Document:

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THIS WARRANT AND THE SHARES ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT BE SOLD, PLEDGED, OR
OTHERWISE TRANSFERRED WITHOUT AN EFFECTIVE REGISTRATION THEREOF UNDER SUCH ACT
OR PURSUANT TO RULE 144 OR AN OPINION OF COUNSEL REASONABLY SATISFACTORY TO THE
CORPORATION AND ITS COUNSEL, THAT SUCH REGISTRATION IS NOT REQUIRED.

                            WARRANT TO PURCHASE STOCK

<Table>
<S>                        <C>
Issuer:                    TolerRx, Inc., a Delaware corporation
Number of Shares:          65,000, subject to adjustment
Class of Stock:            Common Stock, $.001 par value per share
Exercise Price:            $0.10 per share, subject to adjustment
Issue Date:                February 23, 2001
Expiration Date:           As set forth below
</Table>

       THIS WARRANT CERTIFIES THAT, for the agreed upon value of $1.00 and
for other good and valuable consideration, this Warrant is issued to SILICON
VALLEY BANK (the "Holder") by TOLERRX, INC., a Delaware corporation (the
"Company").

       Subject to the terms and conditions hereinafter set forth, the Holder is
entitled upon surrender of this Warrant and the duly executed subscription form
annexed hereto as APPENDIX 1, at the office of the Company, 675 Massachusetts
Avenue, Cambridge, MA 02139, or such other office as the Company shall notify
the Holder of in writing, to purchase from the Company Sixty-Five Thousand
(65,000) fully paid and non-assessable shares (the "Shares") of the Company's
Common Stock, $.001 par value per share (the "Class"), at a purchase price per
Share of Ten Cents ($0.10) (the "Exercise Price"). Until such time as this
Warrant is exercised in full or expires, the Exercise Price and the number
Shares are subject to adjustment from time to time as hereinafter provided. This
Warrant may be exercised in whole or in part at any time and from time to time
until 5:00 PM, Eastern time February 23, 2011 (the "Expiration Date").

       If on the Commitment Termination Date (as defined in that certain Loan
and Security Agreement of even date herewith between the Company and the Holder
("Loan Agreement")), the total amount of the advances made to the Company
pursuant to the Loan Agreement has not exceeded Six Hundred Thousand Dollars
($600,000), then the number of Shares that this Warrant is exercisable for shall
automatically be reduced by Fifteen Thousand (15,000) shares. Accordingly, prior
to the Commitment Termination Date, the total number of Shares for which this
Warrant shall be exercisable shall equal Fifty Thousand (50,000) (subject to
adjustment in accordance with the provision of Section 2 of this Warrant upon
any adjustment that effects the number of Shares) and, shall automatically
increase to Sixty-Five Thousand (65,000) (subject to adjustment in accordance
with the provision of Section 2 of this Warrant upon any adjustment that effects
the number of Shares) in the event that the total amount of the advances made to
the Company pursuant to the Loan

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Agreement has exceeded Six Hundred Thousand Dollars ($600,000) on the Commitment
Termination Date.

ARTICLE 1. EXERCISE.

              1.1    METHOD OF EXERCISE. Holder may exercise this Warrant by
delivering a duly executed Notice of Exercise in substantially the form attached
as APPENDIX 1 to the principal office of the Company. Unless Holder is
exercising the conversion right set forth in Section 1.2, Holder shall also
deliver to the Company a check for the aggregate Exercise Price for the Shares
being purchased.

              1.2    CONVERSION RIGHT. In lieu of exercising this Warrant as
specified in Section 1.1, Holder may from time to time convert this Warrant, in
whole or in part, into a number of Shares determined by dividing (a) the
aggregate fair market value of the Shares or other securities otherwise issuable
upon exercise of this Warrant minus the aggregate Exercise Price of such Shares
by (b) the fair market value of one Share. The fair market value of the Shares
shall be determined pursuant to Section 1.4.

              1.3    INTENTIONALLY OMITTED.

              1.4    FAIR MARKET VALUE.

                     1.4.1  If shares of the Class (or shares of the Company's
stock into which shares of the Class are convertible or exchangeable) are traded
on a nationally recognized securities exchange or over the counter market, the
fair market value of a Share shall be the average closing price of a share of
the Class (or the closing price of a share of the Company's stock for which
shares of the Class are convertible or exchangeable) reported for the fourteen
(14) business days immediately before Holder delivers its Notice of Exercise to
the Company.

                     1.4.2  If shares of the Class (or shares of the Company's
stock into which shares of the Class are convertible or exchangeable) are not
traded on a nationally recognized securities exchange or over the counter
market, the Board of Directors of the Company shall determine fair market value
in its reasonable good faith judgment. The foregoing notwithstanding, if Holder
advises the Board of Directors in writing that Holder disagrees with such
determination, then the Company and Holder shall promptly agree upon a reputable
investment banking firm to undertake such valuation. If the valuation of such
investment banking firm is ten percent (10%) greater than that determined by the
Board of Directors, then all fees and expenses of such investment banking firm
shall be paid by the Company. In all other circumstances, such fees and expenses
shall be paid by Holder. The valuation determined by such investment banking
firm shall be conclusive in any event.

                                       -2-

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              1.5    DELIVERY OF CERTIFICATE AND NEW WARRANT. Promptly after
Holder exercises or converts this Warrant, the Company shall deliver to Holder
certificates for the Shares acquired and, if this Warrant has not been fully
exercised or converted and has not expired, a new Warrant representing the
Shares not so acquired.

              1.6    REPLACEMENT OF WARRANTS. On receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Warrant and, in the case of loss, theft or destruction, on delivery of an
indemnity agreement reasonably satisfactory in form and amount to the Company
or, in the case of mutilation, on surrender and cancellation of this Warrant,
the Company at its expense shall execute and deliver, in lieu of this Warrant, a
new warrant of like tenor.

              1.7    REPURCHASE ON SALE, MERGER, OR CONSOLIDATION OF THE
COMPANY.

                     1.7.1. "ACQUISITION". For the purpose of this Warrant,
"Acquisition" means any sale, transfer, exclusive license, or other disposition
of all or substantially all of the assets of the Company, or any acquisition,
reorganization, consolidation, or merger of the Company where the holders of the
Company's outstanding voting equity securities immediately prior to the
transaction beneficially own less than 50.1% of the outstanding voting equity
securities of the surviving or successor entity immediately following the
transaction.

                     1.7.2. ASSUMPTION OF WARRANT. Upon the closing of any
Acquisition the successor or surviving entity shall assume the obligations of
this Warrant, and this Warrant shall be exercisable for the same securities and
property as would be payable for the Shares issuable upon exercise of the
unexercised portion of this Warrant as if such Shares were outstanding on the
record date for the Acquisition and subsequent closing. The Exercise Price shall
be adjusted accordingly, and the Exercise Price and number and class of Shares
shall continue to be subject to adjustment from time to time in accordance with
the provisions hereof.

