Heightened interferon-gamma production by mononuclear cells from bladder cancer patients

Interferon-gamma (IFN-gamma) production by peripheral blood leukocytes from bladder cancer patients was compared with that of patients with prostate cancer and benign prostatic hyperplasia, nontumor-bearing patients with bacterial infections, and normal controls. Leukocyte preparations including mononuclear cells isolated on a Ficoll-Hypaque density gradient (Fraction 2) and glass-nonadherent mononuclear cells (Fraction 3) were stimulated with Protein A from Staphylococcus aureus, and IFN-gamma production was monitored 24 hr later. The class of interferon produced was identified by antibody neutralization experiments which clearly showed S. aureus Protein A-induced interferon to be IFN-gamma. There was significantly heightened IFN-gamma production by Fraction 3 cells from bladder cancer patients and patients with bacterial infections. Heightened IFN-gamma production by bladder cancer patients was not observed in the Fraction 2 cells. No correlation was observed between IFN-gamma production and patients with invasive or noninvasive bladder cancer, but IFN-gamma production was lower in patients having Stage C or D tumors than in those having Stage A or B tumors. These results in conjunction with previous reports demonstrating heightened IFN-gamma production during periods of antigenic stimulation suggest that bladder tumors may induce a cell-mediated immune response in the host as evidenced by the elevation in IFN-gamma production. Moreover, the results suggest that macrophages may be important regulators of IFN-gamma production in bladder cancer patients.