The elucidation of T-cell antigens is crucial to the understanding of the molecular etiology of immune related disorders and the development of novel therapeutic strategies. Reliable identification of T-cell antigens would, in particular, address an unmet need in the fields of cancer immunology [1], autoimmunity [2] and infectious disease [3]. T-cell epitopes are short peptides displayed at the surface of antigen-presenting cells by the membrane-bound major histocompatibility complex (MHC) proteins, which are categorized as either class I or II. Class I molecules are expressed on the surface of nearly every cell of the body and present a sampling of short (8–14 residue [4]) peptides derived from proteolytic turnover
of proteins of both endogenous and exogenous origin. These MHC class I antigens are targets of direct attack from cytotoxic T-lymphocytes. MHC class II exists on the surface of professional antigen-presenting cells (pAPCs) and is responsible for priming naïve T-lymphocytes in peripheral lymphoid tissue.