<PAGE>   1
      AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MAY 14, 1998

                                                            FILE NO. 333-______

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                             ----------------------
                                    FORM S-8
                          REGISTRATION STATEMENT UNDER
                           THE SECURITIES ACT OF 1933
                             ----------------------
                                 LEUKOSITE, INC.
             (Exact Name of Registrant as Specified in its Charter)

                       DELAWARE                           04-3173859
           (State or Other Jurisdiction of             (I.R.S. Employer
            Incorporation or Organization)              Identification No.)
                    

                      215 FIRST STREET, CAMBRIDGE, MA 02142
               (Address of Principal Executive Offices) (Zip Code)
                             ----------------------
                                 LEUKOSITE, INC.
                   AMENDED AND RESTATED 1993 STOCK OPTION PLAN
                            (Full Title of the Plan)
                             ----------------------
                         CHRISTOPHER K. MIRABELLI, PH.D.
                       Chairman of the Board of Directors,
                      President and Chief Executive Officer
                                 LEUKOSITE, INC.
                                215 First Street
                         Cambridge, Massachusetts 02142
                     (Name and Address of Agent for Service)

                                 (617) 621-9350
           Telephone Number, Including Area Code, of Agent for Service
                             ----------------------
                                   Copies to:

                            JUSTIN P. MORREALE, ESQ.
                               JULIO E. VEGA, ESQ.
                                BINGHAM DANA LLP
                               150 Federal Street
                              Boston, MA 02110-1726
                                 (617) 951-8000

                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
================================================================================
                                                PROPOSED
                       AMOUNT      MAXIMUM       MAXIMUM
    TITLE OF           TO BE      OFFERING      AGGREGATE            AMOUNT OF 
SECURITIES TO BE     REGISTERED     PRICE        OFFERING          REGISTRATION
   REGISTERED                     PER SHARE  OFFERING PRICE(1)          FEE    
--------------------------------------------------------------------------------
<S>                   <C>         <C>           <C>                 <C>                              
 Common Stock,
 $.01 par value.....  2,125,000      N/A       $13,153,267          $3,881.00
================================================================================
</TABLE>

(1) The proposed maximum offering price has been estimated pursuant to Rule
457(h) solely for the purpose of calculating the registration fee. It is not
known how many shares will be purchased under the Plan or at what price such
shares will be purchased. The estimate of the proposed maximum aggregate
offering price has been calculated based on (i) the offering of 1,432,142
shares, being the portion of the shares of Common Stock registered hereby
subject to outstanding options under the Plan, at a weighted average exercise
price of $5.304 per share, and (ii) the offering of 692,858 shares, being the
aggregate number of shares of Common Stock available for issuance upon exercise
of options to be granted under the Plan, at an exercise price of $8.00 per
share, which is the average of the high and low prices of the Registrant's
Common Stock as listed on the National Association of Securities Dealers
Automated Quotation ("Nasdaq") National Market System on May 8, 1998.


<PAGE>   2


                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.

         The following documents filed by LeukoSite, Inc. (the "REGISTRANT")
with the Securities and Exchange Commission (the "SEC") are hereby incorporated
by reference in this Registration Statement: (1) the Registrant's Annual Report
on Form 10-K for the fiscal year ended December 31, 1997; (2) all reports filed
by the Registrant pursuant to Section 13(a) or 15(d) of the Securities Exchange
Act of 1934, as amended (the "EXCHANGE ACT"), since the end of the Registrant's
1997 fiscal year; and (3) the description of the Common Stock contained in the
Registrant's registration statement on Form 8-A filed with the SEC under Section
12(g) of the Exchange Act, including any amendment or report filed for the
purpose of updating such description.

         In addition, all documents subsequently filed by the Registrant
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act, prior to
the filing of a post-effective amendment which indicates that all securities
offered hereby have been sold or which deregisters all of such securities then
remaining unsold, shall be deemed to be incorporated by reference into this
Registration Statement and to be a part hereof from the date of filing of such
documents.

