Interleukin 17-producing γδ T cells increased in patients with active pulmonary tuberculosis

Although it has been known that gamma delta T cells may play an important role in the immune response to infection of Mycobacterium tuberculosis (M. tb), the mechanisms by which the gamma delta 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 gamma delta T cells in IL-17-producing cells (59.2%) and IL-17-producing cells in gamma delta 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-gamma-producing gamma delta 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 gamma delta T cells were generated from HD and TB patients, whereas IFN-gamma-producing gamma delta 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 gamma delta T cells were main source of IL-17 in mouse model of BCG infection, suggesting that gamma delta T cells might be involved in the formation of tubercular granuloma in pulmonary TB patients, but need further identification.