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                                                                 EXHIBIT 10.15



                                 IMMUSOL, INC.

                                1992 STOCK PLAN



1.       Purposes of the Plan.  The purposes of this Stock Plan are to attract
and retain the best available personnel for positions of substantial
responsibility, to provide additional incentive to Employees and Consultants of
the Company and its Subsidiaries and to promote the success of the Company's
business.  Options granted under the Plan may be incentive stock options (as
defined under Section 422 of the Code) or non-statutory stock options, as
determined by the Administrator at the time of grant of an option and subject
to the applicable provisions of Section 422 of the Code, as amended, and the
regulations promulgated thereunder.

2.       Certain Definitions.  As used herein, the following definitions shall
apply:

         (a)     "Administrator" means the Board or any of its Committees
appointed pursuant to Section 4 of the Plan.

         (b)     "Board" means the Board of Directors of the Company.

         (c)     "Code" means the Internal Revenue Code of 1986, as amended.

         (d)     "Committee" means the Committee appointed by the Board of
Directors in accordance with paragraph (a) of Section 4 of the Plan.

         (e)     "Common Stock" means the Common Stock of the Company.

         (f)     "Company" means Immusol, Inc., a California corporation.

         (g)     "Consultant" means any person, including an advisor, who is
engaged by the Company or any Parent or Subsidiary to render services and is
compensated for such services, and any director of the Company whether
compensated for such services or not provided that if and in the event the
Company registers any class of any equity security pursuant to the Exchange
Act, the term Consultant shall thereafter not include directors who are not
compensated for their services or are paid only a director's fee by the
Company.

         (h)     "Continuous Status as an Employee" means the absence of any
interruption or termination of the employment relationship by the Company or
any Subsidiary.  Continuous Status as an Employee shall not be considered
interrupted in the case of: (i) sick leave; (ii) military leave; (iii) any
other leave of absence approved by the Board, provided that such leave is for a
period of not more than ninety (90) days, unless reemployment upon the
expiration of such leave is guaranteed by contract or statute, or unless
provided otherwise pursuant to Company policy adopted from time to time; or
(iv) in the case of transfers





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between locations of the Company or between the Company, its Subsidiaries or
its successor.

         (i)     "Employee" means any person, including officers and directors,
employed by the Company or any Parent or Subsidiary of the Company.  The
payment of a director's fee by the Company shall not be sufficient to
constitute "employment" by the Company.

         (j)     "Exchange Act" means the Securities Exchange Act of 1934, as
amended.

         (k)     "Fair Market Value" means, as of any date, the value of Common
Stock determined as follows:

                      (i)         If the Common Stock is listed on any
established stock exchange or a national market system including without
limitation the National Market System of the National Association of Securities
Dealers, Inc. Automated Quotation ("NASDAQ") System, its Fair Market Value
shall be the closing sales price for such stock (or the closing bid, if no
sales were reported, as quoted on such system or exchange for the last market
trading day prior to the time of determination) as reported in the Wall Street
Journal or such other source as the Administrator deems reliable;

                      (ii)        If the Common Stock is quoted on the NASDAQ
System (but not on the National Market System thereof) or regularly quoted by a
recognized securities dealer but selling prices are not reported, its Fair
Market Value shall be the mean between the high and low asked prices for the
Common Stock or;

                    (iii)         In the absence of an established market for
the Common Stock, the Fair Market Value thereof shall be determined in good
faith by the Administrator.

         (l)     "Incentive Stock Option" means an Option intended to qualify
as an incentive stock option within the meaning of Section 422 of the Code.

         (m)     "Nonstatutory Stock Option" means an Option not intended to
qualify as an Incentive Stock Option.

         (n)     "Option" means a stock option granted pursuant to the Plan.

         (o)     "Optioned Stock" means the Common Stock subject to an Option.

         (p)     "Optionee" means an Employee or Consultant who receives an
Option.

         (q)     "Parent" means a "parent corporation", whether now or
hereafter existing, as defined in Section 424(e) of the Code.