ITEM 4.  DESCRIPTION OF SECURITIES

         Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS OR COUNSEL

         Not applicable.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Section 145 of the Delaware General Corporation Law empowers a Delaware
corporation to indemnify its officers and directors and certain other persons to
the extent and under the circumstances set forth therein.

         The Restated Certificate of Incorporation and the Amended and Restated
By-Laws of the Company, copies of which are filed herein as Exhibits 4.1 and
4.2, provide for advancement of expenses and indemnification of officers and
directors of the Registrant and certain other persons against liabilities and
expenses incurred by any of them in certain stated proceedings and under certain
stated conditions to the fullest extent permissible under Delaware law.

         The Company intends to maintain insurance for the benefit of its
directors and officers insuring such persons against certain liabilities,
including liabilities under the securities laws.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

         Not applicable.

<PAGE>   3

ITEM 8.  EXHIBITS

         The following exhibits are filed as part of this Registration
Statement:

      4.1     Restated Certificate of Incorporation of the Registrant.
              Incorporated by reference to Exhibit 3.3 to the Registrant's
              Registration Statement Form S-1 (File No. 333-30213).

      4.2     Amended and Restated By-Laws of the Registrant.  Incorporated
              by reference to Exhibit 3.4 to the Registrant's Registration
              Statement on Form S-1 (File No. 333-30213).

        5     Opinion and Consent of Bingham Dana LLP with respect to
              the legality of the shares being registered.

     23.1     Consent of Bingham Dana LLP (included in Exhibit 5).

     23.2     Consent of Arthur Andersen LLP.

       24     Power of Attorney (included in signature page to Registration
                Statement).

ITEM 9.  UNDERTAKINGS

         The undersigned Registrant hereby undertakes:

(1)   To file, during any period in which offers or sales are being made, a
      post-effective amendment to this Registration Statement to include any
      material information with respect to the plan of distribution not
      previously disclosed in this Registration Statement or any material change
      to such information in this Registration Statement;

(2)   That, for the purpose of determining any liability under the Securities
      Act of 1933, as amended (the "SECURITIES ACT"), each such post-effective
      amendment shall be deemed to be a new registration statement relating to
      the securities offered therein, and the offering of such securities at
      that time shall be deemed to be the initial bona fide offering thereof;

(3)   To remove from registration by means of a post-effective amendment any of
      the securities being registered which remain unsold at the termination of
      the offering;

(4)   That, for purposes of determining any liability under the Securities Act,
      each filing of the Registrant's annual report pursuant to Section 13(a) or
      15(d) of the Exchange Act (and, where applicable, each filing of an
      employee benefit plan's annual report pursuant to Section 15(d) of the
      Exchange Act) that is incorporated by reference in the Registration
      Statement shall be deemed to be a new registration statement relating to
      the securities offered therein, and the offering of such securities at
      that time shall be deemed to be the initial bona fide offering thereof;
      and

(5)   Insofar as indemnification for liabilities arising under the Securities
      Act may be permitted to directors, officers and controlling persons of the
      Registrant pursuant to the foregoing provisions, or otherwise, the
      Registrant has been advised that in the opinion of the SEC such
      indemnification is against public policy as expressed in the Securities
      Act and is, therefore, unenforceable. In the event that a claim for
      indemnification against such liabilities (other than the payment by the
      Registrant of expenses incurred or paid by a director, officer or
      controlling person of the Registrant in the successful defense of any
      action, suit or proceeding) is asserted by such director, officer or
      controlling person in connection with the securities being registered, the
      Registrant will, unless in the opinion of its counsel the matter has been
      settled by controlling precedent, submit to a court of appropriate
      jurisdiction the question whether such indemnification by it is against
      public policy as expressed in the Securities Act and will be governed by
      the final adjudication of such issue.

