Gamma Delta T Cells
Human T cells recognize infectious agents or cancer through two main types of cell surface antigen receptors. CD4+ or CD8+ cells express alpha and beta chains to form the αβ T cell receptor (TCR). An alternate T cell receptor is made from gamma and delta chains (γδ TCR). The αβ TCR recognizes peptides presented by major histocompatibility complex (MHC) molecules. Molecular targets for γδ TCR include non-peptidic antigens that are recognized without MHC presentation. During early phases of HIV disease, the major subset of γδ T cells in blood is extensively depleted or inactivated. Consequently, HIV patients have profound γδ T cell deficiencies and fail to generate normal γδ T cell responses to phosphoantigens (five-carbon pyrophosphates made by the host or selected microbes). The phosphoantigen response is important for natural tumor immunity, for tuberculosis resistance, for immune regulation and probably for HIV control. Thus, γδ T cell depletion occurring in every infected...
KeywordsLymphoma Leukemia Tuberculosis Malaria Microbe
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