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                           CERTIFICATE OF DESIGNATION
                      OF RIGHTS, PREFERENCES AND PRIVILEGES
                         OF SERIES A PREFERRED STOCK OF
                               CORIXA CORPORATION
                             A DELAWARE CORPORATION


Pursuant to Section 151 and Section 103 of the General Corporation Law of the
State of Delaware, Steven Gillis and Kathleen McKereghan hereby certify that:

     (a)  They are the duly elected Chief Executive Officer and Secretary,
respectively, of Corixa Corporation, a Delaware corporation (the "Corporation").

     (b)  Pursuant to the authority conferred upon the Board of Directors of the
Corporation by the second paragraph of Article IV of the Corporation's Fifth
Amended and Restated Certificate of Incorporation (the "Certificate"), the Board
of Directors of the Corporation on March 3, 1999 adopted the following recitals
and resolutions creating a new series of preferred stock designated as Series A
Preferred Stock:

     "WHEREAS, the Certificate provides for a class of shares known as Preferred
Stock, issuable from time to time in one or more series;

     WHEREAS, the Board of Directors of the Corporation is authorized by the
Certificate to determine the powers, rights, preferences, limitations and
restrictions granted to or imposed upon any wholly unissued series of Preferred
Stock, to fix the number of shares constituting any such series, and to
determine the designation thereof, or any of them;

     WHEREAS, the Board of Directors of the Corporation desires, pursuant to its
authority as aforesaid, to determine and fix the powers, rights preferences,
limitations and restrictions relating to a series of Preferred Stock and the
number of shares constituting, and the designation of, such series;

     NOW, THEREFORE, BE IT RESOLVED, that pursuant to the authority vested in
the Board of Directors of the Corporation in accordance with the provisions of
the Certificate, a new series of Preferred Stock to be designated "Series A
Preferred Stock," is hereby created, and the Board of Directors hereby fixes and
determines the designation of, the number of shares constituting, and the
rights, preferences, privileges and restrictions relating to, such series of
Preferred Stock as follows (all terms used herein which are not otherwise
defined shall have the meanings set forth in the Certificate):

     1.   Designation. The series of Preferred Stock of the Corporation (the
"Preferred Stock") shall be designated as "Series A Preferred Stock" with a par
value of $0.001 per share.

     2.   Authorized Number. The number of shares constituting the Series A
Preferred Stock shall be Fifty Thousand (50,000) shares. The rights,
preferences, restrictions and other matters relating to the Series A Preferred
Stock set forth below are subject to the issuance of any 

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subsequent series of preferred stock. The Board of Directors is also authorized
to decrease the number of shares of any series of preferred stock prior or
subsequent to the issue of that series, but not below the number of shares of
such series then outstanding. In case the number of shares of any series shall
be so decreased, the shares constituting such decrease shall resume the status
which they had prior to the adoption of the resolution originally fixing the
number of shares of such series.

     3.   Dividend Provisions.

          (A)  Subject to the prior and superior rights of the holders of any
shares of any series of Preferred Stock which may from time to time come into
existence ranking prior and superior to the shares of Series A Preferred Stock
with respect to dividends and to the provisions of this Section 3, the holders
of the Series A Preferred Stock shall be entitled to receive, when, as, and if
declared by the Board of Directors out of funds legally available for such
purpose, dividends at the rate of $50.00 per annum per share, and no more, which
shall be cumulative, shall accrue without interest (except as otherwise provided
herein as to dividends in arrears) from the date of original issuance of such
share of Series A Preferred Stock (the "Issuance Date" with respect to such
share) and shall be payable on an annual basis in cash or in shares of Common
Stock as provided herein, on the date that is the yearly anniversary of the
Issuance Date applicable to such share of Series A Preferred Stock (each such
date being referred to herein as an "Annual Dividend Payment Date"), commencing
on the date that is the one-year anniversary of Initial Closing (as such term is
defined in the Equity Line of Credit and Securities Purchase Agreement entered
into between the Corporation and Castle Gate, L.L.C. a Washington limited
liability company, in April 1999 (the "Purchase Agreement")), to holders of
Series A Preferred Stock of record as they appear on the stock books of the
Corporation on such record dates, not more than thirty (30) days preceding the
payment dates for such dividends, as shall be fixed by the Board.

