CONTACT:  Hal Smith
								1-800-743-6632

								FOR IMMEDIATE RELEASE


CISTRON STOCKHOLDERS TO MEET NOV. 2 RE CELLTECH MERGER	;
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         	ORIGINAL MERGER AGREEMENT AMENDED
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    	PARSIPPANY, N.J. - September 1, 2000 Cistron Biotechnology,
Inc. (OTC:CIST) has called a special stockholders meeting for
November 2 to vote on a merger with Celltech Group plc (NYSE:CLL;
LSE:CCH).  The meeting will be held at the Marriott Glenpoint in
Teaneck, N.J. beginning at 10:00 A.M. Stockholders of record as
of September 12 will be entitled to vote.

    	Under the merger agreement, Celltech will purchase Cistron
for approximately $18.17 million.  This includes $8.75 million
for Cistron's anti-interleukin-1 beta (IL-1 beta) antibody
intellectual property and about $9.42 million for Cistron's cash
reserves.  The purchase will be made with Celltech American
Depository shares. Each share has a value of $40.89, based on the
five-day trailing average through March 20, 2000.

    	Cistron also announced today that the merger agreement has
been amended to eliminate the provision for payment of up to $3.5
million in cash and up to $3.5 million in Celltech stock to
Cistron stockholders in the event that Aventis Pasteur,
subsidiary of Aventis S.A. (NYSE:AVE), exercised the options
previously granted by Cistron to acquire exclusive licenses to
use the IL-1 beta technology in the fields of therapeutic and
preventative vaccines.

    	The merger agreement was amended following termination of a
collaboration and option agreement on August 24 between Cistron
and Aventis Pasteur, including Aventis Pasteur's right to
exercise options to acquire licenses to the IL-1 beta technology.

    	The merger is subject to various conditions, including
approval by appropriate governmental agencies and Cistron's
stockholders.

    	Celltech Group, based in Slough, Berkshire in the UK, is a
major European-based biopharmaceutical company with substantial
operations in the U.S.  The group undertakes drug discovery,
development and international marketing.  Celltech is listed on
both the New York and London Stock Exchanges.

    	Cistron, headquartered in Parsippany, N.J., was founded in
1984.  It is a biotechnology company that uses recombinant DNA
and immunological techniques to explore certain cytokines and
antibodies that may have therapeutic or diagnostic applications.

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    	Cistron Biotechnology, Inc. stockholders and security
holders are urged to read the proxy statement/prospectus
regarding the merger transaction when it becomes available.  The
proxy statement/prospectus will contain important information
that stockholders and security holders should consider before
making any decision regarding the merger.  The proxy
statement/prospectus will be filed with the Securities and
Exchange Commission by Celltech Group plc and Cistron
Biotechnology, Inc.  Stockholders and security holders may obtain
a free copy of the proxy statement/prospectus when it is
available from Cistron Biotechnology, Inc. by directing a request
to Cistron Biotechnology, Inc., P.O. Box 2004, Pine Brook, New
Jersey 07058: telephone: (973)575-1700, e-mail:
info@cistronbio.com.