Proliferative and cytolytic responses of human gamma delta T cells display a distinct specificity pattern.
The function and physiological role of gamma delta T cells are still unknown. Concerning the specificity of these cells, a proliferative response towards microbial ligands has been noted, whereas in terms of effector functions in humans a cytolytic activity against a variety of tumour targets is most prominent. Here we show data demonstrating that the cytolytic activity of activated human gamma delta T cells does not reflect the specificity of these cells in primary in vitro stimulation; moreover, we provide evidence that the recognition of target cells by gamma delta T cells can have different qualities. gamma delta T cells proliferate vigorously in primary in vitro reaction upon stimulation with various B-cell tumour lines but not with the T-cell lines Jurkat or Molt-4. However, gamma delta T cells stimulated primarily with phytohaemagglutinin or with cells from B-cell lines gain unrestricted cytolytic activity against a broad set of tumour targets, including Jurkat and Molt-4; the same set of targets is capable of inducing release of serine esterases (SE) from gamma delta T-effector cells. Whereas the cytolytic activity in the 51Cr-assay against the B-cell lines and against Molt-4 depends on the presence of Ca2+ ions in the assay, the lysis of Jurkat cells is only slightly reduced upon removal of Ca2+ from the medium; the SE release, however, is Ca2+ dependent in all cases. Taken together, these data suggest several different ways of target cell recognition by gamma delta T cells leading to either proliferation or triggering of cytolytic activity, and argue against an involvement of the gamma delta T-cell receptor in the cytotoxic activity of gamma delta T cells.
Institute of Medical Microbiology and Hygiene, Technical University of Munich, Germany.
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Haecker
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Wagner
D002118:Calcium / Q000502:physiology; D002455:Cell Division / Q000276:immunology; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic / Q000276:immunology*; D004950:Esterases / Q000097:blood; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000032:analysis*; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology*; D014407:Tumor Cells, Cultured
D016692:Receptors, Antigen, T-Cell, gamma-delta; D004950:Esterases; C022635:serine esterase; D002118:Calcium