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                                                                   Exhibit 10.24
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                                 LEUKOSITE, INC.

                        1997 EMPLOYEE STOCK PURCHASE PLAN


       1. DEFINITIONS. As used in this 1997 Employee Stock Purchase Plan of
LeukoSite, Inc., the following terms shall have the meanings respectively
assigned to them below:

       (a) BASE COMPENSATION means annual or annualized base compensation,
exclusive of overtime, bonuses, contributions to employee benefit plans, or
other fringe benefits.

       (b) BENEFICIARY means the person designated as the Participating
Employees' beneficiary on the Participating Employee's Membership Agreement or
other form provided by the personnel department of the Company for such purpose
or, if no such beneficiary is named, the person to whom the Option is
transferred by will or under the applicable laws of descent and distribution.

       (c) BOARD means the board of directors of the Company, except that, if
and so long as the board of directors of the Company has delegated pursuant to
Section 4 its authority with respect to the Plan to the Committee, then all
references in this Plan to the Board shall refer to the Committee acting in such
capacity.

       (d) CODE means the Internal Revenue Code of 1986, as amended.

       (e) COMMITTEE means the Compensation Committee of the Board.

       (f) COMPANY means LeukoSite, Inc., a Delaware corporation.

       (g) DISABILITY means, with respect to any Participating Employee, that an
independent medical doctor (selected by the Company's health or disability
insurer) certifies that such Participating Employee has for four (4) months,
consecutive or non-consecutive, in any twelve-month period been disabled in a
manner which seriously interferes with the performance of his or her
responsibilities for the Company or applicable Related Corporation.

       (h) ELIGIBLE EMPLOYEE means a person who is eligible under the provisions
of Section 7 to receive an Option as of a particular Offering Commencement Date.

       (i) EMPLOYER means, as to any particular Offering Period, the Company and
any Related Corporation which is designated by the Board as a corporation 

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whose Eligible Employees are to receive Options as of that Offering Period's
Offering Commencement Date.

       (j) MARKET VALUE means, as of a particular date, (i) if the Stock is
listed on an exchange, the closing price of the Stock on such date on such
exchange, (ii) if the Stock is quoted through the National Association of
Securities Dealers, Inc. Automated Quotation ("NASDAQ") National Market System
or any successor thereto, the closing price of the Stock on such date and (iii)
if the Stock is quoted through NASDAQ (but not on the National Market System) or
otherwise publicly traded, the average of the closing bid and asked prices of
the Stock on such date.

       (k) MEMBERSHIP AGREEMENT means an agreement whereby a Participating
Employee authorizes an Employer to withhold payroll deductions from his or her
Base Compensation.

       (l) OFFERING COMMENCEMENT DATE means the first business day of an
Offering Period on which Options are granted to Eligible Employees.

       (m) OFFERING PERIOD means a semi-annual period, running from either
October 1 to the next following March 31 or April 1 to the next following
September 30, during which Options will be offered under the Plan pursuant to a
determination by the Board.

       (n) OFFERING TERMINATION DATE means the last business day of an Offering
Period, on which Options must, if ever, be exercised.

       (o) OPTION means an option to purchase shares of Stock granted under the
Plan.

       (p) OPTION SHARES means shares of Stock purchasable under an Option.

       (q) PARTICIPATING EMPLOYEE means an Eligible Employee to whom an Option
is granted.

       (r) PLAN means this 1997 Employee Stock Purchase Plan of the Company, as
amended from time to time.

       (s) RELATED CORPORATION means any corporation which is or during the term
of the Plan becomes a parent corporation of the Company, as defined in Section
424(e) of the Code, or a subsidiary corporation of the Company, as defined in
Section 424(f) of the Code.

       (t) RETIRES means termination of employment with the Company and all
Related Corporations at or after attaining age 65.


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       (u) STOCK means the common stock, par value $0.01 per share, of the
Company.

       2. PURPOSE OF THE PLAN. The Plan is intended to encourage ownership of
Stock by employees of the Company and any Related Corporations and to provide an
additional incentive for the employees to promote the success of the business of
the Company and any Related Corporations. It is intended that the Plan shall be
an "employee stock purchase plan" within the meaning of Section 423 of the Code.

       3. TERM OF THE PLAN. The Plan shall become effective on the date of the
closing of the Company's initial public offering of Common Stock (the "Effective
Date"). No Option shall be granted under the Plan after the date immediately
preceding the tenth anniversary of the Effective Date.

