FAS and tuberculosis: In present study, we observed that a high lesion severity score was correlated with a decreased Vδ2+ T cell number and increased Vγ2Vδ2 T cells Fas/FasL expression leve in the peripheral blood, a phenomenon that was consistent with a previous study by Pinheiro et al., who found that the reduction of peripheral γδ T cell is closely associated with higher lesion severity in tuberculosis patients [42].