EXHIBIT 99.1


FOR IMMEDIATE RELEASE

Contact:
Clare Midgley (investor)                             Gina Brazier
Sally McCraven (media)                               (investor and media)
Millennium Pharmaceuticals, Inc.                     LeukoSite, Inc.
(617)-679-7480                                       (617) 621-9350, ext. 1830
(617)-577-3548

              MILLENNIUM AND LEUKOSITE AGREE TO MERGE TO ACCELERATE
                   MILLENNIUM'S MOVE TOWARD COMMERCIALIZATION

            -- PROVIDES MILLENNIUM WITH ENHANCED CLINICAL DEVELOPMENT
                      CAPABILITIES AND PRODUCT PIPELINE --

CAMBRIDGE, MASS., OCTOBER 14, 1999 -- Millennium Pharmaceuticals, Inc. (Nasdaq:
MLNM) and LeukoSite, Inc. (Nasdaq: LKST) today announced that they have signed a
merger agreement for Millennium to acquire LeukoSite in a stock-for-stock
exchange. This merger will move Millennium further downstream along the
gene-to-patient continuum by providing important later stage drug development
capabilities, a product expected to be on the market in 2000, a pipeline of
therapeutic product candidates in clinical development and several additional
product candidates in late stage preclinical development.

Under the terms of the merger agreement, which is expected to close in early
2000, LeukoSite shareholders will receive 0.4296 shares of newly issued
Millennium common stock in exchange for each LeukoSite share. Using Millennium's
stock price at the close of business today, this would result in a purchase
price of $35.86/share for LeukoSite stock, a 48.67% premium to today's close.

As a result of this transaction, Millennium expects to issue a total of 7.6
million shares and options, including approximately 1 million options related to
issued warrants and options at LeukoSite. The 7.6 million shares and options
would equate to approximately $635 million in total value at today's price. The
merger will be accounted for using the purchase method of accounting and will
result in significant in-process research and development and goodwill charges
post-closing. The merger is subject to approval by LeukoSite shareholders and to
Hart Scott Rodino clearance.

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MILLENNIUM AND LEUKOSITE AGREE TO MERGE TO ACCELERATE MILLENNIUM'S MOVE
TOWARD COMMERCIALIZATION

"LeukoSite is an ideal complement to Millennium; we will gain critical
downstream technical capabilities, expert teams in late stage clinical
development, and a portfolio of exciting small molecule and biotherapeutic
product candidates in preclinical and clinical development," said Mark Levin,
chief executive officer of Millennium. "We believe our merger with LeukoSite
will be a major step forward in building the biopharmaceutical company of the
future and creating significant shareholder value," Mr. Levin added.

"We expect the combination of Millennium's rich, early-stage pipeline and
integrated technology platform with LeukoSite's drug discovery, preclinical and
clinical development expertise, in addition to our shared strength in product
discovery, will help create a powerful product-focused biopharmaceutical
company," said Christopher Mirabelli, Ph.D., chairman and chief executive
officer of LeukoSite. "Like Millennium, LeukoSite places great value on
superlative science and on cultivating an environment where outstanding
employees can excel. Based on this tremendous foundation and shared vision,
together, we will drive toward the creation of a powerful, fully integrated
biopharmaceutical company."

LeukoSite will bring to Millennium a combined small molecule and biotherapeutic
pipeline in oncology and inflammation that is complementary to Millennium's
expertise in these areas. In addition to its drug discovery and development
capabilities, LeukoSite also brings expertise in chemistry and in the
development of monoclonal antibody products. Further, LeukoSite has extensive
clinical development and regulatory experience.

Millennium and LeukoSite both view mergers, acquisitions, alliances and
collaborations as critical strategic components in the creation of a robust
pipeline of products. The combined company has been involved in four
mergers/acquisitions over the past three years and will have significant
research and development funding through 19 alliances. Additionally, Millennium
intends to continue acquiring companies with strong platform capabilities,
pipelines and employees to build the biopharmaceutical company of the future.

Following the merger, Dr. Mirabelli will join the company and become a member of
the Millennium board of directors.