          Dividends shall begin to accrue and be cumulative on outstanding 
shares of Series A Preferred Stock from the Issuance Date with respect to such
shares. Dividends on the Series A Preferred Stock shall be paid in cash or
shares of Common Stock or any combination of cash and shares of Common Stock, at
the option of the Corporation as hereinafter provided. No dividends or other
distributions, other than dividends payable solely in shares of Common Stock,
shall be paid or set apart for payment on any shares of Common Stock, and no
purchase, redemption, or other acquisition shall be made by the Corporation of
any shares of Common Stock (other than pursuant to any stock repurchase rights
in existence prior to the date of issuance of the Series A Preferred Stock and
the repurchase of shares of Common Stock from employees, officers, directors,
consultants or other persons performing services for the Corporation or any
subsidiary pursuant to agreements under which the Corporation has the option to
repurchase such shares at cost upon the occurrence of certain events, such as
the termination of employment, or through the exercise of any right of first
refusal) unless and until all accrued and unpaid dividends (and applicable
Arrearage Interest (as defined in Section 3(C) below) on dividends in arrears)
on the Series A Preferred Stock shall have been paid or declared and set apart
for payment.

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          Any references to "distribution" contained in this Section 3 shall not
be deemed to include any stock dividend or distributions made in connection with
any liquidation, dissolution, or winding up of the Corporation, whether
voluntary or involuntary.

          (B)  If the Corporation elects in the exercise of its sole discretion
to issue shares of Common Stock in payment of dividends on the Series A
Preferred Stock with respect to any Annual Dividend Payment Date, the
Corporation shall (1) give notice to the holders of the Series A Preferred Stock
at least five days prior to the applicable Annual Dividend Payment Date of the
Corporation's election to exercise such right and (2) deliver, or cause to be
delivered, by the fifth trading day after such Annual Dividend Payment Date to
each holder of such shares the number of whole shares of Common Stock arrived at
by dividing (i) the applicable per share Conversion Price of such shares of
Common Stock (as determined in accordance with Section 6(C) below) into (ii) the
total amount of cash dividends such holder would be entitled to receive if the
aggregate dividends on the Series A Preferred Stock held by such holder which
are being paid in shares of Common Stock were being paid in cash. No fractional
shares of Common Stock shall be issued in payment of dividends. In lieu thereof,
the Corporation shall pay cash in an amount equal to the product of (x) the
applicable Conversion Price multiplied by (y) the fraction of a share of Common
Stock which would otherwise be issuable by the Corporation.

          Shares of Common Stock issued in payment of dividends on Series A
Preferred Stock pursuant to this Section shall be, and for all purposes shall be
deemed to be, validly issued, fully paid and nonassessable shares of Common
Stock; the issuance and delivery thereof is hereby authorized; and the dispatch
in full thereof will be, and for all purposes shall be deemed to be, payment in
full of the cumulative dividends to which holders are entitled on the applicable
Annual Dividend Payment Date.

          (C)  In the event the Corporation fails to elect whether to pay
dividends with respect to a particular Annual Dividend Payment Date in cash, in
shares of Common Stock, or in any combination of cash and shares of Common Stock
within thirty (30) days following such Annual Dividend Payment Date and fails to
pay such dividends within such thirty (30) day period, then such dividends will
bear Arrearage Interest, effective beginning on the applicable Annual Dividend
Payment Date, until paid. For purposes of this Section 3(C), "Arrearage
Interest" means simple interest per annum, at the then applicable rate of
interest announced by Chase Manhattan Bank, N.A. from time to time as its prime
rate, on any dividend on shares of Series A Preferred Stock which dividend is
not paid within thirty (30) days following the applicable Annual Dividend
Payment Date.

          (D)  Dividends will be paid by the Corporation on each outstanding
share of Series A Preferred Stock for a minimum of four (4) years and a maximum
of seven (7) years as provided in this Section 3(D).

               (i)  In the event any shares of Series A Preferred Stock are
converted into Common Stock pursuant to Section 6(A) or 6(B) hereof at any time
after the Issuance Date with respect to such shares pursuant to the Purchase
Agreement, the Corporation's obligation to pay dividends pursuant to this
Section 3 with respect to such shares shall terminate on the 

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effectiveness of such conversion in accordance with the terms of this
Certificate of Designation; provided, however, that notwithstanding anything to
the contrary in this Section 3(D) in no event will the Corporation's obligation
to pay dividends on such shares, whether or not such shares have been converted
into Common Stock, terminate before four (4) annual dividend payments (together
with any applicable Arrearage Interest on dividends in arrears) have been made
with respect to such shares.

               (ii) In the event (a) any shares of Series A Preferred Stock have
not been converted into shares of Common Stock pursuant to Section 6(A) or 6(B)
on or prior to the date that is the four-year anniversary of the Issuance Date
with respect to such shares (the "4 Year Anniversary" with respect to such
shares) and (b) on the earlier of the 4 Year Anniversary or any subsequent
annual anniversary of such Issuance Date the average per share closing price of
the Common Stock on the Nasdaq National Market as reported in the Wall Street
Journal (the "Closing Price") for the sixty (60) day period prior to such 4 Year
Anniversary or subsequent annual anniversary, as applicable, is greater than the
product of C x 1.20(N) (where "C" equals the Conversion Price applicable to such
shares of Series A Preferred Stock and "N" equals the number of years from the
Issuance Date with respect to such shares of Series A Preferred Stock), then the
Corporation's obligation to issue dividends pursuant to this Section 3 with
respect to such shares shall terminate effective as of such 4 Year Anniversary
or subsequent annual anniversary, as applicable, provided that the Corporation
has made at least four (4) annual dividend payments (together with any
applicable Arrearage Interest on dividends in arrears) with respect to such
shares.

