| Research Abstract |
T cells recognize nominal antigens in the context of self-MHC antigens by T cell receptor(TcR) which is composed of alpha and beta chains. Another type of TcR, which is composed of gamma and delta chains has also identified. At least a significant fraction of gamma/delta T cells are reported to be specialized to recognize epitopes on mycobacterial antigens, suggesting that the gamma/delta bearing T cells may participate in immune surveillance against invasion with the various pathogens.
To elucidate a potential role of the gamma/delta T cells in host-defense against bacterial infection,we examined the kinetics of gamma/delta T cells and their ligands during intraperitoneal infections with Listeria monocytogenes, Salmonella chorelaesuis and BCG.
During infection with such intracellular bacteria, TcR gamma/delta T cells specific for 65kd hsp precede TcR alpha/beta T cells specific for bacterial antigens in appearance. The gamma/delta T cells provide a first line of defense against the infection by recognizing exogenous and endogenous 65 kd hsp on infected cells and producing cytokines such as gammaIFN. Our results suggest that the hsp- specific gamma/delta T cells respond quickly to antigenically diverse pathogens before antigen-specific alpha/beta T cells expand clonally, and they play a role in covering the gap between the phagocytic system and highly evolved immune response mediated by alpha/beta T cells.
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