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Biomedical subjects

J Forman

Publications and source records attributed to J Forman.

At least 181 records · Page 10Linked to original sources
PubMed1973

Generation of cytotoxic lymphocytes in mixed lymphocyte reactions. I. Specificity of the effector cells.

Generation of cytotoxic effector cells by a unidirectional mixed lymphocyte reaction (MLR) in the mouse H-2 system was studied using labeled YAC (H-2(a)) leukemia cells as targets. The responding effector cell displayed a specific cytotoxic effect against target cells of the same H-2 genotype as the stimulating cell population. Killing of syngeneic H-2 cells was not observed, even when the labeled target cells were "innocent bystanders" in cultures where specific target cells were reintroduced. Similar results were found with spleen cells taken from mice sensitized in vivo 7 days earlier. The effector cell was not an adherent cell and was not activated by supernatants from MLR. The supernatants were not cytotoxic by themselves. When concanavalin A or phytohemagglutinin was added to the cytotoxic test system, target and effector cells were agglutinated. Under these conditions, killing of H-2(a) target cells was observed in mixed cultures where H-2(a) lymphocytes were also the effector cells. These findings indicate that specifically activated, probably thymus-derived lymphocytes, can kill nonspecifically once they have been activated and providing there is close contact between effector and target cells. Thus, specificity of T cell killing appears to be restricted to recognition and subsequent binding to the targets, the actual effector phase being nonspecific.

Animals↗
PubMed1973

Heterogeneity of the effector cells in the cytotoxic reaction against allogeneic lymphoma cells.

The cytotoxic effect of spleen cells from H-2 allogeneic mice was tested in vitro against an A strain leukemia (YAC) labeled with [(125)I]iododeoxyuridine. After the mice were primed with tumor cells, significant and specific H-2 immunity was detected on day 3 and peak cytotoxicity was observed between 7 and 14 days after priming. Two effector cells appear to be involved in the host response, because spleens taken from mice soon after priming were not sensitive to antitheta sera and complement while those taken during the peak stages of the response showed a marked reduction in cytotoxicity after treatment. Macrophages were not involved, since removal of these cells by the carbonyl iron method did not result in any reduction in cytotoxicity. Immune serum that was capable of inducing cell-mediated cytotoxicity in normal spleen cell populations also augmented cytotoxicity of spleen cells taken from mice primed 3 days previously. However, when spleen cells were taken from mice during the peak phase of the immune response, the same serum at the same dilutions inhibited the preexisting cytotoxicity. A difference was also detected in the killing efficiencies between early and late immune cells.

Animals↗