VARIATION IN H-2K(K) PEPTIDE MOTIF REVEALED BY SEQUENCING NATURALLY PROCESSED PEPTIDES FROM T-CELL HYBRIDOMA CLASS-I MOLECULES

Class I major histocompatibility complex (MHC) molecules interact with a diverse array of self and foreign peptides, displaying them on the cell surface and providing an extracellular indication of intracellula r invasion, The most clearly defined role for these class I/peptide co mplexes is to cause effector responses upon binding to antigen-specifi c receptors of cytotoxic T cells, We have characterized the mouse thym oma/rat V beta 8.2+ T-cell hybridoma C14/BW12-12A1 by fluorescence-act ivated cell sorting analysis and have used immunoaffinity chromatograp hy to purify class I molecules from these cells. The peptides bound to the class I molecules were fractionated by high-performance liquid ch romatography and sequenced. Self-peptide mixtures eluted from the mous e H-2K(k) class I allele revealed a dominant primary sequence moth, wi th a carboxyl-terminal residue that appeared to be invariantly valine and a secondary or auxiliary anchor residue at position 2 that could b e either glutamate or proline. The majority of naturally processed pep tide ligands appeared to be octamers, Although peptides eluted off H-2 K(k) molecules from tissue derived from a number of different inbred m ouse strains also appeared to be octamers, others have reported that i soleucine is the dominant carboxyl-terminal residue, Thus, different c ell types displayed distinct differences in naturally processed peptid es bound by the same class I alleles. The variation in naturally proce ssed peptides loaded onto the same class I allele most likely reflects the nature of the pool of peptides within the cell available for load ing class I molecules. (C) 1996 Wiley-Liss, Inc.