                                       2

<PAGE>   4



                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, as amended,
the Registrant certifies that it has reasonable grounds to believe that it meets
all of the requirements for filing on Form S-8 and has duly caused this
Registration Statement to be signed on its behalf by the undersigned, thereunto
duly authorized, in the City of Cambridge, Commonwealth of Massachusetts, on
this 13th day of May, 1998.

                           LEUKOSITE, INC.

                           By: /s/ Christopher K. Mirabelli
                              --------------------------------------
                              Christopher K. Mirabelli, Ph.D.
                              Chairman of the Board of Directors,
                              President and Chief Executive Officer

                                POWER OF ATTORNEY

         Each person whose signature appears below hereby appoints Christopher
K. Mirabelli and Augustine Lawlor and each of them severally, acting alone and
without the other, his/her true and lawful attorney-in-fact with the authority
to execute in the name of each such person, and to file with the Securities and
Exchange Commission, together with any exhibits thereto and other documents
therewith, any and all amendments (including without limitation post-effective
amendments) to this Registration Statement on Form S-8 necessary or advisable to
enable the Registrant to comply with the Securities Act of 1933, as amended, and
any rules, regulations, and requirements of the Securities and Exchange
Commission in respect thereof, which amendments may make such other changes in
the Registration Statement as the aforesaid attorney-in-fact executing the same
deems appropriate.

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the date indicated.


<TABLE>
<CAPTION>

       SIGNATURE                                     TITLE                                  DATE
       ---------                                     -----                                  ----
<S>                                     <C>                                              <C>
 /s/ Christopher K. Mirabelli           Chairman of the Board of Directors,              May 13, 1998
-----------------------------           President and Chief Executive Officer 
Christopher K. Mirabelli, Ph.D.         (Principal Executive Officer)
       
    /s/ Augustine Lawlor                Vice President,  Corporate Development           May 13, 1998
-----------------------------           and Chief Financial Officer (Principal
      Augustine Lawlor                  Financial and Accounting Officer)
                                                                                                     
    /s/ Kate Bingham                    Director                                         May 13, 1998
-----------------------------           
       Kate Bingham

 /s/ Yasunori Kaneko, M.D.              Director                                         May 13, 1998
-----------------------------           
   Yasunori Kaneko, M.D.

  /s/ John W. Littlechild               Director                                         May 13, 1998
-----------------------------          
    John W. Littlechild
</TABLE>

                                        3
<PAGE>   5

<TABLE>
<CAPTION>
         SIGNATURE                                TITLE                                      DATE
         ---------                                -----                                      ----
<S>                                     <C>                                              <C>

     /s/ Martin Peretz                  Director                                         May 13, 1998
------------------------------           
    Martin Peretz, Ph.D.

    /s/ Mark Skaletsky                  Director                                         May 13, 1998
------------------------------           
      Mark Skaletsky

  /s/ Timothy A. Springer               Director                                         May 13, 1998
------------------------------           
 Timothy A. Springer, Ph.D.

  /s/ Christopher T. Walsh              Director                                         May 13, 1998 
------------------------------
 Christopher T. Walsh, Ph.D.
</TABLE>



                                        4

<PAGE>   6



                                INDEX TO EXHIBITS

 EXHIBIT                                                             
  NUMBER                        DESCRIPTION                          

  4.1   Restated Certificate of Incorporation of the Registrant.  
        Incorporated by reference to Exhibit 3.3 to the Registrant's
        Registration Statement Form S-1 (File No. 333-30213).        

  4.2   Amended and Restated By-Laws of the Registrant.  Incorporated 
        by reference to Exhibit 3.4 to the Registrant's Registration
        Statement on Form S-1 (File No. 333-30213).                  

