BLADDER-CANCER CELLS DO NOT EXPRESS COSTIMULATORY MOLECULES B7-1, B7-2 AND B7-3 - EVIDENCE FOR THE EXISTENCE OF AN ADDITIONAL LIGAND FOR LFA-1

It is widely established that BCG is an effective treatment for transi tional cell carcinoma (TCC). Its clinical benefit might be attributabl e to effects both on immuno-competent cells themselves and the tumour, e.g., the induction of MHC Class II and ICAM-1 expression which are k nown to facilitate effector cell/ target cell interactions. It is of i nterest that the success of this therapy might be due in part to the i nduction of B7 molecules which could provide vital co-stimulatory sign als to the host immune system. We showed that a panel of 8 TCC cell li nes failed to express B7-1,-2,-3 molecules constitutively or after sti mulation. Bladder cancer cells shed following immunotherapy also faile d to express B7. After therapy B7 expression, however, was found on ce lls of lymphocytic and monocytic lineage produced locally. Of other co -stimulatory molecules examined (ICAM-3, HSP72, CD1b, VCAM) only CD40 appeared to be expressed on some of TCC cell lines. All cell lines fai led to express previously predicted ICAM-3 indicating a possible exist ence of a novel ligand for LFA-1.