PRODUCTS IN DEVELOPMENT The merger with LeukoSite provides Millennium with
five products in clinical development. CAMPATH(Registered Trademark), a
humanized monoclonal antibody for the treatment of refractory chronic
lymphocytic leukemia (CLL), is the most advanced drug candidate. Pivotal
clinical trial data demonstrated a 33% objective major response rate in
patients with no other treatment alternatives.

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MILLENNIUM AND LEUKOSITE AGREE TO MERGE TO ACCELERATE MILLENNIUM'S MOVE
TOWARD COMMERCIALIZATION

CAMPATH(Registered Trademark) is expected to receive regulatory review in the
first half of 2000. The FDA has granted fast-track review status to the
marketing application due to the product's potential to help critically ill
patients who have no viable therapeutic alternative. Product approval by the
FDA is expected in the second half of 2000. Clinical trials are ongoing or
planned for additional indications including expanded use in CLL,
non-Hodgkins lymphoma and multiple sclerosis.

CAMPATH(Registered Trademark) is being developed in a 50-50 joint venture
with Ilex Oncology, Inc. (NASDAQ: ILXO). Schering AG/Berlex will
commercialize CAMPATH(Registered Trademark) in the U.S. and Europe, while
LeukoSite and Ilex Oncology have reserved the right to commercialize
CAMPATH(Registered Trademark) in certain Asian Pacific Rim countries.
LeukoSite, Ilex Oncology and Schering AG each will receive one-third of U.S.
profits while equivalent royalties will be distributed on European sales.

LDP-02, a humanized monoclonal antibody product for inflammatory bowel disease,
has shown initial biological activity in clinical studies and recently completed
a Phase IIa trial for the treatment of ulcerative colitis. An additional Phase
IIa trial for the treatment of Crohn's disease is expected to begin in the
fourth quarter of this year. The product is being developed as part of a
strategic alliance between LeukoSite and Genentech, Inc.

Other products in clinical development include: LDP-01, a humanized monoclonal
antibody for stroke, in Phase IIa trials; LDP-977, a small molecule drug
candidate for asthma, with Phase I trials completed and Phase II trials
scheduled to begin in the fourth quarter of 1999; and, LDP-341, a small molecule
drug candidate for cancer, in Phase I trials.

LeukoSite also has nine partnered preclinical drug development programs in
several disease areas including: asthma, allergy, rheumatoid arthritis, multiple
sclerosis, transplantation, HIV and restenosis. Collaborators for these programs
are: Warner-Lambert, Roche BioSciences and Kyowa Hakko Kogyo.

MILLENNIUM AND MILLENNIUM BIOTHERAPEUTICS SUBSIDIARY MERGE
In other news issued today, Millennium announced plans to further enhance its
antibody and protein therapeutics pipeline through a merger with its Millennium
BioTherapeutics subsidiary (MBio). This move will combine MBio's research and
development with Millennium's pharmaceutical division to form a unified pipeline
in small molecules, therapeutic proteins and antibodies and allow Millennium to
focus on later stage drug development.




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MILLENNIUM AND LEUKOSITE AGREE TO MERGE TO ACCELERATE MILLENNIUM'S MOVE
TOWARD COMMERCIALIZATION

The addition of LeukoSite's antibody and small molecule pipeline to Millennium's
combined therapeutics pipeline is expected to strengthen Millennium's
comprehensive and promising portfolio of products in development.

"As we look ahead, 2000 is going to be a tremendously exciting year for
Millennium. We expect to have a Diagnomics(TM) product and a therapeutic
drug, CAMPATH(Registered Trademark), on the market, a very deep pipeline of
both antibodies and small molecules, and what we believe to be the most
comprehensive, integrated technology platform in the industry. Moreover, we
will continue to set our sights higher and make major moves throughout the
year," Mr. Levin added.

LeukoSite is a biotechnology company developing proprietary monoclonal antibody
and small molecule drugs to treat patients with cancer and inflammatory,
autoimmune and viral diseases. Headquartered in Cambridge, Massachusetts,
LeukoSite currently employs approximately 150 people.