  5     Opinion and Consent of Bingham Dana LLP with respect
        to the legality of the shares being registered.              

 23.1   Consent of Bingham Dana LLP (included in Exhibit 5).         

 23.2   Consent of Arthur Andersen LLP                               

 24     Power of Attorney (included in signature page to Registration
        Statement).

                                       5
[{"type": "S-8", "sequence": "1", "description": "LEUKOSITE, INC.", "secsgml_size_bytes": 15984}]
{"company-data": {"conformed-name": "LEUKOSITE INC", "cik": "0000915320", "assigned-sic": "2834", "irs-number": "043173859", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-52647", "film-number": "98620491"}, "business-address": {"street1": "215 FIRST ST", "city": "CAMBRIDGE", "state": "MA", "zip": "02142"}, "mail-address": {"street1": "215 FIRST STREET", "city": "CAMBRIDGE", "state": "MA", "zip": "02142"}}
1
      AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MAY 14, 1998

                                                            FILE NO. 333-______

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                             ----------------------
                                    FORM S-8
                          REGISTRATION STATEMENT UNDER
                           THE SECURITIES ACT OF 1933
                             ----------------------
                                 LEUKOSITE, INC.
             (Exact Name of Registrant as Specified in its Charter)

                       DELAWARE                           04-3173859
           (State or Other Jurisdiction of             (I.R.S. Employer
            Incorporation or Organization)              Identification No.)
                    

                      215 FIRST STREET, CAMBRIDGE, MA 02142
               (Address of Principal Executive Offices) (Zip Code)
                             ----------------------
                                 LEUKOSITE, INC.
                   AMENDED AND RESTATED 1993 STOCK OPTION PLAN
                            (Full Title of the Plan)
                             ----------------------
                         CHRISTOPHER K. MIRABELLI, PH.D.
                       Chairman of the Board of Directors,
                      President and Chief Executive Officer
                                 LEUKOSITE, INC.
                                215 First Street
                         Cambridge, Massachusetts 02142
                     (Name and Address of Agent for Service)

                                 (617) 621-9350
           Telephone Number, Including Area Code, of Agent for Service
                             ----------------------
                                   Copies to:

                            JUSTIN P. MORREALE, ESQ.
                               JULIO E. VEGA, ESQ.
                                BINGHAM DANA LLP
                               150 Federal Street
                              Boston, MA 02110-1726
                                 (617) 951-8000

                         CALCULATION OF REGISTRATION FEE
================================================================================
                                                PROPOSED
                       AMOUNT      MAXIMUM       MAXIMUM
    TITLE OF           TO BE      OFFERING      AGGREGATE            AMOUNT OF 
SECURITIES TO BE     REGISTERED     PRICE        OFFERING          REGISTRATION
   REGISTERED                     PER SHARE  OFFERING PRICE(1)          FEE    
--------------------------------------------------------------------------------
Common Stock,
 $.01 par value.....  2,125,000      N/A       $13,153,267          $3,881.00
================================================================================
(1) The proposed maximum offering price has been estimated pursuant to Rule
457(h) solely for the purpose of calculating the registration fee. It is not
known how many shares will be purchased under the Plan or at what price such
shares will be purchased. The estimate of the proposed maximum aggregate
offering price has been calculated based on (i) the offering of 1,432,142
shares, being the portion of the shares of Common Stock registered hereby
subject to outstanding options under the Plan, at a weighted average exercise
price of $5.304 per share, and (ii) the offering of 692,858 shares, being the
aggregate number of shares of Common Stock available for issuance upon exercise
of options to be granted under the Plan, at an exercise price of $8.00 per
share, which is the average of the high and low prices of the Registrant's
Common Stock as listed on the National Association of Securities Dealers
Automated Quotation ("Nasdaq") National Market System on May 8, 1998.
2

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.

         The following documents filed by LeukoSite, Inc. (the "REGISTRANT")
with the Securities and Exchange Commission (the "SEC") are hereby incorporated
by reference in this Registration Statement: (1) the Registrant's Annual Report
on Form 10-K for the fiscal year ended December 31, 1997; (2) all reports filed
by the Registrant pursuant to Section 13(a) or 15(d) of the Securities Exchange
Act of 1934, as amended (the "EXCHANGE ACT"), since the end of the Registrant's
1997 fiscal year; and (3) the description of the Common Stock contained in the
Registrant's registration statement on Form 8-A filed with the SEC under Section
12(g) of the Exchange Act, including any amendment or report filed for the
purpose of updating such description.