                     1.7.3  PURCHASE RIGHT. Notwithstanding the foregoing, upon
the closing of any Acquisition, at the election of Holder, the Company shall
purchase the unexercised portion of this Warrant for cash for an amount equal to
(a) the fair market value of any consideration that would have been received by
Holder in consideration for the Shares had Holder exercised the unexercised
portion of this Warrant immediately before the record date for determining the
shareholders entitled to participate in the proceeds of the Acquisition, less
(b) the aggregate Exercise Price of the Shares, but in no event less than zero.

ARTICLE 2. ADJUSTMENTS TO THE SHARES.

              2.1    STOCK DIVIDENDS, SPLITS, ETC. If the Company declares or
pays a dividend on the outstanding shares of the Class, payable in Common Stock
or other securities, or subdivides the outstanding Common Stock into a greater
amount of Common Stock of the outstanding shares of the Class into a greater
number of shares of the Class, or subdivides the shares of the Class in a
transaction that increases the amount of Common Stock into which such shares are
convertible, then

                                       -3-

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upon exercise of this Warrant, for each Share acquired, Holder shall receive,
without cost to Holder, the total number and kind of securities to which Holder
would have been entitled had Holder owned the Shares of record as of the date
the dividend or subdivision occurred.

              2.2    RECLASSIFICATION, EXCHANGE OR SUBSTITUTION. Upon any
reclassification, exchange, substitution, reorganization or other event that
results in a change of the number and/or class of the securities issuable upon
exercise or conversion of this Warrant, Holder shall be entitled to receive,
upon exercise or conversion of this Warrant, the number and kind of securities
and property that Holder would have received for the Shares if this Warrant had
been exercised immediately before such reclassification, exchange, substitution,
reorganization or other event. The Company or its successor shall promptly issue
to Holder a new Warrant for such new securities or other property. The new
Warrant shall provide for adjustments which shall be as nearly equivalent as may
be practicable to the adjustments provided for in this Article 2 including,
without limitation, adjustments to the Exercise Price and to the number of
securities or property issuable upon exercise of the new Warrant. The provisions
of this Section 2.2 shall similarly apply to successive reclassifications,
exchanges, substitutions, reorganizations or other events.

              2.3    ADJUSTMENTS FOR COMBINATIONS, ETC. If the outstanding
shares of the Class are combined or consolidated, by reclassification or
otherwise, into a lesser number of shares, the Exercise Price shall be
proportionately increased and the number of Shares for which this Warrant is
exercisable shall be proportionately decreased.

              2.4    NO IMPAIRMENT. The Company shall not, by amendment of the
Certificate of Incorporation (the "Certificate") or its by-laws or through a
reorganization, transfer of assets, consolidation, merger, dissolution, issue,
or sale of securities or any other voluntary action, avoid or seek to avoid the
observance or performance of any of the terms to be observed or performed under
this Warrant by the Company, but shall at all times in good faith assist in
carrying out all of the provisions of this Article 2 and in taking all such
action as may be necessary or appropriate to protect Holder's rights under this
Article against impairment.

              2.5    FRACTIONAL SHARES. No fractional Shares shall be issuable
upon exercise or conversion of the Warrant and the number of Shares to be issued
shall be rounded up to the nearest whole Share.

              2.6    CERTIFICATE AS TO ADJUSTMENTS. Upon each adjustment of the
Exercise Price, number of class of Shares or number of shares of Common Stock or
other securities for which the Shares are convertible or exchangeable, the
Company at its expense shall promptly compute such adjustment, and furnish
Holder with a certificate of its Chief Financial Officer setting forth such
adjustment and the facts upon which such adjustment is based. The Company shall,
upon written request, furnish Holder a certificate setting forth the Exercise
Price, number and class of Shares and conversion ratio in effect upon the date
thereof and the series of adjustments leading to such Exercise Price, number and
class of Shares and conversion ratio.

                                       -4-

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ARTICLE 3. REPRESENTATIONS AND COVENANTS OF THE COMPANY.

              3.1    REPRESENTATIONS AND WARRANTIES. The Company hereby
represents and warrants to the Holder as follows:

                     (a)    All Shares which may be issued upon the due exercise
of this Warrant, and all Common Stock or other securities, if any, issuable upon
due conversion of the Shares, shall, upon issuance, be duly authorized, validly
issued, fully paid and non-assessable, and free of any liens and encumbrances
except for restrictions on transfer provided for herein or under applicable
federal and state securities laws.

                     (b)    The execution and delivery by the Company of this
Warrant and the performance of all obligations of the Company hereunder,
including the issuance to Holder of the right to acquire the Shares, have been
duly authorized by all necessary corporate action on the part of the Company,
and this Warrant Agreement is not inconsistent with the Certificate and/or the
Company's by-laws, does not contravene any law or governmental rule, regulation
or order applicable to it, does not and will not contravene any provision of, or
constitute a default under, any material indenture, mortgage, contract or other
instrument to which it is a party or by which it is bound, and constitutes a
legal, valid and binding agreement of the Company, enforceable in accordance
with its terms.

                     (c)    The authorized capital stock of the Company consists
of Twenty Three Million Thirty Five Thousand (23,035,000) shares, consisting of
Fourteen Million (14,000,000) shares of Common Stock, $.001 par value per share,
and Nine Million Thirty Five Thousand (9,035,000) shares of preferred stock,
$.001 par value per share. SCHEDULE 3.1(c) sets forth all of the outstanding
shares of common stock and preferred stock and outstanding options, warrants,
convertible securities, convertible debentures, and rights to acquire, subscribe
for, and/or purchase any Common Stock, preferred stock and/or other capital
stock of the Company or any securities or debentures convertible into or
exchangeable for Common Stock, preferred stock and/or other capital stock of the
Company.

                     (d)    The Company covenants that it shall at all times
cause to be reserved and kept available out of its authorized and unissued
shares such number of shares of its Common Stock and other securities as will be
sufficient to permit the exercise in full of this Warrant.

              3.2    NOTICE OF CERTAIN EVENTS. If the Company proposes at any
time (a) to declare any dividend or distribution upon any of its capital stock,
whether in cash, property, stock, or other securities and whether or not a
regular cash dividend; (b) to offer for subscription pro rata to the holders of
any class or series of its stock any additional shares of stock of any class or
series or other rights; (c) to effect any reclassification or recapitalization
of any of its securities; or (d) to merge or consolidate with or into any other
corporation, or sell, lease, license, or convey all or substantially all of its
assets, or to liquidate, dissolve or wind up, then, in connection with each such
event, the Company shall give Holder (1) at least 20 days prior written notice
of the date on which a record will

                                       -5-

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be taken for such dividend, distribution, or subscription rights (and specifying
the date on which the holders of securities of the Company shall be entitled to
receive such dividend, distribution or rights) or for determining rights to
vote, if any, in respect of the matters referred to in (c) and (d) above; (2) in
the case of the matters referred to in (c) and (d) above at least 20 days prior
written notice of the date when the same will take place (and specifying the
date on which the holders of securities of the Company will be entitled to
exchange their securities of the Company for securities or other property
deliverable upon the occurrence of such event); and (3) in the case of the
matter referred to in (e) above, the same notice as is given to the holders of
such registration rights.