               (iii) Regardless of whether any shares of Series A Preferred
Stock have been converted into shares of Common Stock in accordance with this
Certificate of Designation, the Corporation's obligation to pay dividends
pursuant to this Section 3 shall terminate fully and be no further force or
effect with respect to any shares of Series A Preferred Stock on the date that
is the seven-year anniversary of the Issuance Date with respect to such shares;
provided that the Corporation has paid all applicable accrued dividends
(together with any applicable Arrearage Interest on dividends in arrears) in
accordance with the terms of this Section 3.

     4.   Liquidation.

          (A)  Subject to the prior and superior rights of the holders of any
shares of any series of Preferred Stock which may from time to time come into
existence ranking prior and superior to the shares of Series A Preferred Stock
with respect to liquidation, in the event of any liquidation, dissolution, or
winding up of the Corporation, whether voluntary or involuntary, all of the
assets and surplus funds of the Corporation legally available for distribution
shall be distributed among the holders of Series A Preferred Stock and Common
Stock pro rata based on the number of shares of Common Stock held by each
(assuming full conversion of all such Series A Preferred Stock in accordance
with the terms of this Certificate of Designation).

          (B)  For purposes of this Section 4, a liquidation, dissolution or
winding up of the Corporation shall be deemed to occur if the Corporation shall
sell, convey, or otherwise dispose of all or substantially all of its property
or business or merge into or consolidate with any 

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other corporation (other than a wholly-owned subsidiary corporation) or effect
any other transaction or series of related transactions in which more than fifty
percent (50%) of the voting power of the Corporation is disposed of, provided
that this Section 4(b) shall not apply to a merger effected exclusively for the
purpose of changing the domicile of the Corporation; provided further that, if
such transaction or series of transactions results in the holders of the Series
A Preferred Stock receiving securities upon conversion which may then be resold
pursuant to an effective registration statement under the Securities Act of
1933, as amended (the "1933 Act"), then such transactions or series of
transactions shall not be as a liquidation, dissolution change of control or
winding up of the Corporation within the meaning of this Section 4.

          (D)  Whenever the distribution provided for in this Section 4 shall be
payable in securities or property other than cash, the value of such
distribution shall be as follows:

               (i)  Securities not subject to investment letter or other similar
restrictions on free marketability:

                    (A)  If traded on a securities exchanges or The Nasdaq Stock
Market, the value shall be deemed to be average of the closing prices of the
securities on such exchange over the 30-day period ending three (3) days prior
to the closing;

                    (B)  If actively traded over-the-counter, the value shall be
deemed to be the average of the closing bid or sale prices (whichever is
applicable) over the 30-day period ending three (3) days prior to the closing;
and

                    (C)  If there is no active public market, the value shall be
the fair market value thereof, as determined in good faith by the Board of
Directors of the Corporation.

               (ii) The method of valuation of securities subject to investment
letter or other restrictions on free marketability (other than restrictions
arising solely by virtue of a stockholder's status as an affiliate or former
affiliate) shall be to make an appropriate discount from the market value
determined in good faith by the Board of Directors of the Corporation.

     5.   Redemption. The Series A Preferred Stock shall not be redeemable.

     6.   Conversion. The holders of Series A Preferred Stock shall have
conversion rights as follows (the "Conversion Rights"):

          (A)  Optional Conversion. Subject to the limitations on conversions
contained in Section 6(E) below, each share of Series A Preferred Stock shall be
convertible, at the option of the holder thereof, at any time following the
Issuance Date thereof at the office of the Corporation or any transfer agent for
the Preferred Stock, into such number of fully paid and nonassessable shares of
Common Stock as is determined by dividing $1,000.00 by the applicable Conversion
Price for the Series A Preferred Stock (determined as provided in Section 6(C)).

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          (B)  Automatic Conversion. Each share of Series A Preferred Stock
shall automatically be converted into fully paid and nonassessable shares of
Common Stock at the applicable Conversion Price for such share of Series A
Preferred Stock on the earlier of the following: (i) in the event that on the 4
Year Anniversary or any subsequent annual anniversary of the Issuance Date for
such share the Closing Price for the sixty (60) day period prior to such 4 Year
Anniversary or subsequent annual anniversary, as applicable, is greater than the
product of C x 1.30(N) (where "C" equals the Conversion Price applicable to such
shares of Series A Preferred Stock and "N" equals the number of years from the
Issuance Date with respect to such shares of Series A Preferred Stock), and (ii)
the date that is the seven-year anniversary of the Issuance Date applicable to
the first share of Series A Preferred Stock issued pursuant to the Purchase
Agreement.

