of) shares of Common Stock and securities
                 convertible into or exchangeable for Common Stock, and to sell
                 or grant options, rights, or warrants with respect to shares
                 of Common Stock and securities convertible into or
                 exchangeable for Common Stock to such corporate partners or
                 collaborators, or designees thereof, without the prior written
                 consent of Lehman Brothers Inc.; provided further, that any
                 such corporate partner or collaborator, or designee thereof,
                 will be bound by and subject to the restrictions set forth in
                 this Section 5(i) for the remainder of such 180 day period;

                          (j)     To cause each officer, director and
                 stockholder holding more than 1% of the outstanding securities
                 of the Company to furnish to the Representatives, prior to the
                 First Delivery Date, a letter or letters, in form and
                 substance reasonably satisfactory to counsel for the
                 Underwriters, pursuant to which each such person shall agree
                 not to offer, sell, contract to sell, make any short sale
                 (including, but not limited to, a "short against the box"),
                 pledge, or otherwise dispose of, directly or indirectly, any
                 shares of Common Stock or securities convertible into or
                 exchangeable for Common Stock for a period of 180 days from
                 the Effective Date, without the prior written consent of
                 Lehman Brothers Inc.;

                          (k)     Prior to the Effective Date, to apply for the
                 inclusion of the Stock on the Nasdaq National Market System
                 and to use its best efforts to complete that listing, subject
                 only to official notice of issuance, prior to the First
                 Delivery Date;

                          (l)     To apply the net proceeds from the sale of
                 the Stock being sold by the Company as set forth in the
                 Prospectus; and

                          (m)     To take such reasonable steps as shall be
                 necessary to ensure that the Company shall not become an
                 "investment company" within the meaning of





                                      10.
<PAGE>   11
                 such term under the Investment Company Act of 1940 and the
                 rules and regulations of the Commission thereunder.

                 6.       Expenses.  The Company agrees to pay (a) the costs
incident to the authorization, issuance, sale and delivery of the Stock and any
taxes payable in that connection; (b) the costs incident to the preparation,
printing and filing under the Securities Act of the Registration Statement and
any amendments and exhibits thereto; (c) the costs of distributing the
Registration Statement as originally filed and each amendment thereto and any
post-effective amendments thereof (including, in each case, exhibits), any
Preliminary Prospectus, the Prospectus and any amendment or supplement to the
Prospectus, all as provided in this Agreement; (d) the costs of producing and
distributing this Agreement and any other related documents in connection with
the offering, purchase, sale and delivery of the Stock; (e) the filing fees
incident to securing any required review by the National Association of
Securities Dealers, Inc. of the terms of sale of the Stock; (f) any applicable
listing or other fees; (g) the fees and expenses of qualifying the Stock under
the securities laws of the several jurisdictions as provided in Section 5(h)
and of preparing, printing and distributing a Blue Sky Memorandum (including
related fees and expenses of counsel to the Underwriters); (h) all costs and
expenses of the Underwriters, including the fees and disbursements of counsel
for the Underwriters, incident to the offer and sale of shares of the Stock by
the Underwriters to employees and persons having business relationships with
the Company and its subsidiaries, as described in Section 3; and (i) all other
costs and expenses incident to the performance of the obligations of the
Company under this Agreement; provided that, except as provided in this Section
6 and in Section 11 the Underwriters shall pay their own costs and expenses,
including the costs and expenses of their counsel, any transfer taxes on the
Stock which they may sell and the expenses of advertising any offering of the
Stock made by the Underwriters.

                 7.       Conditions of Underwriters' Obligations.  The
respective obligations of the Underwriters hereunder are subject to the
accuracy, when made and on each Delivery Date, of the representations and
warranties of the Company contained herein, to the performance by the Company
of its obligations hereunder, and to each of the following additional terms and
conditions:

                          (a)     The Prospectus shall have been timely filed
                 with the Commission in accordance with Section 5(a); no stop
                 order suspending the effectiveness of the Registration
                 Statement or any part thereof shall have been issued and no
                 proceeding for that purpose shall have been initiated or
                 threatened by the Commission; and any request of the
                 Commission for inclusion of additional information in the
                 Registration Statement or the Prospectus or otherwise shall
                 have been complied with.

                          (b)     No Underwriter shall have discovered and
                 disclosed to the Company on or prior to such Delivery Date
                 that the Registration Statement or the Prospectus or any
                 amendment or supplement thereto contains an untrue statement
                 of a fact which, in the opinion of Cooley Godward LLP, counsel
                 for the Underwriters, is material or omits to state a fact
                 which, in the opinion of such





                                      11.
<PAGE>   12
                 counsel, is material and is required to be stated therein or
                 is necessary to make the statements therein not misleading.

                          (c)     All corporate proceedings and other legal
                 matters incident to the authorization, form and validity of
                 this Agreement, the Stock, the Registration Statement and the
                 Prospectus, and all other legal matters relating to this
                 Agreement and the transactions contemplated hereby shall be
                 reasonably satisfactory in all material respects to counsel
                 for the Underwriters, and the Company shall have furnished to
                 such counsel all documents and information that they may
                 reasonably request to enable them to pass upon such matters.

