Interleukin 17-Producing _γδ T Cells Increased in Patients with Active Pulmonary Tuberculosis

Abstract

Although it has been known that _γδ T cells may play an important role in the immune response to infection of Mycobacterium tuberculosis (M. tb), the mechanisms by which the _γδ T cells participate in the innate and/or acquired immunity to tuberculosis (TB) have not been full elucidated. In the present study, 27 patients with active pulmonary TB and 16 healthy donors (HD) were performed. We found that proportion of IL-17-producing cells among lymphocyte was similar between TB patients and HD, whereas the proportions of _γδ T cells in IL-17-producing cells (59.2%) and IL-17-producing cells in _γδ T cells (19.4%) in peripheral blood were markedly increased in TB patients when compared to those in HD (43.9% and 7.7%, respectively). In addition, the proportions of IFN-_γ-producing _γδ T cells in TB patients were obviously lower than that in HD. Upon re-stimulated with M. tb heat-treated antigen (M. tb-HAg) in vitro, fewer IL-17-producing _γδ T cells were generated from HD and TB patients, whereas IFN-_γ-producing _γδ T cells were increased in TB patients compared to that in HD. Our findings in TB patients and healthy human were consistent with other murine investigation that the IL-17-producing _γδ T cells were main source of IL-17 in mouse model of BCG infection, suggesting that _γδ T cells might be involved in the formation of tubercular granuloma in pulmonary TB patients, but need further identification.