              3.3    INFORMATION RIGHTS. So long as the Holder holds this
Warrant and/or any of the Shares, the Company shall deliver to the Holder (a)
within one-hundred and twenty (120) days after the end of each fiscal year of
the Company, the annual audited financial statements of the Company certified by
independent public accountants of recognized standing and (b) such other
financial statements required under and in accordance with any loan documents
between Holder and the Company or if there are no such requirements (or if the
subject loan(s) no longer are outstanding), then within forty-five (45) days
after the end of each of the first three quarters of each fiscal year, the
Company's quarterly, unaudited financial statements.

              3.4    REGISTRATION UNDER SECURITIES ACT OF 1933, AS AMENDED. The
Shares shall have certain registration rights as set forth in that certain
Registration Rights Agreement of even date herewith between Holder and the
Company (the "Registration Rights Agreement"). The Company represents and
warrants to Holder that the Company's execution, delivery and performance of the
Registration Rights Agreement (a) has been duly authorized by all necessary
corporate action of the Company's Board of Directors and shareholders, (b) will
not violate the Certificate or the Company's by-laws, each as amended, (c) will
not violate or cause a breach or default (or an event which with the passage of
time or the giving of notice or both, would constitute a breach or default)
under any agreement, instrument, mortgage, deed of trust or other arrangement
to which the Company is a party or by which it or any of its assets is subject
or bound, and (d) does not require the approval, consent or waiver of or by any
shareholder, registration rights holder or other third party which approval,
consent or waiver has not been obtained as of the date of issuance of this
Warrant.

ARTICLE 4. MISCELLANEOUS.

              4.1    AUTOMATIC CONVERSION UPON EXPIRATION. In the event that,
upon the Expiration Date, the fair market value of one Share (or other security
issuable upon the exercise hereof) as determined in accordance with Section 1.4
above is greater than the Exercise Price in effect on such date, then this
Warrant shall automatically be deemed on and as of such date to be converted
pursuant to Section 1.2 above as to all Shares (or such other securities) for
which it shall not previously have been exercised or converted, and the Company
shall promptly deliver a certificate representing the Shares (or such other
securities) issued upon such conversion to the Holder.

                                       -6-

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              4.2    LEGENDS. This Warrant and the Shares (and the securities
issuable, directly or indirectly, upon conversion of the Shares, if any) shall
be imprinted with a legend in substantially the following form:

       THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT
       OF 1933, AS AMENDED, AND MAY NOT BE SOLD, PLEDGED OR OTHERWISE
       TRANSFERRED WITHOUT AN EFFECTIVE REGISTRATION THEREOF UNDER
       SUCH ACT OR PURSUANT TO RULE 144 OR AN OPINION OF COUNSEL
       REASONABLY SATISFACTORY TO THE CORPORATION AND ITS COUNSEL THAT
       SUCH REGISTRATION IS NOT REQUIRED.

              4.3    COMPLIANCE WITH SECURITIES LAWS ON TRANSFER. This Warrant
and the Shares (and the securities issuable, directly or indirectly, upon
conversion of the Shares, if any) may not be transferred or assigned in whole or
in part without compliance with applicable federal and state securities laws by
the transferor and the transferee (including, without limitation, the delivery
of investment representation letters and legal opinions reasonably satisfactory
to the Company, as reasonably requested by the Company). The Company shall not
require Holder to provide an opinion of counsel if the transfer is to an
affiliate of Holder or if (a) there is no material question as to the
availability of current information as referenced in Rule 144(c), (b) Holder
represents that it has complied with Rule 144(d) and (e) in reasonable detail,
(c) the selling broker represents that it has complied with Rule 144(f), and (d)
the Company is provided with a copy of Holder's notice of proposed sale.

              4.4    TRANSFER PROCEDURE. Subject to the provisions of Section
4.3, Holder may transfer all or part of this Warrant and/or the Shares issuable
upon exercise of this Warrant (or the securities issuable, directly or
indirectly, upon conversion of the Shares, if any) at any time to Silicon Valley
Bancshares or The Silicon Valley Bank Foundation, or, to any other transferee by
giving the Company notice of the portion of the Warrant being transferred
setting forth the name, address and taxpayer identification number of the
transferee and surrendering this Warrant to the Company for reissuance to the
transferee(s) (and Holder if applicable).

              4.5    NOTICES. All notices and other communications from the
Company to the Holder, or vice versa, shall be deemed delivered and effective
when given personally or sent by electronic facsimile transmission, express
overnight courier service, or mailed by first-class registered or certified
mail, postage prepaid, at such address as may have been furnished to the Company
or the Holder, as the case may be, in writing by the Company or such holder from
time to time, but in all cases, unless instructed in writing otherwise, the
Company shall deliver a copy of all notices to Holder to Silicon Valley Bank,
Treasury Department, 3003 Tasman Drive, HA-200, Santa Clara, California 95054.

                                      -7-

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              4.6    WAIVER. This Warrant and any term hereof may be changed,
waived, discharged or terminated only by an instrument in writing signed by the
party against which enforcement of such change, waiver, discharge or termination
is sought.

              4.7    ATTORNEYS FEES. In the event of any dispute between the
parties concerning the terms and provisions of this Warrant, the party
prevailing in such dispute shall be entitled to collect from the other party all
costs incurred in such dispute, including reasonable attorneys' fees.

              4.8    GOVERNING LAW. This Warrant shall be governed by and
construed in accordance with the laws of the Commonwealth of Massachusetts,
without giving effect to its principles regarding conflicts of law.

                                       "COMPANY"

ATTEST:                                TOLERRX, INC.

By:    [ILLEGIBLE]                     By:  /s/ D.J. Ringler
   ---------------------------------      ------------------------------------
Name:   [ILLEGIBLE]                    Name:    D.J. Ringler
     -------------------------------        ----------------------------------
Title:  Mgr. Marketing                 Title:   CEO
      ------------------------------         ---------------------------------

                                       -8-

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                                   APPENDIX I
                               NOTICE OF EXERCISE

       1.     The undersigned hereby elects to purchase _______shares of the
_____________stock of ______________ pursuant to Section 1.1 of the attached
Warrant, and tenders herewith payment of the Exercise Price of such shares in
full.

       1.     The undersigned hereby elects to convert the attached Warrant into
Shares in the manner specified in Section 1.2 of the attached Warrant. This
conversion is exercised with respect to ________ of shares of the
________________ Stock of __________________.

       [Strike paragraph that does not apply.]

       2.     Please issue a certificate or certificates representing said
shares in the name of the undersigned or in such other name as is specified
below:

                     --------------------------------
                            (Name)

                     -------------------------------

                     -------------------------------
                            (Address)

       3.     The undersigned represents it is acquiring the shares solely for
its own account and not as a nominee for any other party and not with a view
toward the resale or distribution thereof except in compliance with applicable
securities laws.