          (C)  Conversion Price. The Conversion Price applicable to a share of
Series A Preferred Stock shall be determined as follows: (i) with respect to
shares of Series A Preferred Stock issued at the Initial Closing (as defined in
the Purchase Agreement), the Conversion Price shall be equal to $8.50 per share;
and (ii) with respect to any shares of Series A Preferred Stock issued at (a)
Subsequent Closing(s) (as defined in the Purchase Agreement), if any, the
Conversion Price shall be equal to the Closing Price for the period beginning
sixty (60) days prior the date of the applicable Subsequent Closing and ending
sixty (60) days following the date of the applicable Subsequent Closing (or such
applicable shorter period of time in the event the Common Stock ceases to be
traded publicly); provided, however, with respect this subsection 6(C)(ii),
notwithstanding the immediately foregoing calculation, in no event will the
Conversion Price applicable to shares of Series A Preferred Stock issued at any
Subsequent Closing exceed the following ceiling prices (each a "Ceiling Price"):
(a) with respect to any shares of Series A Preferred Stock issued within the
first three (3) months beginning on the Execution Date (as defined in the
Purchase Agreement), the Ceiling Price shall be $9.35 per share; (b) with
respect to any shares of Series A Preferred Stock issued within the following
three (3) month period (such three (3) month period and each subsequent three
(3) month period thereafter referred to herein as a "Quarter"), the Ceiling
Price shall be $10.29 per share; (c) with respect to any shares of Series A
Preferred Stock issued within the third Quarter, the Ceiling Price shall be
$11.31 per share; (d) with respect to any shares of Series A Preferred Stock
issued within the fourth Quarter, the Ceiling Price shall be $12.45 per share;
(e) with respect to any shares of Series A Preferred Stock issued within the
fifth Quarter, the Ceiling Price shall be $13.69 per share; (f) with respect to
any shares of Series A Preferred Stock issued within the sixth Quarter, the
Ceiling Price shall be $15.06 per share; (g) with respect to any shares of
Series A Preferred Stock issued within the seventh Quarter, the Ceiling Price
shall be $16.56 per share; and (h) with respect to any shares of Series A
Preferred Stock issued within the eighth Quarter, the Ceiling Price shall be
$18.22 per share.

          (D)  Mechanics of Conversion.

               (i)  In order to effect an optional conversion pursuant to
Section 6(A) above, a holder of Series A Preferred Stock shall fax (or otherwise
deliver) a copy of the fully executed Notice of Conversion attached hereto as
Exhibit A to the Corporation and to the Corporation's transfer agent with
respect to the Common Stock. Upon receipt by the Corporation 

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of the fax copy of a Notice of Conversion from a holder, the Corporation shall
promptly send, via fax, a confirmation to such holder stating that the Notice of
Conversion has been received, the date upon which the Corporation expects to
deliver the Common Stock issuable upon such conversion and the name and
telephone number of a contact person at the Corporation regarding the
conversion. No later than two (2) business days after receipt of such
confirmation of receipt of Notice of Conversion, the holder shall surrender or
cause to be surrendered to a reputable overnight courier for next business day
delivery (two (2) business day delivery if from outside the United States) to
the Corporation, the certificates representing the shares of Series A Preferred
Stock being converted ("Preferred Stock Certificates") accompanied by duly
executed stock powers and a copy of the Notice of Conversion. The Corporation
shall, as soon as practicable thereafter, issue and deliver at such office to
such holder of the Series A Preferred Stock, or to the nominee or nominees of
such holder, a certificate or certificates for the number of shares of Common
Stock to which such holder shall be entitled as aforesaid. If such holder was a
holder of shares of Series A Preferred Stock on a record date for a dividend
payment corresponding to a particular Annual Dividend Payment Date in accordance
with Section 3(A) and such holder converts any of such shares of Series A
Preferred Stock into Common Stock on or after such Annual Dividend Payment Date,
then such holder will receive the dividend payable by the Corporation on such
shares of Series A Preferred Stock on such Annual Dividend Payment Date in
accordance with the provisions of Section 3. Upon the date of conversion stated
in the Notice of Conversion by a holder of Series A Preferred Stock, (i) the
shares covered thereby (other than the shares, if any, which cannot be issued
because their issuance would exceed the limit set forth in subsection 6(E)(i)
below) shall be deemed converted into shares of Common Stock and (ii) the
holder's rights as a holder of such converted shares of Series A Preferred Stock
shall cease and terminate, excepting only the right to receive certificates for
such shares of Common Stock and to any remedies provided herein or otherwise
available at law or in equity to such holder because of a failure by the
Corporation to comply with the terms of this Certificate of Designation.

