Fas ligand and TNF-related apoptosis-inducing ligand induction on infiltrating lymphocytes in bladder carcinoma by bacillus Calmette-Guérin treatment.

AIM: To determine the molecular mechanisms underlying the efficacy of bacillus Calmette-Guérin (BCG) therapy against superficial carcinoma of the urinary bladder, we evaluated the expression of cytotoxic molecules on tumor-infiltrating lymphocytes before and after therapy.

METHODS

Immunofluorescence staining allowed the specific detection of Fas, Fas ligand (FasL), and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) expression on tumor cells and the respective leukocyte populations in biopsy samples from 6 patients.

RESULTS

Significant increases in the infiltration of FasL- and TRAIL-expressing CD4+ T cells and macrophages and FasL-expressing CD8+ T and NK cells were observed after BCG instillation in bladder carcinoma. Moreover, Fas expression was upregulated on tumor cells after BCG instillation.

CONCLUSION

The data suggested that the enhanced infiltration of FasL- and/or TRAIL-expressing leukocytes (CD4+ T cells, CD8+ T cells, natural killer cells and macrophages) and the induction of Fas expression on tumor cells may play an important role in the therapeutic effect of BCG instillation.