                                       ----------------------------------------
                                                 (Signature)

------------------
     (Date)<Page>

                                                               EXECUTION VERSION

THIS WARRANT HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED OR ANY STATE SECURITIES LAWS. NO SALE OR DISPOSITION MAY BE EFFECTED
WITHOUT (i) EFFECTIVE REGISTRATION STATEMENTS RELATED THERETO, (ii) AN OPINION
OF COUNSEL OR OTHER EVIDENCE, REASONABLY SATISFACTORY TO THE COMPANY, THAT SUCH
REGISTRATIONS ARE NOT REQUIRED, (iii) RECEIPT OF NO-ACTION LETTERS FROM THE
APPROPRIATE GOVERNMENTAL AUTHORITIES, OR (iv) OTHERWISE COMPLYING WITH THE
PROVISIONS OF SECTION 7 OF THIS WARRANT.

                                  TOLERRX, INC.

                        WARRANT TO PURCHASE 73,125 SHARES
                           OF SERIES B PREFERRED STOCK

       THIS CERTIFIES THAT, for value received, SILICON VALLEY BANK and its
assignees are entitled to subscribe for and purchase 73,125 shares of the fully
paid and nonassessable Series B Preferred Stock (as adjusted pursuant to Section
4 hereof, the "Shares") of TolerRx, Inc., a Delaware corporation (the
"Company"), at the price of $1.00 per share (such price and such other price as
shall result, from time to time, from the adjustments specified in Section 4
hereof is herein referred to as the "Warrant Price"), subject to the provisions
and upon the terms and conditions hereinafter set forth. As used herein, (a) the
term "Series Preferred" shall mean the Company's presently authorized Series B
Preferred Stock, and any stock into or for which such Series B Preferred Stock
may hereafter be converted or exchanged, and after the mandatory conversion of
the Series B Preferred Stock to Common Stock shall mean the Company's Common
Stock, (b) the term "Date of Grant" shall mean December 13, 2001, and (c) the
term "Other Warrants" shall mean any other warrants issued by the Company in
connection with the transaction with respect to which this Warrant was issued,
and any warrant issued upon transfer or partial exercise of or in lieu of this
Warrant. The term "Warrant" as used herein shall be deemed to include Other
Warrants unless the context clearly requires otherwise.

       1.     TERM. The purchase right represented by this Warrant is
exercisable, in whole or in part, at any time and from time to time from the
Date of Grant through December 13, 2011.

       2.     METHOD OF EXERCISE: PAYMENT: ISSUANCE OF NEW WARRANT. Subject to
Section 1 hereof, the purchase right represented by this Warrant may be
exercised by the holder hereof, in whole or in part and from time to time, at
the election of the holder hereof, by (a) the surrender of this Warrant (with
the notice of exercise substantially in the form attached hereto as Exhibit A-1
duly completed and executed) at the principal office of the Company and by the
payment to the Company, by certified or bank check, or by wire transfer to an
account designated by the Company (a "Wire Transfer") of an amount equal to the
then applicable Warrant Price multiplied by the number of Shares then being
purchased; (b) if in connection with a registered public

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offering of the Company's securities, the surrender of this Warrant (with the
notice of exercise form attached hereto as Exhibit A-2 duly completed and
executed) at the principal office of the Company together with notice of
arrangements reasonably satisfactory to the Company for payment to the Company
either by certified or bank check or by Wire Transfer from the proceeds of the
sale of shares to be sold by the holder in such public offering (if any) of an
amount equal to the then applicable Warrant Price per share multiplied by the
number of Shares then being purchased; or (c) exercise of the "net issuance"
right provided for in Section 10.2 hereof. The person or persons in whose
name(s) any certificate(s) representing shares of Series Preferred shall be
issuable upon exercise of this Warrant shall be deemed to have become the
holder(s) of record of, and shall be treated for all purposes as the record
holder(s) of, the shares represented thereby (and such shares shall be deemed to
have been issued) immediately prior to the close of business on the date or
dates upon which this Warrant is exercised. In the event of any exercise of the
rights represented by this Warrant, certificates for the shares of stock so
purchased shall be delivered to the holder hereof as soon as possible and in any
event within thirty (30) days after such exercise and, unless this Warrant has
been fully exercised or expired, a new Warrant representing the portion of the
Shares, if any, with respect to which this Warrant shall not then have been
exercised shall also be issued to the holder hereof as soon as possible and in
any event within such thirty-day period; provided, however, at such time as the
Company is subject to the reporting requirements of the Securities Exchange Act
of 1934, as amended, if requested by the holder of this Warrant, the Company
shall cause its transfer agent to deliver the certificate representing Shares
issued upon exercise of this Warrant to a broker or other person (as directed by
the holder exercising this Warrant) within the time period required to settle
any trade made by the holder after exercise of this Warrant.

       3.     STOCK FULLY PAID. RESERVATION OF SHARES. All Shares that may be
issued upon the exercise of the rights represented by this Warrant will, upon
issuance pursuant to the terms and conditions herein, be fully paid and
nonassessable, and free from all taxes, liens and charges with respect to the
issue thereof. During the period within which the rights represented by this
Warrant may be exercised, the Company will at all times have authorized, and
reserved for the purpose of the issue upon exercise of the purchase rights
evidenced by this Warrant, a sufficient number of shares of its Series Preferred
to provide for the exercise of the rights represented by this Warrant and a
sufficient number of shares of its Common Stock to provide for the conversion of
the Series Preferred into Common Stock.

       4.     ADJUSTMENT OF WARRANT PRICE AND NUMBER OF SHARES. The number and
kind of securities purchasable upon the exercise of this Warrant and the Warrant
Price shall be subject to adjustment from time to time upon the occurrence of
certain events, as follows:

              A.     RECLASSIFICATION OR MERGER. In case of any reclassification
       or change of securities of the class issuable upon exercise of this
       Warrant (other than a change in par value, or from par value to no par
       value, or from no par value to par value, or as a result of a subdivision
       or combination), or in case of any merger of the Company with or into
       another corporation (other than a merger with another corporation in
       which the Company

                                       -2-

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       is the acquiring and the surviving corporation and which does not result
       in any reclassification or change of outstanding securities issuable upon
       exercise of this Warrant), or in case of any sale of all or substantially
       all of the assets of the Company, the Company, or such successor or
       purchasing corporation, as the case may be, shall duly execute and
       deliver to the holder of this Warrant a new Warrant (in form and
       substance satisfactory to the holder of this Warrant), or the Company
       shall make appropriate provision without the issuance of a new Warrant,
       so that the holder of this Warrant shall have the right to receive, at a
       total exercise price not to exceed that payable upon the exercise of the
       unexercised portion of this Warrant, and in lieu of the shares of Series
       Preferred theretofore issuable upon exercise of this Warrant, (i) the
       kind and amount of shares of stock, other securities, money and property
       receivable upon such reclassification, change, merger or sale by a holder
       of the number of shares of Series Preferred then purchasable under this
       Warrant, or (ii) in the case of such a merger or sale in which the
       consideration paid consists all or in part of assets other than
       securities of the successor or purchasing corporation, at the option of
       the Holder of this Warrant, the securities of the successor or purchasing
       corporation having a value at the time of the transaction equivalent to
       the valuation of the Series Preferred at the time of the transaction. Any
       new Warrant shall provide for adjustments that shall be as nearly
       equivalent as may be practicable to the adjustments provided for in this
       Section 4. The provisions of this subparagraph (a) shall similarly apply
       to successive reclassifications, changes, mergers and transfers.

