Delineation of the function of a major γδ T cell subset during infection

gamma delta 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 gamma delta T cells. Using mice deficient in V gamma 1(+) T cells which are a major component of the gamma delta T cell response to microbial infection, a specific immunoregulatory role for V gamma 1(+) T cells in macrophage and gamma delta T cell homeostasis during infection has been established. By contrast, V gamma 1(+) T cells play no significant role in pathogen containment or eradication and cannot protect mice from immune-mediated pathology. Pathogen-elicited V gamma 1(+) T cells also display different functional characteristics at different stages of the host response to infection that involves unique and different populations of V gamma 1(+) T cells. These findings, therefore, identify distinct and nonoverlapping roles for gamma delta T cell subsets in infection and establish the complexity and adaptability of a single population of gamma delta T cells in the host response to infection that is not predetermined, but is, instead, shaped by environmental factors.