Increased proportion of CD8+ tumor responsive T cells after immunization with tum- versus tum+ rat glioma.
Previously established immunogenic (tum-) clones of an ENU (ethyl-N-nitrosourea)-induced rat glioma, N32, were compared to the original tumor concerning their capacity to induce T lymphocyte responses after in vivo immunization and in vitro restimulation of responder spleen cells in mixed lymphocyte tumor culture (MLTC) assays. Quite unexpectedly, original N32 (tum+) in vivo primed spleen cells proliferated to the same extent in vitro in response to tum+ stimulator cells as did tum- in vivo primed spleen cells. However, flow-cytometric analysis of parallel cultures showed a greatly increased proportion of CD3+CD8+ lymphocytes in the proliferating responder cell population from tum- immunized hosts, contrary to a CD3+CD4+ lymphocyte dominance after tum+ immunization. Although the original tum+ N32 tumor cells are not capable of inducing a clearly demonstrable isograft rejection response, they induce a strong T cell response readily detectable in MLTC assays. We propose that the increased CD8+ lymphocyte proliferation could be an essential feature of the isograft rejection response induced by tum- tumor variants. Possible mechanisms of the augmented CD8+ T cell response are discussed.
Siesjö
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Department of Tumor Immunology, Wallenberg Laboratory, University of Lund, Sweden.
Visse
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Sjögren
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D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D005434:Flow Cytometry; D005910:Glioma / Q000276:immunology*; D006084:Graft Rejection; D007114:Immunization; D008213:Lymphocyte Activation; D051381:Rats; D011916:Rats, Inbred F344; D014185:Transplantation, Isogeneic; D014407:Tumor Cells, Cultured