              B.     SUBDIVISION OR COMBINATION OF SHARES. If the Company at any
       time while this Warrant remains outstanding and unexpired shall subdivide
       or combine its outstanding shares of Series Preferred, the Warrant Price
       shall be proportionately decreased and the number of Shares issuable
       hereunder shall be proportionately increased in the case of a subdivision
       and the Warrant Price shall be proportionately increased and the number
       of Shares issuable hereunder shall be proportionately decreased in the
       case of a combination.

              C.     STOCK DIVIDENDS AND OTHER DISTRIBUTIONS. If the Company at
       any time while this Warrant is outstanding and unexpired shall (i) pay a
       dividend with respect to Series Preferred payable in Series Preferred,
       then the Warrant Price shall be adjusted, from and after the date of
       determination of shareholders entitled to receive such dividend or
       distribution, to that price determined by multiplying the Warrant Price
       in effect immediately prior to such date of determination by a fraction
       (A) the numerator of which shall be the total number of shares of Series
       Preferred outstanding immediately prior to such dividend or distribution,
       and (B) the denominator of which shall be the total number of shares of
       Series Preferred outstanding immediately after such dividend or
       distribution; or (ii) make any other distribution with respect to Series
       Preferred (except any distribution specifically provided for in Sections
       4(a) and 4(b)), then, in each such case, provision shall be made by the
       Company such that the holder of this Warrant shall receive upon exercise
       of this Warrant a proportionate share of any such dividend or

                                       -3-

<Page>

       distribution as though it were the holder of the Series Preferred (or
       Common Stock issuable upon conversion thereof) as of the record date
       fixed for the determination of the shareholders of the Company entitled
       to receive such dividend or distribution.

              D.     ADJUSTMENT OF NUMBER OF SHARES. Upon each adjustment in the
       Warrant Price, the number of Shares of Series Preferred purchasable
       hereunder shall be adjusted, to the nearest whole share, to the product
       obtained by multiplying the number of Shares purchasable immediately
       prior to such adjustment in the Warrant Price by a faction, the numerator
       of which shall be the Warrant Price immediately prior to such adjustment
       and the denominator of which shall be the Warrant Price immediately
       thereafter.

              E.     ANTIDILUTION RIGHTS. The other antidilution rights
       applicable to the Shares of Series Preferred purchasable hereunder are
       set forth in the Company's Certificate of Incorporation, as amended
       through the Date of Grant, a true and complete copy of which is attached
       hereto as Exhibit B (the "Charter"). Such antidilution rights shall not
       be restated, amended, modified or waived if such restatement, amendment,
       modification or waiver adversely affects the holder hereof but does not
       similarly affect the other holders of the Series B Preferred Stock
       without such holder's prior written consent. The Company shall promptly
       provide the holder hereof with any restatement, amendment, modification
       or waiver of the Charter promptly after the same has been made.

       5.     NOTICE OF ADJUSTMENTS. Whenever the Warrant Price or the number of
Shares purchasable hereunder shall be adjusted pursuant to Section 4 hereof, the
Company shall make a certificate signed by its chief financial officer setting
forth, in reasonable detail, the event requiring the adjustment, the amount of
the adjustment, the method by which such adjustment was calculated, and the
Warrant Price and the number of Shares purchasable hereunder after giving effect
to such adjustment, and shall cause copies of such certificate to be mailed
(without regard to Section 13 hereof, by first class mail, postage prepaid) to
the holder of this Warrant. In addition, whenever the conversion price or
conversion ratio of the Series Preferred shall be adjusted, the Company shall
make a certificate signed by its chief financial officer setting forth, in
reasonable detail, the event requiring the adjustment, the amount of the
adjustment, the method by which such adjustment was calculated, and the
conversion price or ratio of the Series Preferred after giving effect to such
adjustment, and shall cause copies of such certificate to be mailed (without
regard to Section 13 hereof, by first class mail, postage prepaid) to the holder
of this Warrant.

       6.     FRACTIONAL SHARES. No fractional shares of Series Preferred will
be issued in connection with any exercise hereunder, but in lieu of such
fractional shares the Company shall make a cash payment therefor based on the
fair market value of the Series Preferred on the date of exercise as reasonably
determined in good faith by the Company's Board of Directors.

                                       -4-

<Page>

       7.     COMPLIANCE WITH ACT: DISPOSITION OF WARRANT OR SHARES OF SERIES
PREFERRED.

              A.     COMPLIANCE WITH ACT. The holder of this Warrant, by
       acceptance hereof, agrees that this Warrant, and the shares of Series
       Preferred to be issued upon exercise hereof and any Common Stock issued
       upon conversion thereof are being acquired for investment and that such
       holder will not offer, sell or otherwise dispose of this Warrant, or any
       shares of Series Preferred to be issued upon exercise hereof or any
       Common Stock issued upon conversion thereof except under circumstances
       which will not result in a violation of the Securities Act of 1933, as
       amended (the "Act") or any applicable state securities laws. Upon
       exercise of this Warrant, unless the Shares being acquired are registered
       under the Act and any applicable state securities laws or an exemption
       from such registration is available, the holder hereof shall confirm in
       writing that the shares of Series Preferred so purchased (and any shares
       of Common Stock issued upon conversion thereof) are being acquired for
       investment and not with a view toward distribution or resale in violation
       of the Act and shall confirm such other matters related thereto as may be
       reasonably requested by the Company. This Warrant and all shares of
       Series Preferred issued upon exercise of this Warrant and all shares of
       Common Stock issued upon conversion thereof (unless registered under the
       Act and any applicable state securities laws) shall be stamped or
       imprinted with a legend in substantially the following form:

              "THE SECURITIES EVIDENCED HEREBY HAVE NOT BEEN
              REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED,
              OR ANY STATE SECURITIES LAWS. NO SALE OR DISPOSITION MAY
              BE EFFECTED WITHOUT (i) EFFECTIVE REGISTRATION
              STATEMENTS RELATED THERETO, (ii) AN OPINION OF COUNSEL
              OR OTHER EVIDENCE, REASONABLY SATISFACTORY TO THE
              COMPANY, THAT SUCH REGISTRATIONS ARE NOT REQUIRED, (iii)
              RECEIPT OF NO-ACTION LETTERS FROM THE APPROPRIATE
              GOVERNMENTAL AUTHORITIES, OR (iv) OTHERWISE COMPLYING
              WITH THE PROVISIONS OF SECTION 7 OF THE WARRANT UNDER
              WHICH THESE SECURITIES WERE ISSUED, DIRECTLY OR
              INDIRECTLY."