         (r)     "Plan" means this 1992 Stock Plan.





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         (s)     "Share" means a share of the Common Stock, as adjusted in
accordance with Section 12 of the Plan.

         (t)     "Subsidiary" means a "subsidiary corporation", whether now or
hereafter existing, as defined in Section 424(f) of the Code.

3.       Stock Subject to the Plan.  Subject to the provisions of Section 12 of
the Plan, the maximum aggregate number of shares which may be optioned and sold
under the Plan is 2,300,000 shares of Common Stock.  The shares may be
authorized, but unissued, or reacquired Common Stock.

         If an Option should expire or become unexercisable for any reason
without having been exercised in full, the unpurchased Shares which were
subject thereto shall, unless the Plan shall have been terminated, become
available for future grant under the Plan.

4.       Administration of the Plan.

         (a)     Procedure.

                      (i)         Administration With Respect to Directors and
Officers.  With respect to grants of Options to Employees who are also officers
or directors of the Company, the Plan shall be administered by (A) the Board if
the Board may administer the Plan in compliance with Rule 16b-3 promulgated
under the Exchange Act or any successor thereto ("Rule 16b-3") with respect to
a plan intended to qualify thereunder as a discretionary plan, or (B) a
Committee designated by the Board to administer the Plan, which Committee shall
be constituted in such a manner as to permit the Plan to comply with Rule 16b-3
with respect to a plan intended to qualify thereunder as a discretionary plan.
Once appointed, such Committee shall continue to serve in its designated
capacity until otherwise directed by the Board.  From time to time the Board
may increase the size of the Committee and appoint additional members thereof,
remove members (with or without cause) and appoint new members in substitution
therefor, fill vacancies, however caused, and remove all members of the
Committee and thereafter directly administer the Plan, all to the extent
permitted by Rule 16b-3 with respect to a plan intended to qualify thereunder
as a discretionary plan.

                      (ii)        Multiple Administrative Bodies.  If permitted
by Rule 16b-3, the Plan may be administered by different bodies with respect to
directors, non-director officers and Employees who are neither directors nor
officers.

                    (iii)         Administration With Respect to Consultants
and Other Employees.  With respect to grants of Options to Employees or
Consultants who are neither directors nor officers of the Company, the Plan
shall be administered by (A) the Board or (B) a Committee designated by the
Board, which Committee shall be constituted in such a manner as to satisfy the
legal requirements relating to the administration of incentive stock option
plans, if any, of California corporate and securities laws and of the Code (the
"Applicable Laws").  Once appointed, such Committee shall continue to serve in
its





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designated capacity until otherwise directed by the Board.  From time to time
the Board may increase the size of the Committee and appoint additional members
thereof, remove members (with or without cause) and appoint new members in
substitution therefor, fill vacancies, however caused, and remove all members
of the Committee and thereafter directly administer the Plan, all to the extent
permitted by the Applicable Laws.

         (b)     Powers of the Administrator.  Subject to the provisions of the
Plan and in the case of a Committee, the specific duties delegated by the Board
to such Committee, the Administrator shall have the authority, in its
discretion:

                      (i)         to determine the Fair Market Value of the
Common Stock, in accordance with Section 2(k) of the Plan;

                      (ii)        to select the officers, Consultants and
Employees to whom Options may from time to time be granted hereunder;

                    (iii)         to determine whether and to what extent
Options are granted hereunder;

                      (iv)        to determine the number of shares of Common
Stock to be covered by each such award granted hereunder;

                      (v)         to approve forms of agreement for use under
the Plan;

                      (vi)        to determine the terms and conditions, not
inconsistent with the terms of the Plan, of any award granted hereunder
(including, but not limited to, the share price and any restriction or
limitation or waiver of forfeiture restrictions regarding any Option or other
award and/or the shares of Common Stock relating thereto, based in each case on
such factors as the Administrator shall determine, in its sole discretion);

                    (vii)         to determine whether and under what circum-
stances an Option may be settled in cash under subsection 9(f) instead of
Common Stock; and

         (c)     Effect of Committee's Decision.  All decisions, determinations
and interpretations of the Administrator shall be final and binding on all
Optionees and any other holders of any Options.