                          (d)     Venture Law Group shall have furnished to the
                 Representatives its written opinion, as counsel to the
                 Company, addressed to the Underwriters and dated such Delivery
                 Date, in form and substance reasonably satisfactory to the
                 counsel for the Underwriters, to the effect that:

                                  (i)      The Company has been duly
                          incorporated and is validly existing as a corporation
                          in good standing under the laws of the state of
                          Delaware, is duly qualified to do business and is
                          validly existing as a foreign corporation in each
                          jurisdiction in which its ownership or lease of
                          property or the conduct of its business requires such
                          qualification, except for jurisdictions in which the
                          failure to so qualify would not in the aggregate have
                          a material adverse effect on the Company.  The
                          Company has all requisite corporate authority
                          necessary to own or hold its properties and conduct
                          its business as described in the Prospectus;

                                  (ii)     The Company has an authorized
                          capitalization as set forth in the Prospectus, and
                          all of the issued and outstanding shares of capital
                          stock of the Company have been duly and validly
                          authorized and issued, are fully paid and
                          non-assessable and conform in all material respects
                          to the description thereof contained in the
                          Prospectus, and the shares of Stock being delivered
                          on such Delivery Date have been duly and validly
                          authorized and, when delivered by the Company in
                          accordance with the terms hereof, will be duly and
                          validly issued, fully paid and non-assessable and
                          conform in all material respects to the description
                          thereof contained in the Prospectus;

                                  (iii)    There are no preemptive or other
                          rights to subscribe for or to purchase, nor any
                          restriction upon the voting or transfer of, any
                          shares of the Stock pursuant to the Company's charter
                          or by-laws or any agreement or other instrument known
                          to such counsel;

                                  (iv)     To such counsel's knowledge and
                          other than as set forth in the Prospectus, there are
                          no legal or governmental proceedings pending to which
                          the Company is a party or of which any property or
                          assets of the





                                      12.
<PAGE>   13
                          Company is the subject which are required to be
                          described in the Prospectus and which are not so
                          described; and, to such counsel's knowledge, no such
                          proceedings are threatened by governmental
                          authorities or others;

                                  (v)      The Registration Statement was
                          declared effective under the Securities Act as of the
                          date and time specified in such opinion, the
                          Prospectus was filed with the Commission pursuant to
                          the subparagraph of Rule 424(b) of the Rules and
                          Regulations specified in such opinion on the date
                          specified therein and, to such counsel's knowledge,
                          no stop order suspending the effectiveness of the
                          Registration Statement has been issued and, to such
                          counsel's knowledge, no proceeding for that purpose
                          is pending or threatened by the Commission;

                                  (vi)     The Registration Statement and the
                          Prospectus and any further amendments or supplements
                          thereto made by the Company prior to such Delivery
                          Date (other than the financial statements (including
                          supporting schedules) and financial data derived
                          therefrom, and other financial data and statistical
                          information included therein, as to which such
                          counsel need express no opinion) comply as to form in
                          all material respects with the requirements of the
                          Securities Act and the Rules and Regulations;

                                  (vii)    The statements (a) in the Prospectus
                          under captions "Certain Transactions," "Description of
                          Capital Stock" and "Shares Eligible for Future Sale,"
                          and (b) in the Registration Statement in Part II,
                          Items 14 and 15, in each case insofar as such
                          statements constitute summaries of the legal matters,
                          documents or proceedings set forth therein, fairly
                          present in all material respects the information
                          called for with respect to such legal matters,
                          documents and proceedings and fairly summarize in all
                          material respects the matters referred to therein;

                                  (viii)   To such counsel's knowledge, there
                          are no contracts or other documents which are
                          required to be described in the Prospectus or filed
                          as exhibits to the Registration Statement by the
                          Securities Act or by the Rules and Regulations which
                          have not been described or filed as exhibits to the
                          Registration Statement or incorporated therein by
                          reference as permitted by the Rules and Regulations;

                                  (ix)     This Agreement has been duly
                          authorized, executed and delivered by the Company;

                                  (x)      The issue and sale of the shares of
                          Stock being delivered on such Delivery Date by the
                          Company and the compliance by the Company with all of
                          the provisions of this Agreement and the consummation
                          of the





                                      13.
<PAGE>   14
                          transactions contemplated hereby (other than the
                          indemnification and contribution obligations of the
                          Company hereunder, as to which such counsel need
                          express no opinion) will not conflict with or result
                          in a breach or violation of any of the terms or
                          provisions of, or constitute a default under, any
                          indenture, mortgage, deed of trust, loan agreement or
                          other agreement or instrument known to such counsel
                          to which the Company is a party or by which the
                          Company is bound or to which any of the property or
                          assets of the Company is subject and which is filed
                          as an exhibit to the Registration Statement, nor will
                          such actions result in any violation of the
                          provisions of the charter or by-laws of the Company
                          or any statute, order, rule or regulation known to
                          such counsel of any court or governmental agency or
                          body having jurisdiction over the Company or any of
                          its properties or assets; and, except for the
                          registration of the Stock under the Securities Act
                          and such consents, approvals, authorizations,
                          registrations or qualifications as may be required
                          under the Exchange Act and applicable state
                          securities laws in connection with the purchase and
                          distribution of the Stock by the Underwriters, no
                          consent, approval, authorization or order of, or
                          filing or registration with, any such court or
                          governmental agency or body is required for the
                          execution, delivery and performance of this Agreement
                          by the Company and the consummation of the
                          transactions contemplated hereby; and

                                  (xi)     To the best of such counsel's
                          knowledge, except as described in the Prospectus,
                          there are no contracts, agreements or understandings
                          between the Company and any person granting such
                          person the right (other than rights which have been
                          waived or satisfied) to require the Company to file a
                          registration statement under the Securities Act with
                          respect to any securities of the Company owned or to
                          be owned by such person or to require the Company to
                          include such securities in the securities registered
                          pursuant to the Registration Statement or in any
                          securities being registered pursuant to any other
                          registration statement filed by the Company under the
                          Securities Act.