       Said legend shall be removed by the Company, upon the request of a
holder, at such time as the restrictions on the transfer of the applicable
security shall have terminated. In addition, in connection with the issuance of
this Warrant, the holder specifically represents to the Company by acceptance of
this Warrant as follows:

                            (1)    The holder is aware of the Company's business
                     affairs and financial condition, and has acquired
                     information about the Company sufficient to reach an
                     informed and knowledgeable decision to acquire this
                     Warrant. The holder is acquiring this Warrant for its own
                     account for

                                       -5-

<Page>

                     investment purposes only and not with a view to, or for the
                     resale in connection with, any "distribution" thereof in
                     violation of the Act.

                            (2)    The holder understands that this Warrant has
                     not been registered under the Act in reliance upon a
                     specific exemption therefrom, which exemption depends upon,
                     among other things, the bona fide nature of the holder's
                     investment intent as expressed herein.

                            (3)    The holder further understands that this
                     Warrant must be held indefinitely unless subsequently
                     registered under the Act and qualified under any applicable
                     state securities laws, or unless exemptions from
                     registration and qualification are otherwise available. The
                     holder is aware of the provisions of Rule 144, promulgated
                     under the Act.

                            (4)    The holder is an "accredited investor" as
                     such term is defined in Rule 501 of Regulation D
                     promulgated under the Act.

              B.     DISPOSITION OF WARRANT OR SHARES. With respect to any
       offer, sale or other disposition of this Warrant or any shares of Series
       Preferred acquired pursuant to the exercise of this Warrant prior to
       registration of such Warrant or shares, the holder hereof agrees to give
       written notice to the Company prior thereto, describing briefly the
       manner thereof, together with a written opinion of such holder's counsel,
       or other evidence, if reasonably satisfactory to the Company, to the
       effect that such offer, sale or other disposition may be effected without
       registration or qualification (under the Act as then in effect or any
       federal or state securities law then in effect) of this Warrant or such
       shares of Series Preferred or Common Stock and indicating whether or not
       under the Act certificates for this Warrant or such shares of Series
       Preferred to be sold or otherwise disposed of require any restrictive
       legend as to applicable restrictions on transferability in order to
       ensure compliance with such law. Upon receiving such written notice and
       reasonably satisfactory opinion or other evidence, the Company, as
       promptly as practicable but no later than fifteen (15) days after receipt
       of the written notice, shall notify such holder that such holder may sell
       or otherwise dispose of this Warrant or such shares of Series Preferred
       or Common Stock, all in accordance with the terms of the notice delivered
       to the Company. If a determination has been made pursuant to this Section
       7(b) that the opinion of counsel for the holder or other evidence is not
       reasonably satisfactory to the Company, the Company shall so notify the
       holder promptly with details thereof after such determination has been
       made. Notwithstanding the foregoing, this Warrant or such shares of
       Series Preferred or Common Stock may, as to such federal laws, be
       offered, sold or otherwise disposed of in accordance with Rule 144 or
       144A under the Act, provided that the Company shall have been furnished
       with such information as the Company may reasonably request to provide a
       reasonable assurance that the provisions of Rule 144 or 144A have been
       satisfied. Each certificate representing this Warrant or the shares of
       Series Preferred thus transferred (except a transfer pursuant

                                       -6-

<Page>

       to Rule 144 or 144A) shall bear a legend as to the applicable
       restrictions on transferability in order to ensure compliance with such
       laws, unless in the aforesaid opinion of counsel for the holder, such
       legend is not required in order to ensure compliance with such laws. The
       Company may issue stop transfer instructions to its transfer agent in
       connection with such restrictions.

              C.     APPLICABILITY OF RESTRICTIONS. Neither any restrictions of
       any legend described in this Warrant nor the requirements of Section 7(b)
       above shall apply to any transfer of, or grant of a security interest in,
       this Warrant (or the Series Preferred or Common Stock obtainable upon
       exercise thereof) or any part hereof (i) to a partner of the holder if
       the holder is a partnership or to a member of the holder if the holder is
       a limited liability company, (ii) to a partnership of which the holder is
       a partner or to a limited liability company of which the holder is a
       member, or (iii) to any affiliate of the holder if the holder is a
       corporation, bank or bank holding company; PROVIDED, HOWEVER, in any such
       transfer, if applicable, the transferee shall on the Company's request
       agree in writing to be bound by the terms of this Warrant as if an
       original holder hereof. Notwithstanding the foregoing, the Company agrees
       that the holder of this Warrant shall have the right to grant
       participation interests in this Warrant.

              D.     TRANSFER RESTRICTION. At all times prior to the Company's
       initial Public Offering the holder of this Warrant shall not, without the
       prior written consent of the Company, transfer this Warrant (or any part
       hereof), any shares of Series Preferred, or any securities issued or
       issuable upon conversion of the Series Preferred, to any person who
       directly competes with the Company, unless such transfer is in connection
       with an acquisition, merger, or consolidation of the Company.

       8.     RIGHTS AS SHAREHOLDERS: INFORMATION. No holder of this Warrant, as
such, shall be entitled to vote or receive dividends or be deemed the holder of
Series Preferred or any other securities of the Company which may at any time be
issuable on the exercise hereof for any purpose, nor shall anything contained
herein be construed to confer upon the holder of this Warrant, as such, any of
the rights of a shareholder of the Company or any right to vote for the election
of directors or upon any matter submitted to shareholders at any meeting
thereof, or to receive notice of meetings, or to receive dividends or
subscription rights or otherwise until this Warrant shall have been exercised
and the Shares purchasable upon the exercise hereof shall have become
deliverable, as provided herein. Notwithstanding the foregoing, the Company will
transmit to the holder of this Warrant such information, documents and reports
as are generally distributed to the holders of any class or series of the
securities of the Company concurrently with the distribution thereof to the
shareholders.

       9.     REGISTRATION UNDER SECURITIES ACT OF 1933, AS AMENDED. The Shares
shall have certain registration rights as set forth in that certain Registration
Rights Agreement of even date herewith between the holder and the Company (the
"Registration Rights Agreement"). The

                                       -7-

<Page>

Company represents and warrants to Holder that the Company's execution, delivery
and performance of the Registration Rights Agreement (a) has been duly
authorized by all necessary corporate action of the Company's Board of Directors
and shareholders, (b) will not violate the Certificate or the Company's by-laws,
each as amended, (c) will not violate or cause a breach or default (or an event
which with the passage of time or the giving of notice or both, would constitute
a breach or default) under any agreement, instrument, mortgage, deed of trust or
other arrangement to which the Company is a party or by which it or any of its
assets is subject or bound, and (d) does not require the approval, consent or
waiver of or by any shareholder, registration rights holder or other third party
which approval, consent or waiver has not been obtained as of the date of
issuance of this Warrant.

