News Release

GammaDelta T cells in innate anti-bacterial defenses

Peer-Reviewed Publication

JCI Journals

Innate immune responses, by definition, exist prior to infection and do not involve immunological memory. For this reason, innate responses are useful for host defense soon after initial exposure to an infectious agent, which must be kept at bay, at least until a specific response can be mounted. Such innate responses, including phagocytosis of infectious agents and their destruction by endogenous antibiotic substances, are generally contrasted with the clonal immune system of B and T cells, However, certain branches of the clonal system show intrinsic specificity for bacteria, as in the case of some natural antibodies that arise from non-recombined Ig gene segments. Wang et al. have now identified a counterpart of these B cells in the cellular immune system. T cells bearing the gd receptor type g2d2 are sufficient to control infections with either of 2 different gram-negative bacteria in mice that otherwise lack B or T cells. g2d2 T cells represent a small but significant fraction of T cells in the peripheral blood of healthy animals. Although exposure to bacterial metabolites can dramatically increase their representation, even at their initial low level they afford the host substantial protection from septic infections. Such cells become activated by exposure to any of several bacterial metabolites that accumulates in infected tissues, and they secrete g-interferon in response, which directly stimulates circulating monocytes to clear the infection.

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