Reactivity of tumor-infiltrating, blood, spleen and lymph node lymphocytes against syngeneic glioma target cells.

Brain tumors were induced in inbred Fischer rats (F344) by administration of methylnitrosourea in the drinking water. One of the induced tumors, a pleomorphic glioma (78-219), was established in vitro and propagated as 78FR-G-219 permanent cell line. The tumorigenicity of the established line was investigated by intracerebral or subcutaneous inoculation of 1X10 (6) - 10X10(6) cells. Lymphocytes infiltrating secondary tumors (TIL) were enriched by a single step centrifugation on different discontinuous Percoll density gradients, while blood lymphocytes (PBL) and lymphocytes from spleen and lymph node (SL and LNL) were enriched by Ficoll - Isopaque flotation. The reactivity spectrum of the isolated lymphocytes raised against cultured 78FR-G-219 cells was monitored by means of two different assays: Lymphocyte microcytotoxicity test (LMC) and colony inhibition assay (CIA). Reactivity of PBL, SL and LNL of glioma-bearing animals was clearly reduced, while TIL showed no natural killer (NK) activity, no cytotoxicity against syngeneic 78FR-G-219 pleomorphic glioma cells and no colony inhibition in mixed lymphocyte/target cell cocultivation. NK activity of TIL was only slightly reduced against target cells of a non-cross-reacting syngeneic astrocytoma line (78FR-G-299).