       4. ADMINISTRATION OF THE PLAN. The Plan shall be administered by the
Board. The Board shall determine semi-annually, on or before either September 15
and March 15, whether to grant options under the Plan with respect to the
Offering Period which would otherwise begin as of October 1 and April 1,
respectively. The Board shall determine which (if any) Related Corporations
shall be Employers as of each Offering Commencement Date. Either such
determination may in the discretion of the Board apply to all subsequent
Offering Periods until modified or revoked by the Board. The Board shall have
authority to interpret the Plan, to prescribe, amend and rescind rules and
regulations relating to the Plan, to determine the terms of Options granted
under the Plan, and to make all other determinations necessary or advisable for
the administration of the Plan. All determinations of the Board under the Plan
shall be final and binding as to all persons having or claiming any interest in
or arising out of the Plan. The Board may delegate all or any portion of its
authority with respect to the Plan to the Committee, and thereafter, until such
delegation is revoked by the Board, all powers under the Plan delegated to the
Committee shall be exercised by the Committee.

       5. TERMINATION AND AMENDMENT OF PLAN. The Board may terminate or amend
the Plan at any time; provided, however, that the Board may not, without
approval by the holders of a majority of the outstanding shares of Stock,
increase the maximum number of shares of Stock purchasable under the Plan or
change the description of employees or classes of employees eligible to receive
Options. Without limiting the generality of the foregoing but subject to the
foregoing proviso, the Board may amend the Plan from time to time to increase or
decrease the length of any future Offering Periods (e.g., to a nine month
period) and to make all required conforming changes to the Plan. No termination
of or amendment to the Plan may adversely affect the rights of a

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Participating Employee with respect to any Option held by the Participating
Employee as of the date of such termination or amendment without his or her
consent.

       6. SHARES OF STOCK SUBJECT TO THE PLAN. No more than an aggregate of
150,000 shares of Stock may be issued or delivered pursuant to the exercise of
Options granted under the Plan, subject to adjustments made in accordance with
Section 9.7. Shares to be delivered upon the exercise of Options may be either
shares of Stock which are authorized but unissued or shares of Stock held by the
Company in its treasury. If an Option expires or terminates for any reason
without having been exercised in full, the unpurchased shares subject to the
Option shall become available for other Options granted under the Plan. The
Company shall, at all times during which Options are outstanding, reserve and
keep available shares of Stock sufficient to satisfy such Options (or, if less,
the maximum number still available for issuance under the foregoing limit), and
shall pay all fees and expenses incurred by the Company in connection therewith.
In the event of any capital change in the outstanding Stock as contemplated by
Section 9.7, the number of shares of Stock reserved and kept available by the
Company shall be appropriately adjusted.

       7. PERSONS ELIGIBLE TO RECEIVE OPTIONS. Each employee of an Employer
shall be granted an Option on each Offering Commencement Date on which such
employee meets all of the following requirements:

       (a) The employee is customarily employed by an Employer for more than
twenty hours per week and for more than five months per calendar year and, in
the case of any Offering Period after the first Offering Period under the Plan,
has been employed by one or more of the Employers for at least one month prior
to the applicable Offering Commencement Date.

       (b) The employee will not, after grant of the Option, own Stock
possessing five percent or more of the total combined voting power or value of
all classes of stock of the Company or of any Related Corporation. For purposes
of this paragraph (b), the rules of Section 424(d) of the Code shall apply in
determining the Stock ownership of the employee, and Stock which the employee
may purchase under outstanding options shall be treated as Stock owned by the
employee.

       (c) Upon grant of the Option, the employee's rights to purchase Stock
under all employee stock purchase plans (as defined in Section 423(b) of the
Code) of the Company and its Related Corporations will not accrue at a rate
which exceeds $10,000 of fair market value of the Stock (determined as of the
grant date) for each calendar year in which such option is outstanding at any
time. The accrual of rights to purchase Stock shall be determined in accordance
with Section 423(b)(8) of the Code.


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         8. OFFERING COMMENCEMENT DATES. Options shall be granted on the first
business day of each semi-annual period, running from either October 1 to the
next following March 31 or April 1 to the next following September 30, which is
designated by the Board as an Offering Period. Following designation by the
Board of the initial Offering Period under the Plan, all succeeding semi-annual
periods described above shall be deemed Offering Periods without need of further
Board action unless and until contrary action shall have been taken by the Board
prior to the beginning of what would otherwise be an Offering Period.