       10.    ADDITIONAL RIGHTS.

       10.1   ACQUISITION TRANSACTIONS. The Company shall provide the holder of
this Warrant with at least twenty (20) days' written notice prior to closing
thereof of the terms and conditions of any of the following transactions (to the
extent the Company has notice thereof): (i) the sale, lease, exchange,
conveyance or other disposition of all or substantially all of the Company's
property or business, or (ii) its merger into or consolidation with any other
corporation (other than a wholly-owned subsidiary of the Company), or any
transaction (including a merger or other reorganization) or series of related
transactions, in which more than 50% of the voting power of the Company is
disposed of.

       10.2   RIGHT TO CONVERT WARRANT INTO STOCK; NET ISSUANCE.

              A.     RIGHT TO CONVERT. In addition to and without limiting the
       rights of the holder under the terms of this Warrant, the holder shall
       have the right to convert this Warrant or any portion thereof (the
       "Conversion Right") into shares of Series Preferred (or Common Stock if
       the Series Preferred has been automatically converted into Common Stock)
       as provided in this Section 10.2 at any time or from time to time during
       the term of this Warrant. Upon exercise of the Conversion Right with
       respect to a particular number of shares subject to this Warrant (the
       "Converted Warrant Shares"), the Company shall deliver to the holder
       (without payment by the holder of any exercise price or any cash or other
       consideration) that number of shares of fully paid and nonassessable
       Series Preferred (or Common Stock if the Series Preferred has been
       automatically converted into Common Stock) as is determined according to
       the following formula:

       X =  B - A
           -------
              Y

       Where: X =    the number of shares of Series Preferred (or Common Stock
                     if the Series Preferred has been automatically converted to
                     Common Stock) that shall be issued to holder

                                       -8-

<Page>

              Y =    the fair market value of one share of Series Preferred
                     (or Common Stock if the Series Preferred has been
                     automatically converted to Common Stock)

              A =    the aggregate Warrant Price of the specified number of
                     Converted Warrant Shares immediately prior to the exercise
                     of the Conversion Right (I.E., the number of Converted
                     Warrant Shares MULTIPLIED BY the Warrant Price)

              B =    the aggregate fair market value of the specified number of
                     Converted Warrant Shares (I.E., the number of Converted
                     Warrant Shares MULTIPLIED BY the fair market value of one
                     Converted Warrant Share)

       No fractional shares shall be issuable upon exercise of the Conversion
Right, and, if the number of shares to be issued determined in accordance with
the foregoing formula is other than a whole number, the Company shall pay to the
holder an amount in cash equal to the fair market value of the resulting
fractional share on the Conversion Date (as hereinafter defined). For purposes
of Section 10 of this Warrant, shares issued pursuant to the Conversion Right
shall be treated as if they were issued upon the exercise of this Warrant.

              B.     METHOD OF EXERCISE. The Conversion Right may be exercised
       by the holder by the surrender of this Warrant at the principal office of
       the Company together with a written statement (which may be in the form
       of Exhibit A-1 or Exhibit A-2 hereto) specifying that the holder thereby
       intends to exercise the Conversion Right and indicating the number of
       shares subject to this Warrant which are being surrendered (referred to
       in Section 10.2(a) hereof as the Converted Warrant Shares) in exercise of
       the Conversion Right. Such conversion shall be effective upon receipt by
       the Company of this Warrant together with the aforesaid written
       statement, or on such later date as is specified therein (the "Conversion
       Date"), and, at the election of the holder hereof, may be made contingent
       upon the closing of the sale of the Company's Common Stock to the public
       in a public offering pursuant to a Registration Statement under the Act
       (a "Public Offering"). Certificates for the shares issuable upon exercise
       of the Conversion Right and, if applicable, a new warrant evidencing the
       balance of the shares remaining subject to this Warrant, shall be issued
       as of the Conversion Date and shall be delivered to the holder within
       thirty (30) days following the Conversion Date.

              C.     DETERMINATION OF FAIR MARKET VALUE. For purposes of this
       Section 10.2, "fair market value" of a share of Series Preferred (or
       Common Stock if the Series Preferred has been automatically converted
       into Common Stock) as of a particular date (the "Determination Date")
       shall mean:

                                       -9-

<Page>

                     (i)    If the Conversion Right is exercised in connection
              with and contingent upon a Public Offering, and if the Company's
              Registration Statement relating to such Public Offering
              ("Registration Statement") has been declared effective by the
              Securities and Exchange Commission, then the initial "Price to
              Public" specified in the final prospectus with respect to such
              offering.

                     (ii)   If the Conversion Right is not exercised in
              connection with and contingent upon a Public Offering, then as
              follows:

                                   (a)    If traded on a securities exchange,
                            the fair market value of the Common Stock shall be
                            deemed to be the average of the closing prices of
                            the Common Stock on such exchange over the five
                            trading days immediately prior to the Determination
                            Date, and the fair market value of the Series
                            Preferred shall be deemed to be such fair market
                            value of the Common Stock multiplied by the number
                            of shares of Common Stock into which each share of
                            Series Preferred is then convertible;

                                   (b)    If traded on the Nasdaq Stock Market
                            or other over-the-counter system, the fair market
                            value of the Common Stock shall be deemed to be the
                            average of the closing bid prices of the Common
                            Stock over the five trading days immediately prior
                            to the Determination Date, and the fair market value
                            of the Series Preferred shall be deemed to be such
                            fair market value of the Common Stock multiplied by
                            the number of shares of Common Stock into which each
                            share of Series Preferred is then convertible; and

                                   (c)    If there is no public market for the
                            Common Stock, then fair market value shall be
                            determined in good faith by the Board of Directors
                            of the Company.

       10.3   EXERCISE PRIOR TO EXPIRATION. To the extent this Warrant is not
previously exercised as to all of the Shares subject hereto, and if the fair
market value of one share of the Series Preferred is greater than the Warrant
Price then in effect, this Warrant shall be deemed automatically exercised
pursuant to Section 10.2 above (even if not surrendered) immediately before its
expiration. For purposes of such automatic exercise, the fair market value of
one share of the Series Preferred upon such expiration shall be determined
pursuant to Section 10.2(c). To the extent this Warrant or any portion thereof
is deemed automatically exercised pursuant to this Section 10.3, the Company
agrees to promptly notify the holder hereof of the number of Shares, if any, the
holder hereof is to receive by reason of such automatic exercise.