                 In rendering such opinion, such counsel may state that its
                 opinion is limited to matters governed by the Federal laws of
                 the United States of America, the laws of the State of
                 Washington and the General Corporation Law of the State of
                 Delaware and that such counsel is not admitted in the State of
                 Delaware.  Such counsel shall also have furnished to the
                 Representatives a written statement, addressed to the
                 Underwriters and dated such Delivery Date, in form and
                 substance reasonably satisfactory to the Representatives, to
                 the effect that (x) such counsel has acted as counsel to the
                 Company on a regular basis (although the Company is also
                 represented by its Corporate Counsel and, with respect to
                 patent and certain other intellectual property matters by
                 other outside counsel), has acted as counsel to the Company in
                 connection with previous financing transactions and has acted
                 as counsel to the Company in connection with the preparation
                 of the





                                      14.
<PAGE>   15
                 Registration Statement, and (y) based on the foregoing, no
                 facts have come to the attention of such counsel which lead it
                 to believe that the Registration Statement, as of the
                 Effective Date, contained any untrue statement of a material
                 fact or omitted to state a material fact required to be stated
                 therein or necessary in order to make the statements therein,
                 in light of the circumstances in which they were made, not
                 misleading (except with respect to the financial statements
                 (including supporting schedules) and financial data derived
                 therefrom, and other financial data and statistical
                 information included therein, as to which no such statement
                 need be expressed), or that the Prospectus contains any untrue
                 statement of a material fact or omits to state a material fact
                 required to be stated therein or necessary in order to make
                 the statements therein, in light of the circumstances under
                 which they were made, not misleading (except with respect to
                 the financial statements (including supporting schedules) and
                 financial data derived therefrom, and other financial data and
                 statistical information included therein, as to which no such
                 statement need be expressed).  The foregoing opinion and
                 statement may be qualified by a statement to the effect that
                 such counsel does not assume any responsibility for the
                 accuracy, completeness or fairness of the statements contained
                 in the Registration Statement or the Prospectus except for the
                 statements made in the Prospectus under the captions "Shares
                 Eligible For Future Sale" and "Description of Capital Stock",
                 insofar as such statements relate to the Stock and concern
                 legal matters.

                          (e)     Seed and Berry LLP shall have furnished to
                 the Representatives its written opinion as patent counsel to
                 the Company addressed to the Underwriters and dated such
                 Delivery Date, in form and substance reasonably satisfactory
                 to the Representatives, to the effect that:

                                  (i)      the statements in the Registration
                          Statement and the Prospectus under the captions "Risk
                          Factors -- Dependence on Proprietary Technology and
                          Uncertainty of Patent Protection" and "Business --
                          Patents and Proprietary Technology" and certain
                          specified statements under the caption "Business"
                          generally, to the extent such statements constitute a
                          description or summary of the legal matters, documents
                          or proceedings relating to patent matters on which
                          such counsel has represented the Company (the
                          "Representation") and to the extent such legal
                          matters, documents or proceedings have been disclosed
                          to such counsel, are accurate and complete statements
                          and nothing has come to such counsel's attention that
                          causes such counsel to believe that such sections of
                          the Registration Statement and the Prospectus contain
                          any untrue statement of a material fact or omit to
                          state a material fact required to be stated therein or
                          necessary in order to make the statements therein, in
                          light of the circumstances under which they were made,
                          not misleading;

                                  (ii)     to the best of such counsel's
                          knowledge there are no legal or governmental
                          proceedings pending relating to patent rights, trade





                                      15.
<PAGE>   16
                          secrets, trademarks, service marks or other
                          proprietary information or materials of the Company,
                          and to the best of such counsel's knowledge no such
                          proceedings are threatened or contemplated by
                          governmental authorities or others;

                                  (iii)    based solely upon a review of
                          matters which counsel has been engaged to provide
                          direct substantive attention, such counsel has no
                          reason to believe that the Company is infringing or
                          otherwise violating any patents, trade secrets,
                          trademarks, service marks or other proprietary rights
                          of others, and to the best of such counsel's
                          knowledge there are no infringements by others of any
                          of the Company's patents, trade secrets, trademarks,
                          service marks or other proprietary information or
                          materials which in the judgment of such counsel could
                          affect materially the use thereof by the Company; and

                                  (iv)     based solely upon a review of
                          matters which counsel has been engaged to provide
                          direct substantive attention, such counsel has no
                          reason to believe that the Company does not own or
                          possess adequate licenses or other rights to use all
                          material patents, patent applications and trademarks
                          described in the Prospectus and necessary to conduct
                          the business now being conducted by the Company as
                          described in the Prospectus.

                          (f)     The Representatives shall have received from
                 Cooley Godward LLP, counsel for the Underwriters, such opinion
                 or opinions, dated such Delivery Date, with respect to the
                 issuance and sale of the Stock, the Registration Statement,
                 the Prospectus and other related matters as the
                 Representatives may reasonably require, and the Company shall
                 have furnished to such counsel such documents as they
                 reasonably request for the purpose of enabling them to pass
                 upon such matters.