5.       Eligibility.

         (a)     Nonstatutory Stock Options may be granted to Employees and
Consultants.  Incentive Stock Options may be granted only to Employees.  An
Employee or Consultant who has been granted an Option may, if he is otherwise
eligible, be granted an additional Option or Options.

         (b)     Each Option shall be designated in the written option
agreement as either an Incentive Stock Option or a Nonstatutory Stock Option.
However, notwithstanding such





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designations, to the extent that the aggregate Fair Market Value of the Shares
with respect to which Options designated as Incentive Stock Options are
exercisable for the first time by any Optionee during any calendar year (under
all plans of the Company or any Parent or Subsidiary) exceeds $100,000, such
excess Options shall be treated as Nonstatutory Stock Options.

         (c)     For purposes of Section 5(b), Incentive Stock Options shall be
taken into account in the order in which they were granted, and the Fair Market
Value of the Shares shall be determined as of the time the Option with respect
to such Shares is granted.

         (d)     The Plan shall not confer upon any Optionee any right with
respect to continuation of employment or consulting relationship with the
Company, nor shall it interfere in any way with his right or the Company's
right to terminate his employment or consulting relationship at any time, with
or without cause.

6.       Term of Plan.  The Plan shall become effective upon the earlier to
occur of its adoption by the Board of Directors or its approval by the
shareholders of the Company as described in Section 18 of the Plan.  It shall
continue in effect for a term of ten (10) years unless sooner terminated under
Section 14 of the Plan.

7.       Term of Option.  The term of each Option shall be the term stated in
the Option Agreement; provided, however, that in the case of an Incentive Stock
Option, the term shall be no more than ten (10) years from the date of grant
thereof or such shorter term as may be provided in the Option Agreement.
However, in the case of an Option granted to an Optionee who, at the time the
Option is granted, owns stock representing more than ten percent (10%) of the
voting power of all classes of stock of the Company or any Parent or
Subsidiary, the term of the Option shall be five (5) years from the date of
grant thereof or such shorter term as may be provided in the Option Agreement.

8.       Option Exercise Price and Consideration.

         (a)     The per share exercise price for the Shares to be issued
pursuant to exercise of an Option shall be such price as is determined by the
Board, but shall be subject to the following:

                      (i)         In the case of an Incentive Stock Option

                                  (A)      granted to an Employee who, at the
time of the grant of such Incentive Stock Option, owns stock representing more
than ten percent (10%) of the voting power of all classes of stock of the
Company or any Parent or Subsidiary, the per Share exercise price shall be no
less than 110% of the Fair Market Value per Share on the date of grant.

                                  (B)      granted to any Employee, the per
Share exercise price shall be no less than 100% of the Fair Market Value per
Share on the date of grant.





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                      (ii)        In the case of a Nonstatutory Stock Option

                                  (A)      granted to a person who, at the time
of the grant of such Option, owns stock representing more than ten percent
(10%) of the voting power of all classes of stock of the Company or any Parent
or Subsidiary, the per Share exercise price shall be no less than 110% of the
Fair Market Value per Share on the date of the grant.

                                  (B)      granted to any person, the per Share
exercise price shall be no less than 85% of the Fair Market Value per Share on
the date of grant.

         (b)     The consideration to be paid for the Shares to be issued upon
exercise of an Option, including the method of payment, shall be determined by
the Administrator (and, in the case of an Incentive Stock Option, shall be
determined at the time of grant) and may consist entirely of (1) cash, (2)
check, (3) surrender of other shares of Common Stock of the Company which (x)
in the case of Shares acquired pursuant to the exercise of an Option, have been
owned by the Optionee for more than six (6) months on the date of surrender,
and (y) have a Fair Market Value on the date of surrender equal to the
aggregate exercise price of the Shares as to which the Option is being
exercised; or (4) delivery of a properly executed exercise notice together with
such other documentation as the Administrator and the broker, if applicable,
shall require to effect an exercise of the Option and delivery to the Company
of the sale or loan proceeds required to pay the exercise price, (5) any
combination of the foregoing methods of payment, or (6) such other
consideration and method of payment for the issuance of Shares to the extent
permitted under Applicable Laws.