               (ii) In the event of an automatic conversion pursuant to Section
6(B) above, the Corporation shall promptly send notification to the applicable
holders of Series A Preferred Stock stating the number of shares of Series A
Preferred Stock that have been automatically converted, the effective date of
such automatic conversion, and an explanation of events that led to such
automatic conversion. No later than two (2) business days after receipt of such
confirmation of receipt of Notice of Conversion, the holder shall surrender or
cause to be surrendered to a reputable overnight courier for next business day
delivery (two (2) business day delivery if from outside the United States) to
the Corporation, the Preferred Stock Certificates accompanied by duly executed
stock powers and a statement of the name or names in which the certificate or
certificates for shares of Common Stock are to be issued. The Corporation shall,
as soon as practicable thereafter, issue and deliver at such office to such
holder of the Series A Preferred Stock, or to the nominee or nominees of such
holder, a certificate or certificates for the number of shares of Common Stock
to which such holder shall be entitled as aforesaid. If such holder was a holder
of shares of Series A Preferred Stock on a record date for a dividend payment
corresponding to a particular Annual Dividend Payment Date in accordance with
Section 3(A) and such shares are automatically converted into shares of Common
Stock on or after such Annual Dividend Payment Date, then such holder will
receive the dividend payable by 

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the Corporation on such shares of Series A Preferred Stock on such Annual
Dividend Payment Date in accordance with the provisions of Section 3. Upon the
effective date of an automatic conversion, (i) the shares of Series A Preferred
Stock converted thereby (other than the shares, if any, which cannot be issued
because their issuance would exceed the limit set forth in subsection 6(E)(i)
below) shall be deemed converted into shares of Common Stock and (ii) the
holder's rights as a holder of such converted shares of Series A Preferred Stock
shall cease and terminate, excepting only the right to receive certificates for
such shares of Common Stock and to any remedies provided herein or otherwise
available at law or in equity to such holder because of a failure by the
Corporation to comply with the terms of this Certificate of Designation.

               (iii) Unless otherwise provided in this Certificate of
Designation, such conversion shall be deemed to have been made immediately prior
to the close of business on the date of such surrender of the Series A Preferred
Stock to be converted, and the person or persons entitled to receive the shares
of Common Stock issuable upon such conversion shall be treated for all purposes
as the record holder or holders of such shares of Common Stock as of such date.

          (E)  Limitations on Conversions. The conversion of shares of Series A
Preferred Stock shall be subject to the following limitations (each of which
limitations shall be applied independently):

               (i)  NASDAQ Rule 4460(i). So long as the Common Stock is listed
for trading on The Nasdaq National Market ("Nasdaq") or an exchange or quotation
system with a rule substantially similar to Rule 4460(i) of the Rules and
Regulations of the National Association of Securities Dealers, Inc. ("Rule
4460(i)"), then notwithstanding anything to the contrary contained in this
Certificate of Designation or the Purchase Agreement, if, at any time, the
aggregate number of shares of Common Stock then issued or issuable upon
conversion of the Series A Preferred Stock (including any shares of Common Stock
then issued or issuable upon exercise of outstanding Warrants (as such term is
defined in the Purchase Agreement), and any shares of capital stock or rights to
acquire shares of capital stock issued by the Corporation which are aggregated
or integrated with the shares of Common Stock issuable upon conversion of the
Series A Preferred Stock and the shares of Common Stock issuable upon exercise
of outstanding Warrants for purposes of such rule) equals 19.99% of the
"Outstanding Common Amount" (as hereinafter defined), the Series A Preferred
Stock shall, from that time forward, cease to be convertible into shares of
Common Stock in accordance with the terms of this Section 6, until such time as
the Corporation (i) has obtained approval of the issuance of the Common Stock
upon conversion of the Series A Preferred Stock pursuant to the Purchase
Agreement by a majority of the total votes cast on such proposal, in person or
by proxy, by the holders of the then-outstanding Common Stock (not including any
shares of Series A Preferred Stock or any shares of Common Stock held by present
or former holders of Series A Preferred Stock that were issued upon conversion
of Series A Preferred Stock) (the "Stockholder Approval"), or (ii) shall have
otherwise obtained permission to allow such issuances from Nasdaq in accordance
with Rule 4460(i). If the Common Stock is not then listed on Nasdaq or an
exchange or quotation system that has a rule substantially similar to Rule
4460(i) then the limitations set forth herein shall be inapplicable and of no
force and effect. For purposes of this subsection 6(E)(i), "Outstanding Common
Amount" means (i) the number of shares of the Common Stock 

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outstanding immediately prior to the Initial Closing (as such term is defined in
the Purchase Agreement).