                          (g)     At the time of execution of this Agreement,
                 the Representatives shall have received from Ernst & Young
                 LLP, a letter, in form and substance satisfactory to the
                 Representatives, addressed to the Underwriters and dated the
                 date hereof (i) confirming that they are independent public
                 accountants within the meaning of the Securities Act and are
                 in compliance with the applicable requirements relating to the
                 qualification of accountants under Rule 2-01 of Regulation S-X
                 of the Commission, (ii) stating, as of the date hereof (or,
                 with respect to matters involving changes or developments
                 since the respective dates as of which specified financial
                 information is given in the Prospectus, as of a date not more
                 than five days prior to the date hereof), the conclusions and
                 findings of such firm with respect to the financial
                 information and other matters ordinarily covered by
                 accountants' "comfort letters" to underwriters in connection
                 with registered public offerings.





                                      16.
<PAGE>   17
                          (h)     With respect to the letter of referred to in
                 the preceding paragraph and delivered to the Representatives
                 concurrently with the execution of this Agreement (the
                 "initial letter"), the Company shall have furnished to the
                 Representatives a letter (the "bring-down letter") of such
                 accountants, addressed to the Underwriters and dated such
                 Delivery Date (i) confirming that they are independent public
                 accountants within the meaning of the Securities Act and are
                 in compliance with the applicable requirements relating to the
                 qualification of accountants under Rule 2-01 of Regulation S-X
                 of the Commission, (ii) stating, as of the date of the
                 bring-down letter (or, with respect to matters involving
                 changes or developments since the respective dates as of which
                 specified financial information is given in the Prospectus, as
                 of a date not more than five days prior to the date of the
                 bring-down letter), the conclusions and findings of such firm
                 with respect to the financial information and other matters
                 covered by the initial letter and (iii) confirming in all
                 material respects the conclusions and findings set forth in
                 the initial letter.

                          (i)     The Company shall have furnished to the
                 Representatives a certificate, dated such Delivery Date, of
                 its Chairman of the Board, its President or a Vice President
                 and its Vice President of Finance and Administration stating
                 that:

                                  (i)      The representations, warranties and
                          agreements of the Company in Section 1 are true and
                          correct as of such Delivery Date; the Company has
                          complied with all its agreements contained herein;
                          and the conditions set forth in Sections 7(a) and
                          7(j) have been fulfilled; and

                                  (ii)     They have carefully examined the
                          Registration Statement and the Prospectus and, in
                          their opinion (A) as of the Effective Date, the
                          Registration Statement and Prospectus did not include
                          any untrue statement of a material fact and did not
                          omit to state a material fact required to be stated
                          therein or necessary to make the statements therein
                          not misleading, and (B) since the Effective Date no
                          event has occurred which should have been set forth
                          in a supplement or amendment to the Registration
                          Statement or the Prospectus.

                          (j)     (i)  The Company shall not have sustained
                 since the date of the latest audited financial statements
                 included in the Prospectus any loss or interference with its
                 business from fire, explosion, flood or other calamity,
                 whether or not covered by insurance, or from any labor dispute
                 or court or governmental action, order or decree, otherwise
                 than as set forth or contemplated in the Prospectus or (ii)
                 since such date there shall not have been any change in the
                 capital stock or long-term debt of the Company or any change,
                 or any development involving a prospective change, in or
                 affecting the general affairs, management, financial position,
                 stockholders' equity or results of operations of the Company,
                 otherwise than as set forth or contemplated in the Prospectus,
                 the





                                      17.
<PAGE>   18
                 effect of which, in any such case described in clause (i) or
                 (ii), is, in the judgment of the Representatives, so material
                 and adverse as to make it impracticable or inadvisable to
                 proceed with the public offering or the delivery of the Stock
                 being delivered on such Delivery Date on the terms and in the
                 manner contemplated in the Prospectus.

                          (k)     Subsequent to the execution and delivery of
                 this Agreement there shall not have occurred any of the
                 following:  (i) trading in securities generally on the New
                 York Stock Exchange or the American Stock Exchange or in the
                 over-the-counter market, or trading in any securities of the
                 Company on any exchange or in the over-the-counter market,
                 shall have been suspended or minimum prices shall have been
                 generally established on any such exchange or such market by
                 the Commission, by such exchange or by any other regulatory
                 body or governmental authority having jurisdiction, (ii) a
                 general banking moratorium shall have been declared by Federal
                 or New York or Washington State authorities, (iii) the United
                 States shall have become engaged in active hostilities, there
                 shall have been an escalation in active hostilities involving
                 the United States or there shall have been a declaration of a
                 national emergency or war by the United States or (iv) there
                 shall have occurred such a material adverse change in general
                 economic, political or financial conditions (or the effect of
                 international conditions on the financial markets in the
                 United States shall be such) as to make it, in the judgment of
                 a majority in interest of the several Underwriters,
                 impracticable or inadvisable to proceed with the public
                 offering or delivery of the Stock being delivered on such
                 Delivery Date on the terms and in the manner contemplated in
                 the Prospectus.

                          (l)     The Nasdaq National Market System shall have
                 approved the Stock for inclusion, subject only to official
                 notice of issuance and evidence of satisfactory distribution.

