| Abstrakt: |
Human γδ T cells respond to a wide range of ligands including some T lymphocyte cellular antigens associated with viral infection. In the present study we examined the participation of γδ T cells in the proliferative response that is induced in human peripheral blood mononuclear cells (PBMC) by activated, antigen-reactive, CD4+T cells. Activated, irradiated, myelin basic protein (MBP)-specific T cells stimulate brisk proliferation when cultured with freshly isolated, autologous PBMC. Determination of the phenotype of the responding PBMC T cells revealed a prominent expansion of γδ T cells, principally of the Vγ2 subset. There was only minimal proliferation of PBMC following culture with irradiated, MBP-specific T cells that had not been recently activated. However, addition of rIL-2 to cultures of PBMC and nonstimulated MBP-specific T cells restored proliferation and the expansion of the γδ T cells. IL-2 alone did not mediate this effect. While MBP was a convenient antigen to use in these experiments, similar γδ T cell expansionin vitrowas noted using activated, CD4+T cells reactive with an exogenous antigen, Candida. In additional experiments, γδ-enriched T cell lines and certain Vγ2 T cell clones continued to respond to activated but not to nonstimulated, CD4+T cells. Overall, this study suggests that Vγ2 Vδ2 T cells may proliferate as a consequence of the activation of CD4+T cells. At least one ligand associated with T cell activation is required in addition to IL-2. |
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