Characterization of a cytotoxic CD57+ T cell subset from patients with pulmonary tuberculosis

We investigated the proportion, phenotype, and cytotoxicity of CD8+CD57+ and CD57− T cells in peripheral blood from 20 tuberculosis (TB)-patients and 20 healthy tuberculin skin test-positive donors. Our results showed an increase in CD8+CD57+ T cells from TB-patients as compared with those from age-matched healthy donors (p < 0.0001). CD8+CD57+ T cells from TB-patients expressed CD69, perforin, granzyme-A, and a CD28−CD62L−CD161− phenotype without recognition for the alpha-galactosylceramide–CD1d complex. This cell subset also expressed TNF-α and IFN-γ, under phorbol-myristate-acetate/ionomycin stimulation. Interestingly, the cytotoxicity against autologous monocytes was higher in CD57− cells from TB-patients and donors than their CD57+ counterparts, in the presence of Mycobacterium tuberculosis H37Rv culture filtrate. However, only CD8+CD57+ T cells from TB-patients exhibited spontaneous cytotoxicity against monocytes in the absence of antigen. Our results suggest that CD8+CD57+ T cells are a subset of effector cells that could be helpful to evaluate the cell-mediated immune response to M. tuberculosis.