T cells recognize antigenic peptides presented on the cell surface by
major histocompatibility complex (MHC) molecules. Here, Roman Chicz an
d Robert Urban describe the features of peptides bound to MHC molecule
s and the mechanism by which these surface proteins bind diverse pepti
de ligands with high affinity. In addition, they discuss the applicati
on of new technologies to the identification of MHC-associated peptide
s.