Adaptive immune response of Vγ2Vδ[2.sup.+] T cells during mycobacterial infections

To examine the role of T cell receptor (TCR) in γδ T cells in adaptive immunity, a macaque model was used to follow Vγ2Vδ[2.sup.+] T cells responses to mycobacterial infections. These phosphoantigen-specific γδ T cells displayed major expansion during Mycobacterium bovis Bacille Calmette-Guerin (BCG) infection and a clear memory-type response after BCG reinfection. Primary and recall expansions of Vγ2Vδ[2.sup.+] T cells were also seen during Mycobacterium tuberculosis infection of naive and BCG-vaccinated macaques, respectively. This capacity to rapidly expand coincided with a clearance of BCG bacteremia and immunity to fatal tuberculosis in BCG-vaccinated macaques. Thus, Vγ2Vδ[2.sup.+] T cells may contribute to adaptive immunity to mycobacterial infections.