INDUCTION OF ICAM-1 EXPRESSION ON BLADDER-TUMORS BY BCG IMMUNOTHERAPY

Aims-To determine the expression of intercellular adhesion molecule 1 and 2 (ICAM 1 and 2) in transitional cell carcinoma cells before and a fter immunotherapy with Calmette-Guerin bacillus (BCG). Methods-Frozen sections from 22 untreated bladder carcinomas were immunohistochemica lly examined with monoclonal antibodies to ICAM 1 and 2. Urinary cytos pin slides were made for six patients for each of the six clinical ins tillations which constitute a therapeutic course. These slides were al so stained for ICAM 1 and for leucocyte function associated antigen 1 (LFA 1). Results-Bladder cancer cells did not essentially express eith er ICAM 1 or 2, but cells in the stromal areas Surrounding tumour expr essed both these antigens. After repeated instillations of BCG organis ms ICAM 1 positive normal and neoplastic epithelial cells were observe d in the urine. Cells obtained from the first three instillations expr essed lower densities of ICAM 1 than those from the later instillation s. Many neutrophils expressing LFA-1 and some lymphocytes were also no ted in the cytospin slides and some of these were conjugated to tumour cells expressing ICAM 1. Six months after treatment a single maintena nce dose of BCG induced ICAM 1 expression. Conclusion-Untreated superf icial bladder carcinoma cells do not express ICAM 1 or 2, but these im portant immunological molecules were expressed in the stromal areas of tissue. Importantly, neoplastic cells in the urine expressed ICAM, 1 after immunotherapy. This molecule can render bladder tumour cells vul nerable to non-antigen specific cytotoxicity mediated by activated lym phocytes.