Lack of CD27-CD45RA-Vγ9Vδ2+ T cell effectors in immunocompromised hosts and during active pulmonary tuberculosis

In humans, the circulating pool of mycobacteria-reactive Vgamma9Vdelta2(+) T cells is expanded with age and may contribute to Myco-bacterium tuberculosis immunosurveillance. We observed that two subsets of Vgamma9Vdelta2(+) T cells could be identified on the basis of CD27 expression in immunocompetent adults, showing that functionally differentiated gammadelta T cells have lost CD27 expression. In contrast, the CD27(-)CD45RA(-)V(-)gamma9Vdelta2(+) T cell subset of effector cells was absent in cord blood cells from healthy newborns and lacking in the peripheral blood from HIV-infected patients. Moreover, circulating Vgamma9Vdelta2(+) T cell effectors were significantly reduced in patients with acute pulmonary tuberculosis, resulting in a reduced frequency of IFN-gamma-producing cells after stimulation with nonpeptidic mycobacterial ligands. These observations indicate that monitoring and boosting gammadelta T cell effectors could be clinically relevant both in immunocompromised hosts and during active tuberculosis disease.