       9. TERMS AND CONDITIONS OF OPTIONS.

       9.1 GENERAL. All Options granted on a particular Offering Commencement
Date shall comply with the terms and conditions set forth in Sections 9.2
through 9.11. Subject to Sections 7(c) and 9.9, each Option granted on a
particular Offering Commencement Date shall entitle the Participating Employee
to purchase that number of shares equal to the result of $10,000 (or such lesser
amount as is selected by the Board, prior to the applicable Offering
Commencement Date, and applied uniformly during such Offering Period) divided by
the Market Value of one such share on the Offering Commencement Date and then
rounded down, if necessary, to the nearest whole number.

       9.2 PURCHASE PRICE. The purchase price of Option Shares shall be 85% of
the lesser of (a) the Market Value of the shares as of the Offering Commencement
Date or (b) the Market Value of the shares as of the Offering Termination Date.

       9.3 RESTRICTIONS ON TRANSFER.

       (a) Options may not be transferred otherwise than by will or under the
laws of descent and distribution. An Option may not be exercised by anyone other
than the Participating Employee during the lifetime of the Participating
Employee.

       (b) The Optionee shall agree in the Membership Agreement to notify the
Company of any transfer of Option Shares within two years of the Offering
Commencement Date for such Option Shares. The Company shall have the right to
place a legend on all stock certificates representing Option Shares instructing
the transfer agent to notify the Company of any transfer of such Option Shares.
The Company shall also have the right to place a legend on all stock
certificates representing Option Shares setting forth or referring to the
restriction on transferability of such Option Shares.


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       9.4 EXPIRATION. Each Option shall expire at the close of business on the
Offering Termination Date or on such earlier date as may result from the
operation of Section 9.6.

       9.5 TERMINATION OF EMPLOYMENT OF OPTIONEE. If a Participating Employee
ceases for any reason (other than death or Retirement) to be continuously
employed by an Employer, whether due to voluntary severance, involuntary
severance, transfer, or disaffiliation of a Related Corporation with the
Company, his or her Option shall immediately expire, and the Participating
Employee's accumulated payroll deductions shall be returned to the Participating
Employee. For purposes of this Section 9.5, a Participating Employee shall be
deemed to be employed throughout any leave of absence for military service,
illness or other bona fide purpose which does not exceed the longer of ninety
days or the period during which the Participating Employee's reemployment rights
are guaranteed by statute (including without limitation the Veterans
Reemployment Rights Act or similar statute relating to military service) or by
contract. If the Participating Employee does not return to active employment
prior to the termination of such period, his or her employment shall be deemed
to have ended on the ninety-first day of such leave of absence (or such longer
period guaranteed by statute or by contract as provided above).

       9.6 RETIREMENT OR DEATH OF OPTIONEE. If a Participating Employee Retires
or dies, the Participating Employee or, in the case of death, his or her
Beneficiary shall be entitled to withdraw the Participating Employee's
accumulated payroll deductions, or to purchase shares on the Offering
Termination Date to the extent that the Participating Employee would be so
entitled had he or she continued to be employed by an Employer. The number of
shares purchasable shall be limited by the amount of the Participating
Employee's accumulated payroll deductions as of the date of his or her
Retirement or death. Accumulated payroll deductions shall be applied by the
Company toward the purchase of shares only if the Participating Employee or, in
the case of death, his or her Beneficiary submits to the Employer not later than
the Offering Termination Date a written request that the deductions be so
applied. Accumulated payroll deductions not withdrawn or applied to the purchase
of shares shall be delivered by the Company to the Participating Employee or
Beneficiary within a reasonable time after the Offering Termination Date.

       9.7 CAPITAL CHANGES AFFECTING THE STOCK. In the event that, between the
Offering Commencement Date and the Offering Termination Date with respect to an
Option, a stock dividend is paid or becomes payable in respect of the Stock or
there occurs a split-up or contraction in the number of shares of Stock, the
number of shares for which the Option may thereafter be exercised and the price
to be paid for each such share shall be proportionately adjusted. In the event
that, after the Offering Commencement Date, there occurs a 

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reclassification or change of outstanding shares of Stock or a consolidation or
merger of the Company with or into another corporation or a sale or conveyance,
substantially as a whole, of the property of the Company, the Participating
Employee shall be entitled on the Offering Termination Date to receive shares of
Stock or other securities equivalent in kind and value to the shares of Stock he
or she would have held if he or she had exercised the Option in full immediately
prior to such reclassification, change, consolidation, merger, sale or
conveyance and had continued to hold such shares (together with all other shares
and securities thereafter issued in respect thereof) until the Offering
Termination Date. In the event that there is to occur a recapitalization
involving an increase in the par value of the Stock which would result in a par
value exceeding the exercise price under an outstanding Option, the Company
shall notify the Participating Employee of such proposed recapitalization
immediately upon its being recommended by the Board to the Company's
shareholders, after which the Participating Employee shall have the right to
exercise his or her Option prior to such recapitalization; if the Participating
Employee fails to exercise the Option prior to recapitalization, the exercise
price under the Option shall be appropriately adjusted. In the event that, after
the Offering Commencement Date, there occurs a dissolution or liquidation of the
Company, except pursuant to a transaction to which Section 424(a) of the Code
applies, each Option shall terminate, but the Participating Employee shall have
the right to exercise his or her Option prior to such dissolution or
liquidation.

