Evaluation of local immune response after intravesical bacille Calmette-Guerin treatment for superficial bladder cancer

Objective To help define the optimal protocol of Bacille Calmette-Guerin (BCG) treatment for transitional cell carcinoma (TCC) of the bladder by examining cytokine production and antigen presentation to effector cells after instillations of BCG in patients with bladder TCC. Patients and methods Sixty-four urine samples from 11 patients were tested for the production of interferon gamma (IFN-gamma) using a modified commercial enzyme-linked immunosorbent assay (ELISA) kit. Urine was collected before and at intervals up to 24 h after the intravesical instillation of BCG. Immunohistological studies were also carried out using a two-step alkaline phosphatase technique to explore the expression of tumour-associated antigens (TAAs) (E7, 19A211, T138), major histocompatibility complex (MHC) molecules and lymphocyte subset infiltrates (CD3, CD4, CD8) in bladder biopsies before and 3 weeks after the completion of treatment in seven patients. Results IFN-gamma was only detected 4, 6 and 8 h after instillation, with a maximum concentration at 6 h (2.9-34.7 IU/mL in 10 patients). During a 6-week course of BCG, IFN-gamma was barely detectable after the first two instillations, but gradually increased from the third instillation onwards. TAA and MHC II antigens, which were absent or faintly expressed on normal urothelial cells before treatment, were expressed strongly in five patients after treatment. The local recruitment of immunocompetent cells was detected in all patients. Conclusion These results suggest that the local immune response after the intravesical instillation of BCG can be quantified using simple ELISA tests and could be useful in defining objective criteria for rationalizing treatment (dose and duration), and in determining the relation between the immune response and antitumour activity. There is evidence that antigen presentation is enhanced after BCG instillations, suggesting that a T cell-MHC restricted pathway might be involved in the anti-tumour response. This study supports the search for tumour-rejection antigens in bladder cancer.