Human gamma delta T-cell recognition of Yersinia enterocolitica

We have studied the human gamma delta T-cell response to Yersinia enterocolitica, a facultative intracellular bacterium which causes gastroenteritis and, particularly in human leucocyte antigen (HLA)-B27+ individuals, reactive arthritis (ReA). A marked proliferation of that cytotoxic gamma delta T cells is seen when Yersinia-infected lymphoblastoid cell lines or fixed intact Yersinia are added to cultures of mononuclear cells derived from the synovial fluid of ReA patients or from the peripheral blood of healthy donors. In contrast, heat-inactivated Yersinia fail to stimulate the gamma delta T-cell response. The gamma delta T-cell lines generated killed both autologous and allogeneic infected cell lines. Interestingly, a T-cell line generated from synovial fluid mononuclear cells (SFMC) killed infected autologous cell lines and a cell line matched for HLA-B27 less well than infected allogeneic target cells. gamma delta T-cell clones isolated from this line were found to express V gamma 9V delta 2 T-cell receptor (TCR) and also killed infected mismatched cells more efficiently than autologous targets. Moreover, from experiments using major histocompatability complex (MHC)-deficient cell lines, it was apparent that target cell recognition was MHC independent. Our results suggest that gamma delta T cells can be involved in immunity to Yersinia enterocolitica and should be taken into account when considering immunopathological mechanisms leading to reactive arthritis.