Delineation of the function of a major gamma delta T cell subset during infection.

γδ T cells play important but poorly defined roles in pathogen-induced immune responses and in preventing chronic inflammation and pathology. A major obstacle to defining their function is establishing the degree of functional redundancy and heterogeneity among γδ T cells. Using mice deficient in Vγ1 + T cells which are a major component of the γδ T cell response to microbial infection, a specific immunoregulatory role for Vγ1 + T cells in macrophage and γδ T cell homeostasis during infection has been established. By contrast, Vγ1 + T cells play no significant role in pathogen containment or eradication and cannot protect mice from immune-mediated pathology. Pathogen-elicited Vγ1 + T cells also display different functional characteristics at different stages of the host response to infection that involves unique and different populations of Vγ1 + T cells. These findings, therefore, identify distinct and nonoverlapping roles for γδ T cell subsets in infection and establish the complexity and adaptability of a single population of γδ T cells in the host response to infection that is not predetermined, but is, instead, shaped by environmental factors.