               (ii) Minimum Conversion. In no event will the Corporation be
required to effect an optional conversion of any shares of Series A Preferred
Stock pursuant to Section 6(A) unless such conversion will result in the
issuance of that number of shares of Common Stock having an aggregate value of
at least $10,000,000, based upon the applicable Conversion Price for such shares
of Series A Preferred Stock, provided that if the date is more than two (2)
years after the Execution Date (as such term is defined in the Purchase
Agreement) and the aggregate value based upon the applicable Conversion Price of
all the shares of Series A Preferred Stock held by all holder(s) thereof is less
than $10,000,000, the Company will convert all, but not less than all, of such
shares of Series A Preferred Stock at the unanimous election of the holder(s)
thereof in accordance with Section 6(A).

          (F) Taxes. The Corporation shall pay any and all taxes (other than
transfer taxes or income taxes, if any, payable by the holder) which may be
imposed with respect to the issuance and delivery of the shares of Common Stock
pursuant to conversion of the Series A Preferred Stock.

          (G)  No Fractional Shares. No fractional shares of Common Stock are to
be issued upon the conversion of the Series A Preferred Stock. In lieu thereof,
the Corporation shall pay cash in an amount equal to the product of (x) the
applicable Conversion Price multiplied by (y) the fraction of a share of Common
Stock which would otherwise be issuable by the Corporation.

          (H)  Adjustments To Conversion Prices for Stock Dividends and for
Combinations or Subdivisions of Common Stock. In the event that the Corporation
at any time or from time to time after the Issuance Date of shares of Series A
Preferred Stock shall declare or pay, without consideration, any dividend on the
Common Stock payable in Common Stock or in any right to acquire Common Stock for
no consideration, or shall effect a subdivision of the outstanding shares of
Common Stock into a greater number of shares of Common Stock (by stock split,
reclassification or otherwise than by payment of a dividend in Common Stock or
in any right to acquire Common Stock), or in the event the outstanding shares of
Common Stock shall be combined or consolidated, by reclassification or
otherwise, into a lesser number of shares of Common Stock, then the applicable
Conversion Price for such shares of Series A Preferred Stock in effect
immediately prior to such event shall, concurrently with the effectiveness of
such event, be proportionately decreased or increased, as appropriate. In the
event that the Corporation shall declare or pay, without consideration, any
dividend on the Common Stock payable in any right to acquire Common Stock for no
consideration then the Corporation shall be deemed to have made a dividend
payable in Common Stock in an amount of shares equal to the maximum number of
shares issuable upon exercise of such rights to acquire Common Stock.

          (I)  Adjustments for Reclassification and Reorganization. If the
Common Stock issuable upon conversion of shares of Series A Preferred Stock
shall be changed into the 

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same or a different number of shares of any other class or classes of stock,
whether by capital reorganization, reclassification or otherwise (other than a
subdivision or combination of shares provided for in subsection 6(H) above or a
merger or other reorganization referred to in Section 4(B) above), the
applicable Conversion Price then in effect for such shares shall, concurrently
with the effectiveness of such reorganization or reclassification, be
proportionately adjusted so that the Series A Preferred Stock shall be
convertible into, in lieu of the number of shares of Common Stock which the
holders would otherwise have been entitled to receive, a number of shares of
such other class or classes of stock equivalent to the number of shares of
Common Stock that would have been subject to receipt by the holders upon
conversion of the Series A Preferred Stock immediately before that change.

          (J)  Purchase Rights. If at any time when any Series A Preferred Stock
is issued and outstanding, the Corporation issues any convertible securities or
rights to purchase stock, warrants, securities or other property (the "Purchase
Rights") pro rata to the record holders of any class of Common Stock, then the
holders of Series A Preferred Stock will be entitled to acquire, upon the terms
applicable to such Purchase Rights, the aggregate Purchase Rights which such
holder could have acquired if such holder had held the number of shares of
Common Stock acquirable upon complete conversion of the Series A Preferred Stock
(without regard to any limitations on conversion contained herein) immediately
before the date on which a record is taken for the grant, issuance or sale of
such Purchase Rights, or, if no such record is taken, the date as of which the
record holders of Common Stock are to be determined for the grant, issue or sale
of such Purchase Rights.

          (K)  No Impairment. The Corporation will not, by amendment of its
Certificate or through any reorganization, recapitalization, 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 hereunder by the Corporation, but will at
all times in good faith assist in the carrying out of all the provisions of this
Section 6 and in the taking of all such action as may be necessary or
appropriate in order to protect the Conversion Rights of the holders of the
Series A Preferred Stock against impairment.

          (L)  Certificate as to Adjustments. Upon the occurrence of each
adjustment or readjustment of the Conversion Price of the Series A Preferred
Stock pursuant to this Section 6, the Corporation, at its expense, shall
promptly compute such adjustment or readjustment in accordance with the terms
hereof and prepare and furnish to each holder of Series A Preferred Stock a
certificate setting forth such adjustment of readjustment and showing in detail
the facts upon which such adjustment or readjustment is based. The Corporation
shall, upon the written request at any time of any affected holder of Series A
Preferred Stock, furnish or cause to be furnished to such holder a like
certificate setting forth (A) such adjustment and readjustment, (B) the
Conversion Price at the time in effect, and (C) the number of shares of Common
Stock and the amount, if any, of other property which at the time would be
received upon the conversion of the Series A Preferred Stock.

