5 Deloitte & Touche LLP Two Hilton Court PO Box 319 Parsippany, New Jersey 07054-0319 Telephone: (973) 683-7000 Facsimile: (973) 683-7459 February 3, 2000 Isidore S. Edelman, M.D. Chairman & Chief Executive Officer Cistron Biotechnology Inc. P.O. Box 2004 10 Bloomfield avenue Pine Brook, NJ 07058 Dear Dr. Edelman: This is to confirm that the client-auditor relationship between Cistron Biotechnology, Inc. (Comission File No. 0-15271) and Deloitte & Touche LLP has ceased. Yours truly, /s/Deloitte & Touche LLP - - ------------------------ Deloitte & Touche LLP Cc:	Office of the Chief Accountant 	SECOS Letter File 	Securities and Exchange Commission 	Mail Stop 9-5 	450 5th Street, N.W. 	Washington, D.C. 20549