9.       Exercise of Option.

         (a)     Procedure for Exercise; Rights as a Shareholder. Any Option
granted hereunder shall be exercisable at such times and under such conditions
as determined by the Board, including performance criteria with respect to the
Company and/or the Optionee, and as shall be permissible under the terms of the
Plan, but in no case at a rate of less than 20% per year over five (5) years
from the date the Option is granted.

                 An Option may not be exercised for a fraction of a Share.

                 An Option shall be deemed to be exercised when written notice
of such exercise has been given to the Company in accordance with the terms of
the Option by the person entitled to exercise the Option and full payment for
the Shares with respect to which the Option is exercised has been received by
the Company. Full payment may, as authorized by the Board, consist of any
consideration and method of payment allowable under Section 8(b) of the Plan.
Until the issuance (as evidenced by the appropriate entry on the books of the
Company or of a duly authorized transfer agent of the Company) of the stock
certificate evidencing such Shares, no right to vote or receive dividends or
any other rights as a shareholder shall exist with respect to the Optioned
Stock, notwithstanding the exercise of the Option.  The Company shall issue (or
cause to be issued) such stock certificate promptly upon exercise of the
Option.  No adjustment will be made for a





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dividend or other right for which the record date is prior to the date the
stock certificate is issued, except as provided in Section 11 of the Plan.

                 Exercise of an Option in any manner shall result in a decrease
in the number of Shares which thereafter may be available, both for purposes of
the Plan and for sale under the Option, by the number of Shares as to which the
Option is exercised.

         (b)     Termination of Employment or Consulting Relationship.  In the
event that an Optionee's Continuous Status as an Employee or Consultant
terminates (but not in the event of a change of status from Employee to
Consultant (in which case an Employee's Incentive Stock Option shall
automatically convert to a Nonstatutory Stock Option on the ninety-first (91st)
day following such change of status) or from Consultant to Employee), other
than upon the Optionee's death or disability, the Optionee may exercise his or
her Option, but only within such period of time as is determined by the
Administrator, and only to the extent that the Optionee was entitled to
exercise it at the date of termination (but in no event later than the
expiration of the term of such Option as set forth in the Notice of Grant).
If, at the date of termination, the Optionee is not entitled to exercise his or
her entire Option, the Shares covered by the unexercisable portion of the
Option shall revert to the Plan.  If, after termination, the Optionee does not
exercise his or her Option within the time specified by the Administrator, the
Option shall terminate, and the Shares covered by such Option shall revert to
the Plan.

         (c)     Disability of Optionee.  Notwithstanding the provisions of
Section 9(b) above, in the event of termination of an Optionee's consulting
relationship or Continuous Status as an Employee as a result of his or her
disability, Optionee may, but only within twelve (12) months from the date of
such termination (but in no event later than the expiration date of the term of
such Option as set forth in the Option Agreement), exercise the Option to the
extent otherwise entitled to exercise it at the date of such termination;
provided, however, that if such disability is not a "disability" as such term
is defined in Section 22(e)(3) of the Code, in the case of an Incentive Stock
Option such Incentive Stock Option shall automatically convert to a
Nonstatutory Stock Option on the day three months and one day following such
termination.  To the extent that Optionee was not entitled to exercise the
Option at the date of termination, or if Optionee does not exercise such Option
to the extent so entitled within the time specified herein, the Option shall
terminate, and the Shares covered by such Option shall revert to the Plan.

