CD1-restricted microbial lipid antigen-specific recognition found in the CD8(+) alpha beta T cell pool

It is generally accepted that TCR alpha beta(+) CD8(+) T cells recognize im munogenic peptides bound to MHC-encoded class I molecules, This recognition is a major component of the cellular response mediating immune protection and recovery from viral infections and from certain intracellular bacterial infections, Here, we report two human CD8(+) TCR alpha beta(+) T cell line s specific for Mycobacterium tuberculosis Ags presented in the context of C D1a or CD1c Ag-presenting molecules. These T cells recognize lipid Ags and display cytotoxicity as well as strong Th cell type I cytokine responses. B y extending presentation by the CD1 system to the major TCR alpha beta(+) C D8(+) T cell pool, this system gains wider applicability beyond the double negative subset of T cells previously shown to have this reactivity, This i mplies that previous assumptions about the role of CDS' T cells in microbia l immunity may require revision as the relative proportions of CD1-restrict ed and MHC class I-restricted CD8(+) T cells are further defined.