                 All opinions, letters, evidence and certificates mentioned
above or elsewhere in this Agreement shall be deemed to be in compliance with
the provisions hereof only if they are in form and substance reasonably
satisfactory to counsel for the Underwriters.

                 8.       Indemnification and Contribution.

                          (a)     The Company shall indemnify and hold harmless
                 each Underwriter its officers and employees and each person,
                 if any, who controls any Underwriter within the meaning of the
                 Securities Act, from and against any loss, claim, damage or
                 liability, joint or several, or any action in respect thereof
                 (including, but not limited to, any loss, claim, damage,
                 liability or action relating to purchases and sales of Stock),
                 to which that Underwriter, officer, employee or controlling
                 person may become subject, under the Securities Act or
                 otherwise, insofar as such loss, claim, damage, liability or
                 action arises out of, or is based upon, (i) any untrue
                 statement or alleged untrue statement of a material fact





                                      18.
<PAGE>   19
                 contained (A) in any Preliminary Prospectus, the Registration
                 Statement or the Prospectus or in any amendment or supplement
                 thereto or (B) in any blue sky application or other document
                 prepared or executed by the Company (or based upon any written
                 information furnished by the Company) specifically for the
                 purpose of qualifying any or all of the Stock under the
                 securities laws of any state or other jurisdiction (any such
                 application, document or information being hereinafter called
                 a "Blue Sky Application"), (ii) the omission or alleged
                 omission to state in any Preliminary Prospectus, the
                 Registration Statement or the Prospectus, or in any amendment
                 or supplement thereto, or in any Blue Sky Application any
                 material fact required to be stated therein or necessary to
                 make the statements therein not misleading or (iii) any act or
                 failure to act or any alleged act or failure to act by any
                 Underwriter in connection with, or relating in any manner to,
                 the Stock or the offering contemplated hereby, and which is
                 included as part of or referred to in any loss, claim, damage,
                 liability or action arising out of or based upon matters
                 covered by clause (i) or (ii) above (provided that the Company
                 shall not be liable under this clause (iii) to the extent that
                 it is determined in a final judgment by a court of competent
                 jurisdiction that such loss, claim, damage, liability or
                 action resulted directly from any such acts or failures to act
                 undertaken or omitted to be taken by such Underwriter through
                 its gross negligence or willful misconduct), and shall
                 reimburse each Underwriter and each such officer, employee or
                 controlling person promptly upon demand for any legal or other
                 expenses reasonably incurred by that Underwriter, officer,
                 employee or controlling person in connection with
                 investigating or defending or preparing to defend against any
                 such loss, claim, damage, liability or action as such expenses
                 are incurred; provided, however, that the Company shall not be
                 liable in any such case to the extent that any such loss,
                 claim, damage, liability or action arises out of, or is based
                 upon, any untrue statement or alleged untrue statement or
                 omission or alleged omission made in any Preliminary
                 Prospectus, the Registration Statement or the Prospectus, or
                 in any such amendment or supplement, or in any Blue Sky
                 Application, in reliance upon and in conformity with written
                 information concerning such Underwriter furnished to the
                 Company through the Representatives by or on behalf of any
                 Underwriter specifically for inclusion therein pursuant to
                 Section 8(e) hereof; provided further, that the indemnity
                 agreement provided in this Section 8(a) with respect to any
                 Prospectus shall not inure to the benefit of any Underwriter
                 from whom the person asserting any loss, claim, damage,
                 liability or action based upon any untrue statement or alleged
                 untrue statement of material fact or omission or alleged
                 omission to state therein a material fact purchased Stock, if
                 a copy of the Prospectus in which such untrue statement or
                 alleged untrue statement or omission or alleged omission was
                 corrected has not been sent or given to such person within the
                 time required by the Securities Act and the Rules and
                 Regulations thereunder unless the failure to deliver the
                 corrected Prospectus is the result of noncompliance by the
                 Company with Section 5(c) hereof.  The foregoing indemnity
                 agreement is in addition to any liability which the Company
                 may otherwise have to any Underwriter or to any officer,
                 employee or controlling person of that Underwriter.





                                      19.
<PAGE>   20
                          (b)     Each Underwriter, severally and not jointly,
                 shall indemnify and hold harmless the Company, each of its
                 officers and employees, each of its directors, and each
                 person, if any, who controls the Company within the meaning of
                 the Securities Act, from and against any loss, claim, damage
                 or liability, joint or several, or any action in respect
                 thereof, to which the Company or any such director, officer,
                 employee or controlling person may become subject, under the
                 Securities Act or otherwise, insofar as such loss, claim,
                 damage, liability or action arises out of, or is based upon,
                 (i) any untrue statement or alleged untrue statement of a
                 material fact contained (A) in any Preliminary Prospectus, the
                 Registration Statement or the Prospectus or in any amendment
                 or supplement thereto, or (B) in any Blue Sky Application or
                 (ii) the omission or alleged omission to state in any
                 Preliminary Prospectus, the Registration Statement or the
                 Prospectus, or in any amendment or supplement thereto, or in
                 any Blue Sky Application any material fact required to be
                 stated therein or necessary to make the statements therein not
                 misleading, but in each case only to the extent that the
                 untrue statement or alleged untrue statement or omission or
                 alleged omission was made in reliance upon and in conformity
                 with written information concerning such Underwriter furnished
                 to the Company through the Representatives by or on behalf of
                 that Underwriter specifically for inclusion therein, and shall
                 reimburse the Company and any such director, officer, employee
                 or controlling person promptly upon demand for any legal or
                 other expenses reasonably incurred by the Company or any such
                 director, officer, employee or controlling person in
                 connection with investigating or defending or preparing to
                 defend against any such loss, claim, damage, liability or
                 action as such expenses are incurred.  The foregoing indemnity
                 agreement is in addition to any liability which any
                 Underwriter may otherwise have to the Company or any such
                 director, officer, employee or controlling person.