         (d)     Death of Optionee.  In the event of termination of Optionee's
Continuous Status as an Employee or Consultant as a result of death of
Optionee, the Option may be exercised at any time within twelve (12) months
following the date of death (but in no event later than the expiration date of
the term of such Option as set forth in the Option Agreement), by the
Optionee's estate or by a person who acquired the right to exercise the Option
by bequest or inheritance, but only to the extent the Optionee was entitled to
exercise the Option at the date of death.  To the extent that Optionee was not
entitled to exercise the Option at the date of termination, or if Optionee does
not exercise such Option to the extent so entitled within the time specified
herein, the Option shall terminate.





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         (e)     Rule 16b-3.  Options granted to persons subject to Section
16(b) of the Exchange Act must comply with Rule 16b-3 and shall contain such
additional conditions or restrictions as may be required thereunder to qualify
for the maximum exemption from Section 16 of the Exchange Act with respect to
Plan transactions.

         (f)     Buyout Provisions.  The Administrator may at any time offer to
buy out for a payment in cash or Shares, an Option previously granted, based on
such terms and conditions as the Administrator shall establish and communicate
to the Optionee at the time that such offer is made.

10.      Non-Transferability of Options.  This Option may not be transferred in
any manner otherwise than by will or by the laws of descent or distribution and
may be exercised during the lifetime of Optionee only by Optionee.  The terms
of this Option shall be binding upon the executors, administrators, heirs,
successors and assigns of the Optionee.

11.      Stock Withholding to Satisfy Withholding Tax Obligations. At the
discretion of the Administrator, Optionees may satisfy withholding obligations
as provided in this paragraph.  When an Optionee incurs tax liability in
connection with an Option , which tax liability is subject to tax withholding
under applicable tax laws, and the Optionee is obligated to pay the Company an
amount required to be withheld under applicable tax laws, the Optionee may
satisfy the withholding tax obligation by electing to have the Company withhold
from the Shares to be issued upon exercise of the Option that number of Shares
having a Fair Market Value equal to the amount required to be withheld.  The
Fair Market Value of the Shares to be withheld shall be determined on the date
that the amount of tax to be withheld is to be determined (the "Tax Date").

         All elections by an Optionee to have Shares withheld for this purpose
shall be made in writing in a form acceptable to the Administrator and shall be
subject to the following restrictions:

         (a)     the election must be made on or prior to the applicable Tax
Date;

         (b)     once made, the election shall be irrevocable as to the
particular Shares of the Option as to which the election is made;

         (c)     all elections shall be subject to the consent or disapproval
of the Administrator;

         (d)     if the Optionee is subject to Rule 16b-3, the election must
comply with the applicable provisions of Rule 16b-3 and shall be subject to
such additional conditions or restrictions as may be required thereunder to
qualify for the maximum exemption from Section 16 of the Exchange Act with
respect to Plan transactions.

         In the event the election to have Shares withheld is made by an
Optionee and the Tax Date is deferred under Section 83 of the Code because no
election is filed under Section 83(b) of the Code, the Optionee shall receive
the full number of Shares with respect





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to which the Option is exercised but such Optionee shall be unconditionally
obligated to tender back to the Company the proper number of Shares on the Tax
Date.

12.      Adjustments Upon Changes in Capitalization or Merger. Subject to any
required action by the shareholders of the Company, the number of shares of
Common Stock covered by each outstanding Option, and the number of shares of
Common Stock which have been authorized for issuance under the Plan but as to
which no Options have yet been granted or which have been returned to the Plan
upon cancellation or expiration of an Option, as well as the price per share of
Common Stock covered by each such outstanding Option, shall be proportionately
adjusted for any increase or decrease in the number of issued shares of Common
Stock resulting from a stock split, reverse stock split, stock dividend,
combination or reclassification of the Common Stock, or any other increase or
decrease in the number of issued shares of Common Stock effected without
receipt of consideration by the Company; provided, however, that conversion of
any convertible securities of the Company shall not be deemed to have been
"effected without receipt of consideration." Such adjustment shall be made by
the Board, whose determination in that respect shall be final, binding and
conclusive.  Except as expressly provided herein, no issuance by the Company of
shares of stock of any class, or securities convertible into shares of stock of
any class, shall affect, and no adjustment by reason thereof shall be made with
respect to, the number or price of shares of Common Stock subject to an Option.