Millennium, a leading drug discovery and development company, employs
large-scale genetics, genomics, high throughput screening and informatics in an
integrated science and technology platform. This innovative drug discovery
platform is applied across the entire healthcare sector, from gene
identification through patient management, to accelerate and transform the
discovery and development of proprietary therapeutic and Diagnomics(TM) products
and services. Headquartered in Cambridge, Massachusetts, Millennium and its
affiliates currently employ more than 800 people. Subsequent to the merger, the
combined company will employ approximately 1,000 people.

FOR MILLENNIUM: THIS PRESS RELEASE CONTAINS FORWARD-LOOKING STATEMENTS THAT
INVOLVE A NUMBER OF RISKS AND UNCERTAINTIES. AMONG THE FACTORS THAT COULD CAUSE
ACTUAL RESULTS TO DIFFER MATERIALLY FROM THOSE INDICATED IN SUCH FORWARD LOOKING
STATEMENTS INCLUDE UNCERTAINTIES RELATING TO GENE IDENTIFICATION, DRUG DISCOVERY
AND CLINICAL DEVELOPMENT PROCESSES; CHANGES IN RELATIONSHIPS WITH STRATEGIC
PARTNERS AND DEPENDENCE UPON STRATEGIC PARTNERS FOR THE PERFORMANCE OF CRITICAL
ACTIVITIES UNDER COLLABORATIVE AGREEMENTS; THE IMPACT OF COMPETITIVE PRODUCTS
AND TECHNOLOGICAL CHANGES; UNCERTAINTIES RELATING TO PATENT PROTECTION AND
REGULATORY APPROVAL; AND UNCERTAINTIES RELATING TO THE ABILITY OF MILLENNIUM AND
ITS AFFILIATES TO OBTAIN THE SUBSTANTIAL ADDITIONAL FUNDS REQUIRED FOR PROGRESS
IN DRUG DISCOVERY AND DEVELOPMENT. THE FACTORS THAT COULD AFFECT MILLENNIUM'S
PERFORMANCE ARE MORE FULLY DESCRIBED IN FILINGS BY MILLENNIUM WITH THE
SECURITIES AND EXCHANGE COMMISSION INCLUDING BUT NOT LIMITED TO THE FACTORS SET
FORTH UNDER THE HEADING "BUSINESS - FACTORS THAT MAY AFFECT RESULTS" IN THE
ANNUAL REPORT ON FORM 10-K OF MILLENNIUM FOR THE YEAR ENDED DECEMBER 31, 1998 AS
FILED ON MARCH 24, 1999.



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FOR LEUKOSITE: CERTAIN STATEMENTS CONTAINED HEREIN ARE "FORWARD-LOOKING"
STATEMENTS (AS SUCH TERM IS DEFINED IN THE PRIVATE SECURITIES LITIGATION REFORM
ACT OF 1995). BECAUSE SUCH STATEMENTS INCLUDE RISKS AND UNCERTAINTIES, ACTUAL
RESULTS MAY DIFFER MATERIALLY FROM THOSE EXPRESSED OR IMPLIED BY SUCH
FORWARD-LOOKING STATEMENTS. FACTORS THAT COULD CAUSE ACTUAL RESULTS TO DIFFER
MATERIALLY FROM THOSE EXPRESSED OR IMPLIED BY SUCH FORWARD-LOOKING STATEMENTS
INCLUDE, BUT ARE NOT LIMITED TO, RISKS IN TECHNOLOGY AND PRODUCT DEVELOPMENT,
FAILURE TO SUCCESSFULLY COMPLETE CLINICAL TRIALS, FAILURE TO RECEIVE MARKET
CLEARANCE FROM REGULATORY AGENCIES, COMPETITIVE RISKS AND THOSE RISKS AND
UNCERTAINTIES DISCUSSED IN FILINGS MADE BY LEUKOSITE, INC. WITH THE SECURITIES
AND EXCHANGE COMMISSION. THE COMPANY DISCLAIMS ANY OBLIGATION TO UPDATE THESE
FORWARD-LOOKING STATEMENTS.


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Editor's Note: Reference additional press release distributed today titled
"Millennium Pharmaceuticals Enhances Pipeline in Antibody and Protein
Therapeutics Through Merger of Millennium BioTherapeutics Subsidiary" via PR
Newswire or company website.

Editor's Note: This release is available on Millennium's website at:
http://www.mlnm.com