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                                                                     EXHIBIT 4.1

                           CERTIFICATE OF DESIGNATION
                      OF RIGHTS, PREFERENCES AND PRIVILEGES
                         OF SERIES B 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 December 24, 2000 adopted the following
recitals and resolutions creating a new series of preferred stock designated as
Series B 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 B
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 B Preferred Stock" with a
par value of $0.001 per share.

        2.     Authorized Number. The number of shares constituting the Series B
Preferred Stock shall be Thirty Seven Thousand Five Hundred (37,500) shares. The
rights, preferences, restrictions and other matters relating to the Series B
Preferred Stock set forth below are subject to the issuance of any subsequent
series of preferred stock. The Board of Directors is also

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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 B Preferred
Stock with respect to dividends and to the provisions of this Section 3, the
holders of the Series B 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 B 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 B Preferred Stock (each
such date being referred to herein as an "Annual Dividend Payment Date"), to
holders of Series B 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 B Preferred Stock from the Issuance Date with respect to such
shares. Dividends on the Series B 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 B 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 B Preferred Stock shall have been paid or declared and set apart
for payment.

               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
B Preferred Stock with respect to any Annual Dividend Payment Date, the
Corporation shall (1) give notice to the holders of the

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Series B 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 B
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 B
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 B 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 B 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 B 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 Letter
Agreement dated December 21, 2000 (the "First Amendment"), amending the Equity
Line of Credit and Securities Purchase Agreement between the Corporation and
Castle Gate, L.L.C. dated April 8, 1999 (the "Purchase Agreement"), the
Corporation's obligation to pay dividends pursuant to this Section 3 with
respect to such shares shall terminate on the 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.

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                      (ii)   In the event (a) any shares of Series B 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 1.20N (where "C" equals the
Conversion Price applicable to such shares of Series B Preferred Stock and "N"
equals the number of years from the Issuance Date with respect to such shares of
Series B 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 B
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 B 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 B 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, Series B
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 B
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 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 B
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


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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.

               (C)    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 B Preferred Stock shall not be redeemable.

        6.     Conversion. The holders of Series B 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 B 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 B Preferred Stock (determined as
provided in Section 6(C)).

               (B)    Automatic Conversion. Each share of Series B 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 B
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 1.30N (where "C" equals the Conversion Price applicable to such
shares of Series B Preferred Stock and "N" equals the number of years from the
Issuance Date with respect to such shares of


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Series B Preferred Stock), and (ii) the date that is the seven-year anniversary
of the Issuance Date applicable to the first share of Series B Preferred Stock
issued pursuant to the First Amendment.

               (C)    Conversion Price. The Conversion Price applicable to a
share of Series B Preferred Stock issued on December 29, 2000 shall be the
average per share closing price of Corixa Common Stock on the Nasdaq National
Market as reported in the Wall Street Journal for the three trading days,
December 26, 2000 through December 28, 2000.

               (D)    Mechanics of Conversion.

                      (i)    In order to effect an optional conversion pursuant
to Section 6(A) above, a holder of Series B 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 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 B 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 B 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 B 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 B
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 B 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 B 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 B 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 B Preferred Stock stating the number of shares of
Series B Preferred Stock that have been automatically converted, the effective
date of such automatic conversion, and an explanation of



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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 B 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 B 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 the Corporation on
such shares of Series B 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 B 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 B 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 B 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 B 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, the First Amendment, 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 B 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, as modified by the First
Amendment), 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 B Preferred
Stock and the shares of Common Stock issuable upon exercise of outstanding
Warrants for


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purposes of such rule) equals 19.99% of the "Outstanding Common Amount" (as
hereinafter defined), the Series B 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 B
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 B Preferred
Stock or any shares of Common Stock held by present or former holders of Series
B Preferred Stock that were issued upon conversion of Series B 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 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
B 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 B 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 B 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 B 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 B Preferred Stock.

               (G)    No Fractional Shares. No fractional shares of Common Stock
are to be issued upon the conversion of the Series B 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 B 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


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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 B 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 B Preferred Stock
shall be changed into the 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 B 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 B Preferred Stock immediately before that change.

               (J)    Purchase Rights. If at any time when any Series B
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 B 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 B 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 B Preferred Stock against impairment.

               (L)    Certificate as to Adjustments. Upon the occurrence of each
adjustment or readjustment of the Conversion Price of the Series B Preferred
Stock pursuant to this Section 6, the Corporation, at its expense, shall
promptly compute such adjustment or readjustment in


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accordance with the terms hereof and prepare and furnish to each holder of
Series B 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 B 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 B 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 solely for the purpose of effecting the
conversion of the Series B 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 B 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 B Preferred Stock,
in addition to such other remedies as shall be available to the holder of such
Series B 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 B 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 B Preferred Stock shall have the right to one vote for each share of
Common Stock into which such Series B 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 B 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 B Preferred Stock, 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.

                                      -10-
<PAGE>   11
               (C)    Except as required by law, holders of Series B 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 B 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 B 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, 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 B
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.

        8.     Protective Provisions. So long as any shares of Series B
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 B Preferred Stock:

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

               (ii)   create any new class or series of capital stock having a
preference over the Series B 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 B
Preferred Stock.

               In the event holders of at least a majority of the then
outstanding shares of Series B Preferred Stock agree to allow the Corporation to
alter or change the rights, preferences or privileges of the shares of Series B
Preferred Stock, pursuant to subsection (i) above, so as to affect the Series B
Preferred Stock, then the Corporation will deliver notice of such approved
change to the holders of the Series B 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 B Preferred Stock.

        9.     Status of Converted Stock. In the event any Series B 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.

                                      -11-
<PAGE>   12
        10.    Status as Stockholder. Upon submission of a Notice of Conversion
by a holder of Series B 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 B 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.

        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 B 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."

                                      -12-
<PAGE>   13
        IN WITNESS WHEREOF, the undersigned have executed this certificate on
December 29, 2000.

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

                                  /s/ Kathleen McKereghan
                                  ------------------------------------
                                  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 December 29, 2000.

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

                                  /s/ Kathleen McKereghan
                                  ------------------------------------
                                  Kathleen McKereghan, Secretary


<PAGE>   14
                                    EXHIBIT A

                              NOTICE OF CONVERSION

        The undersigned hereby irrevocably elects to convert (the "Conversion")
________ shares of Series B 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 B
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 B
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:____________________