          (M)  Reservation of Stock Issuable Upon Conversion. The Corporation
shall at all times reserve and keep available out of its authorized but unissued
shares of Common Stock 

                                      -10-
<PAGE>   11

solely for the purpose of effecting the conversion of the Series A Preferred
Stock such number of its shares of Common Stock as shall from time to time be
sufficient to effect the conversion of all outstanding shares of the Series A
Preferred Stock; and if at any time the number of authorized but unissued shares
of Common Stock shall not be sufficient to effect the conversion of all the then
outstanding Series A Preferred Stock, in addition to such other remedies as
shall be available to the holder of such Series A Preferred Stock, the
Corporation will take such corporate action as may, in the opinion of its
counsel, be necessary to increase its authorized but unissued shares of Common
Stock to such number of shares as shall be sufficient for such purposes.

          (N)  Notice. Any notice required by the provisions of this Section 6
to be given to the holder of Series A Preferred Stock shall be deemed given if
deposited in the United States mail, postage prepaid, and addressed to each
holder of record at his address appearing on the books of the Corporation.

     7.   Voting Rights.

          (A)  Subject to Section 7(D) below, the holder of each share of Series
A Preferred Stock shall have the right to one vote for each share of Common
Stock into which such Series A Preferred Stock could then be converted, and with
respect to such vote, such holder shall have full voting rights and powers equal
to the voting rights and powers of the holders of Common Stock, and shall be
entitled to notice of any stockholders' meeting in accordance with the bylaws of
the Corporation, and shall be entitled to vote, together with holders of Common
Stock, with respect to any question upon which holders of Common Stock have the
right to vote. Fractional votes shall not, however, be permitted and any
fractional voting rights resulting from the above formula (after aggregating all
shares into which shares of Series A Preferred Stock held by each holder could
be converted) shall be rounded to the nearest whole number (with one-half being
rounded upward). Each holder of Common Stock shall be entitled to one (1) vote
for each share of Common Stock held.

          (B)  Except as otherwise provided in Section 8 or by law, the holders
of shares of Series A Preferred Stock and the holders of shares of Common Stock
shall vote together as one class on all matters submitted to a vote of
stockholders of the Corporation.

          (C)  Except as required by law, holders of Series A Preferred Stock
shall have no special voting rights and their consent shall not be required
(except to the extent they are entitled to vote with holders of Common Stock as
set forth herein) for taking any corporate action.

          (D)  To the extent that the holders of the Series A Preferred Stock
are entitled to vote on a matter with holders of Common Stock, voting together
as one class, or as a separate class in accordance with Section 8 hereof, each
share of Series A Preferred Stock shall be entitled to a number of votes equal
to the number of shares of Common Stock into which it is then based on the
applicable Conversion Price; provided, however, (i) in the event the applicable
Conversion Price was fixed as a result of the application of the Ceiling Price
(as described in Section 6(C) hereof), then each share of Series A Preferred
Stock shall be entitled to a number of 

                                      -11-
<PAGE>   12

votes equal to the number of shares of Common Stock into which it would have
otherwise been convertible in accordance with the applicable Conversion Price in
accordance with the formula in subsection 6(C)(ii) without reference to such
Ceiling Price, and (ii) in the event the applicable Conversion Price is deemed
to be less than the greater of the applicable book or market value of a share of
Common Stock, as determined in accordance with Rule 4460(i) and Nasdaq's
interpretation thereof as applicable to the Purchase Agreement and the
transactions contemplated thereby (the "Fair Market Value" of such share of
Common Stock), then each share of Series A Preferred Stock shall be entitled to
a number of votes equal to the number of shares of Common Stock into which it
would be convertible in accordance with such Fair Market Value, without
reference to the Conversion Price or any applicable Ceiling Price.

     8.   Protective Provisions. So long as any shares of Series A Preferred
Stock are outstanding, the Corporation shall not without first obtaining the
approval by vote of the holders of at least a majority of the then outstanding
shares of Series A Preferred Stock:

          (i)  alter or change the rights, preferences or privileges of the
Series A Preferred Stock so as to affect adversely the Series A Preferred Stock;

          (ii) create any new class or series of capital stock having a
preference over the Series A Preferred Stock as to distribution of assets upon
liquidation, dissolution or winding up of the Corporation; or

          (iii) increase the authorized number of shares of Series A Preferred
Stock.