                                      -10-

<Page>

       11.    REPRESENTATIONS AND WARRANTIES. The Company represents and
warrants to the holder of this Warrant as follows:

              A.     This Warrant has been duly authorized and executed by the
       Company and is a valid and binding obligation of the Company enforceable
       in accordance with its terms, subject to laws of general application
       relating to bankruptcy, insolvency and the relief of debtors and the
       rules of law or principles at equity governing specific performance,
       injunctive relief and other equitable remedies;

              B.     The Shares have been duly authorized and reserved for
       issuance by the Company and, when issued in accordance with the terms
       hereof, will be validly issued, fully paid and non-assessable;

              C.     The rights, preferences, privileges and restrictions
       granted to or imposed upon the Series Preferred and the holders thereof
       are as set forth in the Charter, and on the Date of Grant, each share of
       the Series Preferred represented by this Warrant is convertible into one
       share of Common Stock;

              D.     The shares of Common Stock issuable upon conversion of the
       Shares have been duly authorized and reserved for issuance by the Company
       and, when issued in accordance with the terms of the Charter will be
       validly issued, fully paid and nonassessable;

              E.     The execution and delivery of this Warrant are not, and the
       issuance of the Shares upon exercise of this Warrant in accordance with
       the terms hereof will not be, inconsistent with the Company's Charter or
       by-laws, do not and will not contravene any law, governmental rule or
       regulation, judgment or order applicable to the Company, and do not and
       will not conflict with or contravene any provision of, or constitute a
       default under, any indenture, mortgage, contract or other instrument of
       which the Company is a party or by which it is bound or require the
       consent or approval of, the giving of notice to, the registration or
       filing with or the taking of any action in respect of or by, any Federal,
       state or local government authority or agency or other person, except for
       the filing of notices pursuant to federal and state securities laws,
       which filings will be effected by the time required thereby; and

              F.     There are no actions, suits, audits, investigations or
       proceedings pending or, to the knowledge of the Company, threatened
       against the Company in any court or before any governmental commission,
       board or authority which, if adversely determined, will have a material
       adverse effect on the ability of the Company to perform its obligations
       under this Warrant.

              G.     The number of shares of Common Stock of the Company
       outstanding on the date hereof, on a fully diluted basis (assuming the
       conversion of all outstanding

                                      -11-

<Page>

       convertible securities and the exercise of all outstanding options and
       warrants), does not exceed 33,965,000 shares.

              H.     The authorized capital stock of the Company consists of
       58,000,000 shares, consisting of 31,818,750 shares of Common Stock, $.001
       par value per share, and 26,181,250 shares of preferred stock, $.001 par
       value per share, 9,035,000 of which have been designated Series A
       Preferred Stock and 17,146,250 of which have been designated Series B
       Preferred Stock SCHEDULE 11(H) sets forth all of the outstanding shares
       of common stock and preferred stock and outstanding options, warrants,
       convertible securities, convertible debentures, and rights to acquire,
       subscribe for, and/or purchase any Common Stock, preferred stock and/or
       other capital stock of the Company or any securities or debentures
       convertible into or exchangeable for Common Stock, preferred stock and/or
       other capital stock of the Company.

       12.    MODIFICATION AND WAIVER. This Warrant and any provision hereof may
be changed, waived, discharged or terminated only by an instrument in writing
signed by the party against which enforcement of the same is sought.

       13.    NOTICES. Any notice, request, communication or other document
required or permitted to be given or delivered to the holder-hereof or the
Company shall be delivered, or shall be sent by certified or registered mail,
postage prepaid, to each such holder at its address as shown on the books of the
Company or to the Company at the address indicated therefor on the signature
page of this Warrant but in all cases, unless instructed in writing otherwise,
the Company shall deliver a copy of all notices to Holder to Silicon Valley
Bank, Treasury Department, 3003 Tasman Drive, HA-200, Santa Clara, California
95054.

       14.    BINDING EFFECT ON SUCCESSORS. This Warrant shall be binding upon
any corporation succeeding the Company by merger, consolidation or acquisition
of all or substantially all of the Company's assets, and all of the obligations
of the Company relating to the Series Preferred issuable upon the exercise or
conversion of this Warrant shall survive the exercise, conversion and
termination of this Warrant and all of the covenants and agreements of the
Company shall inure to the benefit of the successors and assigns of the holder
hereof.

       15.    LOST WARRANTS OR STOCK CERTIFICATES. The Company covenants to the
holder hereof that, upon receipt of evidence reasonably satisfactory to the
Company of the loss, theft, destruction or mutilation of this Warrant or any
stock certificate and, in the case of any such loss, theft or destruction, upon
receipt of an indemnity reasonably satisfactory to the Company, or in the case
of any such mutilation upon surrender and cancellation of such Warrant or stock
certificate, the Company will make and deliver a new Warrant or stock
certificate, of like tenor, in lieu of the lost, stolen, destroyed or mutilated
Warrant or stock certificate.

       16.    DESCRIPTIVE HEADINGS. The descriptive headings of the several
paragraphs of this Warrant are inserted for convenience only and do not
constitute a part of this Warrant. The

                                      -12-

<Page>

language in this Warrant shall be construed as to its fair meaning without
regard to which party drafted this Warrant.

       17.    GOVERNING LAW. This Warrant shall be construed and enforced in
accordance with, and the rights of the parties shall be governed by, the laws of
the State of Delaware.

       18.    SURVIVAL OF REPRESENTATIONS. WARRANTIES AND AGREEMENTS. All
representations and warranties of the Company and the holder hereof contained
herein shall survive the Date of Grant, the exercise or conversion of this
Warrant (or any part hereof) or the termination or expiration of rights
hereunder. All agreements of the Company and the holder hereof contained herein
shall survive indefinitely until, by their respective terms, they are no longer
operative.

       19.    REMEDIES. In case any one or more of the covenants and agreements
contained in this Warrant shall have been breached, the holders hereof (in the
case of a breach by the Company), or the Company (in the case of a breach by a
holder), may proceed to protect and enforce their or its rights either by suit
in equity and/or by action at law, including, but not limited to, an action for
damages as a result of any such breach and/or an action for specific performance
of any such covenant or agreement contained in this Warrant.

       20.    NO IMPAIRMENT OF RIGHTS. The Company will not, by amendment of its
Charter or through any other means, avoid or seek to avoid the observance or
performance of any of the terms of this Warrant, but will at all times in good
faith assist in the carrying out of all such terms and in the taking of all such
action as may be necessary or appropriate in order to protect the rights of the
holder of this Warrant against impairment.

       21.    SEVERABILITY. The invalidity or unenforceability of any provision
of this Warrant in any jurisdiction shall not affect the validity or
enforceability of such provision in any other jurisdiction, or affect any other
provision of this Warrant, which shall remain in full force and effect.

       22.    RECOVERY OF LITIGATION COSTS. If any legal action or other
proceeding is brought for the enforcement of this Warrant, or because of an
alleged dispute, breach, default, or misrepresentation in connection with any of
the provisions of this Warrant, the successful or prevailing party or parties
shall be entitled to recover reasonable attorneys' fees and other costs incurred
in that action or proceeding, in addition to any other relief to which it or
they may be entitled.

       23.    ENTIRE AGREEMENT: MODIFICATION. This Warrant constitutes the
entire agreement between the parties pertaining to the subject matter contained
in it and supersedes all prior and contemporaneous agreements, representations,
and undertakings of the parties, whether oral or written, with respect to such
subject matter.

                                      -13-

<Page>

       The Company has caused this Warrant to be duly executed and delivered as
of the pate of Grant specified above.

                                       TOLERRX, INC.

                                       By      Douglas J. Ringler
                                         ---------------------------------------

                                       Title   CEO
                                            ------------------------------------

                                       Address:

                                      -14-

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