Background: This study investigated changes in the phenotypic characteristics of tumor-infiltrating lymphocytes during intravesical bacillus Calmette-Guérin (BCG) treatment using an immunohistochemical technique.
Methods: A total of 16 patients with superficial bladder cancer underwent intravesical BCG treatment for therapeutic purposes. Tissue specimens were obtained from these patients before and after BCG treatment by cold cup biopsies.
Results: The numbers of CD3+ cells, CD4+ cells, CD8+ cells, and CD19+ cells significantly increased after treatment compared with numbers before treatment (P < 0.01). Although gamma/delta T cells were not observed before treatment, they appeared after treatment in 6 patients. In all these patients, the tumors disappeared or their size was reduced by more than 50%, and none of the tumors recurred. The induction of CD25+ cells after treatment was seen in 11 of the 16 patients.
Conclusion: gamma/delta T cells may play an important role in the immune response of the host to the tumor in intravesical BCG treatment (although this correlation was statistically insignificant.