Suppressor cell activities in autologous human tumor systems. Suppression of tumor immunity

Autologous T-cell clones or lines, established from peripheral blood lymphocytes (PBLs) and lymphocytes from tumor-affected lymph nodes, were used to examine the immunoregulatory circuitry that might influence cell-mediated cytotoxic responses against human cancers. In a chromium 51-release microcytotoxicity assay, PBLs, when activated in vitro against autologous tumor cells in interleukin-2, generated marked cytotoxicity against the autologous targets. In four solid-tumor systems, such generation of cytotoxicity in the PBLs could be suppressed by T-cell lines or clones derived from lymphocytes from tumor-affected lymph nodes (LNLs). The suppressions, mediated by both T8+ suppressor and T4+ suppressor-inducer cells, were restricted against only the autologous tumors in two systems. In the other cases, the suppressions were nonspecific. Clarification of the receptors through which these types of regulation are mediated might provide a new approach for immunotherapeutic manipulations in cancer.