         In the event of the proposed dissolution or liquidation of the
Company, the Board shall notify the Optionee at least fifteen (15) days prior
to such proposed action.  To the extent it has not been previously exercised,
the Option will terminate immediately prior to the consummation of such
proposed action.  In the event of a merger of the Company with or into another
corporation, the Option shall be assumed or an equivalent option shall be
substituted by such successor corporation or a parent or subsidiary of such
successor corporation.  In the event that such successor corporation does not
agree to assume the Option or to substitute an equivalent option, the Board
shall notify the Optionee that the Option shall be exercisable for a period of
fifteen (15) days from the date of such notice, and the Option will terminate
upon the expiration of such period.

13.      Time of Granting Options.  The date of grant of an Option shall, for
all purposes, be the date on which the Administrator makes the determination
granting such Option, or such other date as is determined by the Board.  Notice
of the determination shall be given to each Employee or Consultant to whom an
Option is so granted within a reasonable time after the date of such grant.

14.      Amendment and Termination of the Plan.

         (a)     Amendment and Termination.  The Board may at any time amend,
alter, suspend or discontinue the Plan, but no amendment, alteration,
suspension or discontinuation shall be made which would impair the rights  of
any Optionee under any grant theretofore made, without his or her consent.  In
addition, to the extent necessary and desirable to comply with Rule 16b-3 under
the Exchange Act or with Section 422 of the Code (or any other applicable law
or regulation, including the requirements of the NASD or





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an established stock exchange), the Company shall obtain shareholder approval
of any Plan amendment in such a manner and to such a degree as required.

         (b)     Effect of Amendment or Termination.  Any such amendment or
termination of the Plan shall not affect Options already granted and such
Options shall remain in full force and effect as if this Plan had not been
amended or terminated, unless mutually agreed otherwise between the Optionee
and the Board, which agreement must be in writing and signed by the Optionee
and the Company.

15.      Conditions Upon Issuance of Shares.  Shares shall not be issued
pursuant to the exercise of an Option unless the exercise of such Option and
the issuance and delivery of such Shares pursuant thereto shall comply with all
relevant provisions of law, including, without limitation, the Securities Act
of 1933, as amended, the Exchange Act, the rules and regulations promulgated
thereunder, and the requirements of any stock exchange upon which the Shares
may then be listed, and shall be further subject to the approval of counsel for
the Company with respect to such compliance.

         As a condition to the exercise of an Option, the Company may require
the person exercising such Option to represent and warrant at the time of any
such exercise that the Shares are being purchased only for investment and
without any present intention to sell or distribute such Shares if, in the
opinion of counsel for the Company, such a representation is required by any of
the aforementioned relevant provisions of law.

16.      Reservation of Shares.  The Company, during the term of this Plan,
will at all times reserve and keep available such number of Shares as shall be
sufficient to satisfy the requirements of the Plan.

         The inability of the Company to obtain authority from any regulatory
body having jurisdiction, which authority is deemed by the Company's counsel to
be necessary to the lawful issuance and sale of any Shares hereunder, shall
relieve the Company of any liability in respect of the failure to issue or sell
such Shares as to which such requisite authority shall not have been obtained.

17.      Agreements.  Options shall be evidenced by written agreements in such
form as the Board shall approve from time to time.

18.      Shareholder Approval.  Continuance of the Plan shall be subject to
approval by the shareholders of the Company within twelve (12) months before or
after the date the Plan is adopted. Such shareholder approval shall be obtained
in the degree and manner required under applicable state and federal law.

19.      Information to Optionees.  The Company shall provide to each Optionee,
during the period for which such Optionee has one or more Options outstanding,
a balance sheet and an income statement at least annually.





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