Cytolytic activity of T lymphocytes isolated from ovarian carcinoma ascitic fluid. Analysis at the population and clonal level

T lymphocytes were isolated from ascitic fluid of three patients with ovarian carcinoma at III-IV stage. Surface markers analysis of such purified T cells revealed that T8⁺ cells were well represented among ascitic T lymphocytes (from 35 to 56%). Low percentages of activated T cells, as indicated by HLA-DR and TAC (interleukin-2 receptor) positivity, were also present. However, fresh ascitic T lymphocytes failed to lyse autologous tumor target cells in a 4-h⁵¹Cr release assay. Furthermore, by applying a limiting dilution microculture system that allows optimal conditions for cloning of human T lymphocytes, we derived clones from these populations. From 41 to 63% of clones so obtained had cytolytic activity in a lectin-dependent assay allowing detection of cytolytic T cells of any specificity. More importantly, in all three patients several clones were found to lyse autologous tumor target cells as well. Some of these clones have been studied in more detail: 9 out of 10 expressed the T8⁺/T4^- phenotype, whereas only one was T8^-/T4⁺; 6 out of 9 clones had a definite NK-like activity, while none of them lysed autologous PHA-lymphoblasts.