Lack of CD27- CD45RA -V γ9V δ2+ t cell effectors in immunocompromised hosts and during active pulmonary tuberculosis

In humans, the circulating pool of mycobacteria-reactive V γ9V δ2⁺ T cells is expanded with age and may contribute to Mycobacterium tuberculosis immunosurveillance. We observed that two subsets of V γ9V δ2⁺ T cells could be identified on the basis of CD27 expression in immunocompetent adults, showing that functionally differentiated γδ T cells have lost CD27 expression. In contrast, the CD27^-CD45RA ^-V γ9V δ2⁺ 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 V γ9V δ2⁺ T cell effectors were significantly reduced in patients with acute pulmonary tuberculosis, resulting in a reduced frequency of IFN-γ-producing cells after stimulation with nonpeptidic mycobacterial ligands. These observations indicate that monitoring and boosting γδ T cell effectors could be clinically relevant both in immunocompromised hosts and during active tuberculosis disease.