Seshadri, ChetanJames, Charlotte A2020-08-142020-08-142020James_washington_0250E_21490.pdfhttp://hdl.handle.net/1773/46145Thesis (Ph.D.)--University of Washington, 2020Tuberculosis (TB) is of high global health importance and disproportionately affects individuals in resource-limited settings. A major challenge to reducing the global burden of this disease is the lack of effective vaccines and diagnostics. At present, the intricacies of the immune response to this disease are not understood well enough to rationally develop efficacious vaccines. Peptide-specific T cells have been implicated as a critical component of the immune response to TB. However, there are few studies that investigate the role of T cells that recognize non-peptide antigens in the immune response to TB. T cells can recognize lipid antigens presented by CD1 molecules, but how these antigens are recognized and the impact that antigen recognition has on lipid-specific T cell activation and functional differentiation is not understood. Here, we elucidate the molecular and cellular factors that affect lipid antigen recognition by human T cells, and what impact these factors have on T cell activation and function. This work focused on a family of mycobacterial lipids, diacylated sulfoglycolipids (Ac2SGL), which are only expressed by virulent strains of Mycobacterium tuberculosis, the causative agent of TB. The first aim of this work utilized synthetic Ac2SGL analogs, a panel of T cell clones, and antigen presenting cells that express mutated CD1 molecules to probe the specificity with which these antigens are recognized by T cells to inform which molecular moieties are essential for Ac2SGL recognition by T cells. The second aim investigated the impact of T cell receptor co-receptors on antigen recognition at the cellular level, as this influences the magnitude of activation and functional differentiation of T cells. We found that co-receptors augmented T cell affinity for Ac2SGL and these molecules impact T cell function in vitro and ex vivo. Together, our data support an emerging model that related but chemically distinct antigens and T cell subpopulations should be studied independently to fully understand the T cell response to mycobacterial lipid antigens. As Ac2SGL holds promise as a target for novel vaccination and diagnostic strategies for TB, these studies will inform the development of tools to address these two major needs.application/pdfen-USnoneCD1GlycolipidLipid AntigenMycobacteriaT cellTuberculosisImmunologyPathologyThesis