                          (c)     Promptly after receipt by an indemnified
                 party under this Section 8 of notice of any claim or the
                 commencement of any action, the indemnified party shall, if a
                 claim in respect thereof is to be made against the
                 indemnifying party under this Section 8, notify the
                 indemnifying party in writing of the claim or the commencement
                 of that action; provided, however, that the failure to notify
                 the indemnifying party shall not relieve it from any liability
                 which it may have under this Section 8 except to the extent it
                 has been materially prejudiced by such failure and, provided
                 further, that the failure to notify the indemnifying party
                 shall not relieve it from any liability which it may have to
                 an indemnified party otherwise than under this Section 8.  If
                 any such claim or action shall be brought against an
                 indemnified party, and it shall notify the indemnifying party
                 thereof, the indemnifying party shall be entitled to
                 participate therein and, to the extent that it wishes, jointly
                 with any other similarly notified indemnifying party, to
                 assume the defense thereof with counsel reasonably
                 satisfactory to the indemnified party.  After notice from the
                 indemnifying party to the indemnified party of its election to
                 assume the defense of such claim or action, the indemnifying
                 party shall not be liable to the indemnified party under this
                 Section 8 for any legal or





                                      20.
<PAGE>   21
                 other expenses subsequently incurred by the indemnified party
                 in connection with the defense thereof other than reasonable
                 costs of investigation; provided, however, that the
                 Representatives shall have the right to employ counsel to
                 represent jointly the Representatives and those other
                 Underwriters and their respective officers, employees and
                 controlling persons who may be subject to liability arising
                 out of any claim in respect of which indemnity may be sought
                 by the Underwriters against the Company under this Section 8
                 if, in the reasonable judgment of the Representatives, it is
                 advisable for the Representatives and those Underwriters,
                 officers, employees and controlling persons to be jointly
                 represented by separate counsel, and in that event the fees
                 and expenses of such separate counsel shall be paid by the
                 Company.  No indemnifying party shall (i) without the prior
                 written consent of the indemnified parties (which consent
                 shall not be unreasonably withheld), settle or compromise or
                 consent to the entry of any judgment with respect to any
                 pending or threatened claim, action, suit or proceeding in
                 respect of which indemnification or contribution may be sought
                 hereunder unless such settlement, compromise or consent
                 includes an unconditional release of each indemnified party
                 from all liability arising out of such claim, action, suit or
                 proceeding, or (ii) be liable for any settlement of any such
                 action effected without its prior written consent (which
                 consent shall not be unreasonably withheld), but if settled
                 with the consent of the indemnifying party or if there be a
                 final judgment of the plaintiff in any such action, the
                 indemnifying party agrees to indemnify and hold harmless any
                 indemnified party from and against any loss or liability by
                 reason of such settlement or judgment.

                          (d)     If the indemnification provided for in this
                 Section 8 shall for any reason be unavailable to or
                 insufficient to hold harmless an indemnified party under
                 Section 8(a) or 8(b) in respect of any loss, claim, damage or
                 liability, or any action in respect thereof, referred to
                 therein, then each indemnifying party shall, in lieu of
                 indemnifying such indemnified party, contribute to the amount
                 paid or payable by such indemnified party as a result of such
                 loss, claim, damage or liability, or action in respect
                 thereof, (i) in such proportion as shall be appropriate to
                 reflect the relative benefits received by the Company on the
                 one hand and the Underwriters on the other from the offering
                 of the Stock or (ii) if the allocation provided by clause (i)
                 above is not permitted by applicable law, in such proportion
                 as is appropriate to reflect not only the relative benefits
                 referred to in clause (i) above but also the relative fault of
                 the Company on the one hand and the Underwriters on the other
                 with respect to the statements or omissions which resulted in
                 such loss, claim, damage or liability, or action in respect
                 thereof, as well as any other relevant equitable
                 considerations.  The relative benefits received by the Company
                 on the one hand and the Underwriters on the other with respect
                 to such offering shall be deemed to be in the same proportion
                 as the total net proceeds from the offering of the Stock
                 purchased under this Agreement (before deducting expenses)
                 received by the Company, on the one hand, and the total
                 underwriting discounts and commissions received by the
                 Underwriters with respect to the shares of the Stock purchased
                 under this