               In the event holders of at least a majority of the then
outstanding shares of Series A Preferred Stock agree to allow the Corporation to
alter or change the rights, preferences or privileges of the shares of Series A
Preferred Stock, pursuant to subsection (i) above, so as to affect the Series A
Preferred Stock, then the Corporation will deliver notice of such approved
change to the holders of the Series A Preferred Stock that did not agree to such
alteration or change (the "Dissenting Holders") and Dissenting Holders shall
have the right for a period of thirty (30) days to convert pursuant to the terms
of this Certificate of Designation as they exist prior to such alteration or
change or continue to hold their shares of Series A Preferred Stock.

     9.   Status of Converted Stock. In the event any Series A Preferred Stock
shall be converted pursuant to Section 6 hereof, the shares so converted shall
be cancelled, shall return to the status of authorized but unissued preferred
stock of no designated series, and shall not be issuable by the Corporation as
Preferred Stock.

     10.  Status as Stockholder. Upon submission of a Notice of Conversion by a
holder of Series A Preferred Stock, the shares covered thereby shall be deemed
converted into shares of Common Stock and the holder's rights as a holder of
such converted shares of Series A Preferred Stock shall cease and terminate,
excepting only the right to receive certificates for such shares of Common Stock
and to any remedies provided herein or otherwise available at law or in equity
to such holder because of a failure by the Corporation to comply with the terms
of this Certificate of Designation.

                                      -12-
<PAGE>   13

     11.  Lost or Stolen Certificates. Upon receipt by the Corporation of
evidence of the loss, theft, destruction or mutilation of any Preferred Stock
Certificates representing shares of Series A Preferred Stock, and (in the case
of loss, theft or destruction) of indemnity reasonably satisfactory to the
Corporation, and upon surrender and cancellation of the Preferred Stock
Certificate(s), if mutilated, the Corporation shall execute and deliver new
Preferred Stock Certificate(s) of like tenor and date.

                                      * * *

     RESOLVED FURTHER, that the Chief Executive Officer, the President or any
Vice President, and the Secretary, the Chief Financial Officer, the Treasurer,
or any Assistant Secretary or Assistant Treasurer of the Corporation are each
authorized to execute, verify, and file a Certificate of Designation of Rights
Preferences and Privileges in accordance with Delaware law."

                                      -13-
<PAGE>   14

     IN WITNESS WHEREOF, the undersigned have executed this certificate on April
8, 1999.



                                         ------------------------------------
                                         Steven Gillis
                                         Chairman and Chief Executive Officer


                                         ------------------------------------
                                         Kathleen McKereghan, Secretary

     The undersigned certify under penalty of perjury that they have read the
foregoing Certificate of Designation of Preferences and know the contents
thereof, and that the statements therein are true.

     Executed at Seattle, Washington, on April 8, 1999.



                                         ------------------------------------
                                         Steven Gillis
                                         Chairman and Chief Executive Officer


                                         ------------------------------------
                                         Kathleen McKereghan, Secretary
                                         ------------------------------------
                                         Steven Gillis
                                         Chairman and Chief Executive Officer


                                         ------------------------------------
                                         Kathleen McKereghan, Secretary

<PAGE>   15

                                    EXHIBIT A


                              NOTICE OF CONVERSION

     The undersigned hereby irrevocably elects to convert (the "Conversion")
________ shares of Series A Preferred Stock (the "Preferred Stock") plus all
accrued and unpaid dividends relating thereto (if any) (each defined term used
but not defined in this notice shall have the meaning assigned to it in the
Certificate of Designation, of Rights, Preferences and Privileges of Series A
Preferred Stock of Corixa Corporation (the "Certificate of Designation")), into
shares of common stock ("Common Stock") of Corixa Corporation (the "Company")
according to the conditions of the Certificate of Designation, as of the date
written below. If securities are to be issued in the name of a person other than
the undersigned, the undersigned will pay all transfer taxes payable with
respect thereto. No fee will be charged to the holder for any conversion except
as provided herein.

     The undersigned covenants that all offers and sales by the undersigned of
the securities issuable to the undersigned upon conversion of this Series A
Preferred Stock shall be made pursuant to registration of the Common Stock under
the Securities Act of 1933, as amended (the "Act"), or pursuant to an exemption
from registration under the Act.

     In the event of partial exercise, please reissue an appropriate certificate
for the principal balance which shall not have been converted.


                             Date of Conversion:
                                                --------------------------------
                             Applicable Conversion Price:
                                                         -----------------------
                             Amount of Dividends to be Converted,
                             if any:
                                     -------------------------------------------
                             Number of Shares of
                             Common Stock to be Issued:
                                                        ------------------------

                             Signature:
                                        ----------------------------------------
                             Name:
                                   ---------------------------------------------

                             Address:
                                      ------------------------------------------

cc:                       [Transfer Agent]
   -----------------------

ACKNOWLEDGED AND AGREED:

CORIXA CORPORATION

By:
    -------------------------------