         In addition, all documents subsequently filed by the Registrant
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act, prior to
the filing of a post-effective amendment which indicates that all securities
offered hereby have been sold or which deregisters all of such securities then
remaining unsold, shall be deemed to be incorporated by reference into this
Registration Statement and to be a part hereof from the date of filing of such
documents.

ITEM 4.  DESCRIPTION OF SECURITIES

         Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS OR COUNSEL

         Not applicable.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Section 145 of the Delaware General Corporation Law empowers a Delaware
corporation to indemnify its officers and directors and certain other persons to
the extent and under the circumstances set forth therein.

         The Restated Certificate of Incorporation and the Amended and Restated
By-Laws of the Company, copies of which are filed herein as Exhibits 4.1 and
4.2, provide for advancement of expenses and indemnification of officers and
directors of the Registrant and certain other persons against liabilities and
expenses incurred by any of them in certain stated proceedings and under certain
stated conditions to the fullest extent permissible under Delaware law.

         The Company intends to maintain insurance for the benefit of its
directors and officers insuring such persons against certain liabilities,
including liabilities under the securities laws.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

         Not applicable.
3

ITEM 8.  EXHIBITS

         The following exhibits are filed as part of this Registration
Statement:

      4.1     Restated Certificate of Incorporation of the Registrant.
              Incorporated by reference to Exhibit 3.3 to the Registrant's
              Registration Statement Form S-1 (File No. 333-30213).

      4.2     Amended and Restated By-Laws of the Registrant.  Incorporated
              by reference to Exhibit 3.4 to the Registrant's Registration
              Statement on Form S-1 (File No. 333-30213).

        5     Opinion and Consent of Bingham Dana LLP with respect to
              the legality of the shares being registered.

     23.1     Consent of Bingham Dana LLP (included in Exhibit 5).

     23.2     Consent of Arthur Andersen LLP.

       24     Power of Attorney (included in signature page to Registration
                Statement).

ITEM 9.  UNDERTAKINGS

         The undersigned Registrant hereby undertakes:

(1)   To file, during any period in which offers or sales are being made, a
      post-effective amendment to this Registration Statement to include any
      material information with respect to the plan of distribution not
      previously disclosed in this Registration Statement or any material change
      to such information in this Registration Statement;

(2)   That, for the purpose of determining any liability under the Securities
      Act of 1933, as amended (the "SECURITIES ACT"), each such post-effective
      amendment shall be deemed to be a new registration statement relating to
      the securities offered therein, and the offering of such securities at
      that time shall be deemed to be the initial bona fide offering thereof;

(3)   To remove from registration by means of a post-effective amendment any of
      the securities being registered which remain unsold at the termination of
      the offering;

(4)   That, for purposes of determining any liability under the Securities Act,
      each filing of the Registrant's annual report pursuant to Section 13(a) or
      15(d) of the Exchange Act (and, where applicable, each filing of an
      employee benefit plan's annual report pursuant to Section 15(d) of the
      Exchange Act) that is incorporated by reference in the Registration
      Statement shall be deemed to be a new registration statement relating to
      the securities offered therein, and the offering of such securities at
      that time shall be deemed to be the initial bona fide offering thereof;
      and

(5)   Insofar as indemnification for liabilities arising under the Securities
      Act may be permitted to directors, officers and controlling persons of the
      Registrant pursuant to the foregoing provisions, or otherwise, the
      Registrant has been advised that in the opinion of the SEC such
      indemnification is against public policy as expressed in the Securities
      Act and is, therefore, unenforceable. In the event that a claim for
      indemnification against such liabilities (other than the payment by the
      Registrant of expenses incurred or paid by a director, officer or
      controlling person of the Registrant in the successful defense of any
      action, suit or proceeding) is asserted by such director, officer or
      controlling person in connection with the securities being registered, the
      Registrant will, unless in the opinion of its counsel the matter has been
      settled by controlling precedent, submit to a court of appropriate
      jurisdiction the question whether such indemnification by it is against
      public policy as expressed in the Securities Act and will be governed by
      the final adjudication of such issue.