                                      21.
<PAGE>   22
                 Agreement, on the other hand, bear to the total gross proceeds
                 from the offering of the shares of the Stock under this
                 Agreement, in each case as set forth in the table on the cover
                 page of the Prospectus.  The relative fault shall be
                 determined by reference to whether the untrue or alleged
                 untrue statement of a material fact or omission or alleged
                 omission to state a material fact relates to information
                 supplied by the Company or the Underwriters, the intent of the
                 parties and their relative knowledge, access to information
                 and opportunity to correct or prevent such statement or
                 omission.  The Company and the Underwriters agree that it
                 would not be just and equitable if contributions pursuant to
                 this Section 8(d) were to be determined by pro rata allocation
                 (even if the Underwriters were treated as one entity for such
                 purpose) or by any other method of allocation which does not
                 take into account the equitable considerations referred to
                 herein.  The amount paid or payable by an indemnified party as
                 a result of the loss, claim, damage or liability, or action in
                 respect thereof, referred to above in this Section 8(d) shall
                 be deemed to include, for purposes of this Section 8(d), any
                 legal or other expenses reasonably incurred by such
                 indemnified party in connection with investigating or
                 defending any such action or claim.  Notwithstanding the
                 provisions of this Section 8(d), no Underwriter shall be
                 required to contribute any amount in excess of the amount by
                 which the total price at which the Stock underwritten by it
                 and distributed to the public was offered to the public
                 exceeds the amount of any damages which such Underwriter has
                 otherwise paid or become liable to pay by reason of any untrue
                 or alleged untrue statement or omission or alleged omission.
                 No person guilty of fraudulent misrepresentation (within the
                 meaning of Section 11(f) of the Securities Act) shall be
                 entitled to contribution from any person who was not guilty of
                 such fraudulent misrepresentation.  The Underwriters'
                 obligations to contribute as provided in this Section 8(d) are
                 several in proportion to their respective underwriting
                 obligations and not joint.

                          (e)     The Representatives, on behalf of the several
                 Underwriters, severally represent and warrant to the Company
                 that (a) the statements with respect to the public offering of
                 the Stock by the Underwriters set forth on the cover page of
                 and the legend concerning over-allotments on the inside front
                 cover page of the Prospectus, (b) the information set forth in
                 the first, second and sixth paragraphs under the caption
                 "Underwriting" in the Prospectus and (c) the information with
                 respect to over-allotments and stabilization set forth in the
                 eighth paragraph and the first and second sentences of the
                 ninth paragraph under the caption "Underwriting" in the
                 Prospectus (collectively the "Underwriter Information") is
                 correct and constitutes the only information concerning such
                 Underwriters furnished in writing to the Company by or on
                 behalf of the Underwriters specifically for inclusion in the
                 Registration Statement and the Prospectus.  The Company
                 acknowledges that it has received the Underwriter Information.
                 The Representatives represent and warrant that they have been
                 authorized by each of the other Underwriters as the
                 Representatives to enter into this Agreement on its behalf and
                 to act for it in the manner herein provided.





                                      22.
<PAGE>   23
                 9.       Defaulting Underwriters. If, on either Delivery Date,
any Underwriter defaults in the performance of its obligations under this
Agreement, the remaining non-defaulting Underwriters shall be obligated to
purchase the Stock which the defaulting Underwriter agreed but failed to
purchase on such Delivery Date in the respective proportions which the number
of shares of the Firm Stock set opposite the name of each remaining
non-defaulting Underwriter in Schedule 1 hereto bears to the total number of
shares of the Firm Stock set opposite the names of all the remaining
non-defaulting Underwriters in Schedule 1 hereto; provided, however, that the
remaining non-defaulting Underwriters shall not be obligated to purchase any of
the Stock on such Delivery Date if the total number of shares of the Stock
which the defaulting Underwriter or Underwriters agreed but failed to purchase
on such date exceeds 9.09% of the total number of shares of the Stock to be
purchased on such Delivery Date, and any remaining non-defaulting Underwriter
shall not be obligated to purchase more than 110% of the number of shares of
the Stock which it agreed to purchase on such Delivery Date pursuant to the
terms of Section 2.  If the foregoing maximum is exceeded, the remaining
non-defaulting Underwriters, or those other underwriters satisfactory to the
Representatives who so agree, shall have the right, but shall not be obligated,
to purchase, in such proportion as may be agreed upon among them, all the Stock
to be purchased on such Delivery Date.  If the remaining Underwriters or other
underwriters satisfactory to the Representatives do not elect to purchase the
shares which the defaulting Underwriter or Underwriters agreed but failed to
purchase on such Delivery Date, this Agreement (or, with respect to the Second
Delivery Date, the obligation of the Underwriters to purchase, and of the
Company to sell, the Option Stock) shall terminate without liability on the
part of any non-defaulting Underwriter or the Company, except that the Company
will continue to be liable for the payment of expenses to the extent set forth
in Sections 6 and 11.  As used in this Agreement, the term "Underwriter"
includes, for all purposes of this Agreement unless the context requires
otherwise, any party not listed in Schedule 1 hereto who, pursuant to this
Section 9, purchases Firm Stock which a defaulting Underwriter agreed but
failed to purchase.

                 Nothing contained herein shall relieve a defaulting
Underwriter of any liability it may have to the Company for damages caused by
its default.  If other underwriters are obligated or agree to purchase the
Stock of a defaulting or withdrawing Underwriter, either the Representatives or
the Company may postpone the Delivery Date for up to seven full business days
in order to effect any changes that in the opinion of counsel for the Company
or counsel for the Underwriters may be necessary in the Registration Statement,
the Prospectus or in any other document or arrangement.

