Immunoresponse of tissue infiltrating lymphocytes in bladder tumors

Local immunocompetence was evaluated immunohistochemically in patients with bladder tumors before and after local injections of an immunomodulator. The subpopulations of tissue infiltrating lymphocytes (TIL) were examined by staining six serial sections with Leu4, Leu7, Leu10, LeuM3, OKT4, and OKT8 antibodies. T cells predominated over B cells in 19 of 25 bladder tumors. T cell infiltration was prominent around tumor cells, and it was marked in non-invasive tumors. B cells were rare in the stroma. In patients with low-stage tumors, OKT8 cells were more prominent than OKT4 cells. NK cells accumulated within cancer nests but their infiltration was scanty in invasive bladder tumors. Before surgery, immunomodulators (OK-432, IL-2) were injected intratumorally. Their administration resulted in marked increase of T and NK cells, irrespective of the stage of disease; there was a slight increase in B cells. These findings suggest that local immunosurveillance plays a role against bladder tumors. Further studies are required to elucidate host immune responses in the microenvironment of the cancer site, as well as the systemic immune reaction.