                                       2
4

                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, as amended,
the Registrant certifies that it has reasonable grounds to believe that it meets
all of the requirements for filing on Form S-8 and has duly caused this
Registration Statement to be signed on its behalf by the undersigned, thereunto
duly authorized, in the City of Cambridge, Commonwealth of Massachusetts, on
this 13th day of May, 1998.

                           LEUKOSITE, INC.

                           By: /s/ Christopher K. Mirabelli
                              --------------------------------------
                              Christopher K. Mirabelli, Ph.D.
                              Chairman of the Board of Directors,
                              President and Chief Executive Officer

                                POWER OF ATTORNEY

         Each person whose signature appears below hereby appoints Christopher
K. Mirabelli and Augustine Lawlor and each of them severally, acting alone and
without the other, his/her true and lawful attorney-in-fact with the authority
to execute in the name of each such person, and to file with the Securities and
Exchange Commission, together with any exhibits thereto and other documents
therewith, any and all amendments (including without limitation post-effective
amendments) to this Registration Statement on Form S-8 necessary or advisable to
enable the Registrant to comply with the Securities Act of 1933, as amended, and
any rules, regulations, and requirements of the Securities and Exchange
Commission in respect thereof, which amendments may make such other changes in
the Registration Statement as the aforesaid attorney-in-fact executing the same
deems appropriate.

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the date indicated.
SIGNATURE                                     TITLE                                  DATE
       ---------                                     -----                                  ----
/s/ Christopher K. Mirabelli           Chairman of the Board of Directors,              May 13, 1998
-----------------------------           President and Chief Executive Officer 
Christopher K. Mirabelli, Ph.D.         (Principal Executive Officer)
       
    /s/ Augustine Lawlor                Vice President,  Corporate Development           May 13, 1998
-----------------------------           and Chief Financial Officer (Principal
      Augustine Lawlor                  Financial and Accounting Officer)
                                                                                                     
    /s/ Kate Bingham                    Director                                         May 13, 1998
-----------------------------           
       Kate Bingham

 /s/ Yasunori Kaneko, M.D.              Director                                         May 13, 1998
-----------------------------           
   Yasunori Kaneko, M.D.

  /s/ John W. Littlechild               Director                                         May 13, 1998
-----------------------------          
    John W. Littlechild
3
5
SIGNATURE                                TITLE                                      DATE
         ---------                                -----                                      ----
/s/ Martin Peretz                  Director                                         May 13, 1998
------------------------------           
    Martin Peretz, Ph.D.

    /s/ Mark Skaletsky                  Director                                         May 13, 1998
------------------------------           
      Mark Skaletsky

  /s/ Timothy A. Springer               Director                                         May 13, 1998
------------------------------           
 Timothy A. Springer, Ph.D.

  /s/ Christopher T. Walsh              Director                                         May 13, 1998 
------------------------------
 Christopher T. Walsh, Ph.D.
4
6

                                INDEX TO EXHIBITS

 EXHIBIT                                                             
  NUMBER                        DESCRIPTION                          

  4.1   Restated Certificate of Incorporation of the Registrant.  
        Incorporated by reference to Exhibit 3.3 to the Registrant's
        Registration Statement Form S-1 (File No. 333-30213).        

  4.2   Amended and Restated By-Laws of the Registrant.  Incorporated 
        by reference to Exhibit 3.4 to the Registrant's Registration
        Statement on Form S-1 (File No. 333-30213).                  

  5     Opinion and Consent of Bingham Dana LLP with respect
        to the legality of the shares being registered.              

 23.1   Consent of Bingham Dana LLP (included in Exhibit 5).         

 23.2   Consent of Arthur Andersen LLP                               

 24     Power of Attorney (included in signature page to Registration
        Statement).

                                       5