                 10.      Termination. The obligations of the Underwriters
hereunder may be terminated by the Representatives by notice given to and
received by the Company prior to delivery of and payment for the Firm Stock if,
prior to that time, any of the events described in Sections 7(j) or 7(k), shall
have occurred or if the Underwriters shall decline to purchase the Stock for
any reason permitted under this Agreement.

                 11.      Reimbursement of Underwriters' Expenses.  If the
Company shall fail to tender the Stock for delivery to the Underwriters by
reason of any failure, refusal or inability on the part of the Company to
perform any agreement on its part to be performed, or because





                                      23.
<PAGE>   24
any other condition of the Underwriters' obligations hereunder required to be
fulfilled by the Company is not fulfilled, the Company will reimburse the
Underwriters for all reasonable out-of-pocket expenses (including fees and
disbursements of counsel) incurred by the Underwriters in connection with this
Agreement and the proposed purchase of the Stock, and upon demand the Company
shall pay the full amount thereof to the Representatives.  If this Agreement is
terminated pursuant to Section 10 by reason of the default of one or more
Underwriters, the Company shall not be obligated to reimburse any defaulting
Underwriter on account of those expenses.

                 12.      Notices, etc.  All statements, requests, notices and
                          agreements hereunder shall be in writing, and:

                          (a)     if to the Underwriters, shall be delivered or
                 sent by mail, telex or facsimile transmission to Lehman
                 Brothers Inc., Three World Financial Center, New York, New
                 York 10285, Attention:  Syndicate Department (Fax:
                 212-526-6588), with a copy, in the case of any notice pursuant
                 to Section 11(d), to the Director of Litigation, Office of the
                 General Counsel, Lehman Brothers Inc., 3 World Financial
                 Center, 10th Floor, New York, NY 10285;

                          (b)     if to the Company, shall be delivered or sent
                 by mail, telex or facsimile transmission to the address of the
                 Company set forth in the Registration Statement, Attention:
                 Michelle Burris (Fax: 206-667-5762).

provided, however, that any notice to an Underwriter pursuant to Section 8(c)
shall be delivered or sent by mail, telex or facsimile transmission to such
Underwriter at its address set forth in its acceptance telex to the
Representatives, which address will be supplied to any other party hereto by
the Representatives upon request.  Any such statements, requests, notices or
agreements shall take effect at the time of receipt thereof.  The Company shall
be entitled to act and rely upon any request, consent, notice or agreement
given or made on behalf of the Underwriters by Lehman Brothers Inc. on behalf
of the Representatives.

                 13.      Persons Entitled to Benefit of Agreement.  This
Agreement shall inure to the benefit of and be binding upon the Underwriters,
the Company, and their respective successors.  This Agreement and the terms and
provisions hereof are for the sole benefit of only those persons, except that
(A) the representations, warranties, indemnities and agreements of the Company
contained in this Agreement shall also be deemed to be for the benefit of the
person or persons, if any, who control any Underwriter within the meaning of
Section 15 of the Securities Act and (B) the indemnity agreement of the
Underwriters contained in Section 8(b) of this Agreement shall be deemed to be
for the benefit of directors of the Company, officers and employees of the
Company and any person controlling the Company within the meaning of Section 15
of the Securities Act.  Nothing in this Agreement is intended or shall be
construed to give any person, other than the persons referred to in this
Section 16, any legal or equitable right, remedy or claim under or in respect
of this Agreement or any provision contained herein.





                                      24.
<PAGE>   25
                 14.      Survival.  The respective indemnities,
representations, warranties and agreements of the Company and the Underwriters
contained in this Agreement or made by or on behalf on them, respectively,
pursuant to this Agreement, shall survive the delivery of and payment for the
Stock and shall remain in full force and effect, regardless of any
investigation made by or on behalf of any of them or any person controlling any
of them.

                 15.      Definition of the Term "Business Day".  For purposes
of this Agreement, "business day" means any day on which the New York Stock
Exchange, Inc. is open for trading.

                 16.      Governing Law.  This Agreement shall be governed by
and construed in accordance with the laws of New York.

                 17.      Counterparts.  This Agreement may be executed in one
or more counterparts and, if executed in more than one counterpart, the
executed counterparts shall each be deemed to be an original but all such
counterparts shall together constitute one and the same instrument.

                 18.      Headings.  The headings herein are inserted for
convenience of reference only and are not intended to be part of, or to affect
the meaning or interpretation of, this Agreement.





                                      25.
<PAGE>   26
                 If the foregoing correctly sets forth the agreement between
the Company and the Underwriters, please indicate your acceptance in the space
provided for that purpose below.

                                       Very truly yours,

                                       CORIXA CORPORATION



                                       By _____________________________________
                                          Steven Gillis, Ph.D.
                                          President and Chief Executive Officer


Accepted:

LEHMAN BROTHERS INC.
INVEMED ASSOCIATES, INC.
VECTOR SECURITIES

For themselves and as Representatives
of the several Underwriters named
in Schedule 1 hereto

         By LEHMAN BROTHERS INC.

         By  _____________________________
               Authorized Representative





                                      26.
<PAGE>   27
                                   SCHEDULE 1


<TABLE>
<CAPTION>
                                                                       Number of
         Underwriters                                                   Shares  
         ------------                                                  ---------
         <S>                                                           <C>
         Lehman Brothers Inc.
         Invemed Associates, Inc.
         Vector Securities


                                                                       ---------
                 Total                                                                       
                                                                       ---------
</TABLE>





                                      27.