       9.8 PAYROLL DEDUCTIONS. A Participating Employee may purchase shares
under his or her Option during any particular Offering Period by completing and
returning to the Company's personnel department at least ten days prior to the
beginning of such Offering Period a Membership Agreement indicating a percentage
(which shall be a full integer between one and eight) of his or her Base
Compensation which is to be withheld each pay period. Unless the Board decides
otherwise prior to the commencement of an Offering Period, all Participating
Employees shall be permitted, no more often than once per Offering Period, to
change the percentage of Base Compensation withheld during an Offering Period by
submitting an amended Membership Agreement to the Company's personnel department
indicating a different percentage of Base Compensation to be withheld. Any such
amended Membership Agreement shall become effective at the time determined
pursuant to rules adopted by the Board from time to time. In addition, no more
than once per Offering Period, the Participating Employee may cancel his or her
Agreement and withdraw all, but not less than all, of his or her accumulated
payroll deductions by submitting a written request therefor to the Company's
personnel department no later than the close of business on the last business
day of the Offering Period. The percentage of Base Compensation withheld may
also be changed from one Offering Period to another.


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       9.9 EXERCISE OF OPTIONS. On the Offering Termination Date the
Participating Employee may purchase the number of shares purchasable by his or
her accumulated payroll deductions, or, if less, the maximum number of shares
subject to the Option as provided in Section 9.1, provided that:

       (a) If the total number of shares which all Optionees elect to purchase,
together with any shares already purchased under the Plan, exceeds the total
number of shares which may be purchased under the Plan pursuant to Section 6,
the number of shares which each Optionee is permitted to purchase shall be
decreased PRO RATA based on the Participating Employee's accumulated payroll
deductions in relation to all accumulated payroll deductions otherwise to be
applied to the purchase of shares as of that Offering Termination Date.

       (b) If the number of shares purchasable includes a fraction, such number
shall be adjusted to the next smaller whole number and the purchase price shall
be adjusted accordingly.

       Accumulated payroll deductions not withdrawn prior to the Offering
Termination Date shall be automatically applied by the Company toward the
purchase of Option Shares or, to the extent in excess of the aggregate purchase
price of the shares then purchasable by the Participating Employee, refunded to
the Participating Employee, except that where such excess is less than the
purchase price for a single share of Stock on the Offering Termination Date,
such excess shall not be refunded but instead shall be carried over and applied
to the purchase of shares in the first following Offering Period (subject to the
possibility of withdrawal by the Participating Employee during such Offering
Period in accordance with the terms of the Plan).

       9.10 DELIVERY OF STOCK. Except as provided below, within a reasonable
time after the Offering Termination Date, the Company shall deliver or cause to
be delivered to the Participating Employee a certificate or certificates for the
number of shares purchased by the Participating Employee. A stock certificate
representing the number of Shares purchased will be issued in the participant's
name only, or if his or her Membership Agreement so specifies, in the name of
the employee and another person of legal age as joint tenants with rights of
survivorship. If any law or applicable regulation of the Securities and Exchange
Commission or other body having jurisdiction in the premises shall require that
the Company or the Participating Employee take any action in connection with the
shares being purchased under the Option, delivery of the certificate or
certificates for such shares shall be postponed until the necessary action shall
have been completed, which action shall be taken by the Company at its own
expense, without unreasonable delay. The Optionee shall have no rights as a
shareholder in respect of shares for which he or she has not received a
certificate.


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       9.11 RETURN OF ACCUMULATED PAYROLL DEDUCTIONS. In the event that the
Participating Employee or the Beneficiary is entitled to the return of
accumulated payroll deductions, whether by reason of voluntary withdrawal,
termination of employment, Retirement, death, or in the event that accumulated
payroll deductions exceed the price of shares purchased, such amount shall be
returned by the Company to the Participating Employee or the Beneficiary, as the
case may be, not later than within a reasonable time following the Offering
Termination Date applicable to the Option Period in which such deductions were
taken. Accumulated payroll deductions held by the Company shall not bear
interest nor shall the Company be obligated to segregate the same from any of
its other assets.


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