Multiple class I motifs revealed by sequencing naturally processed peptides eluted from rat T cell MHC molecules

Abstract

Class I major histocompatibility complex (MHC) molecules interact with a diverse array of self and foreign peptides. Displayed on the cell surface, the class I/peptide complex provides an extracellular indication of the intracellular milieu. We have characterized the Lewis rat Vbeta8.2+ T cell hybridoma C14/BW12-12A1 by FACS analysis and have used immunoaffinity chromatography to purify class I molecules from these cells. Peptides eluted from the class I molecules have been fractionated by HPLC and sequenced. Self-peptide mixtures indicate two distinct peptide motifs, suggesting the possibility of multiple class I loci. The majority of the naturally processed peptide ligands were nonamers. Naturally processed peptide ligands fitting the first motif contained a hydrophobic leucine anchor residue at position three and a carboxyl-terminal serine anchor residue. A second motif was characterized by a tyrosine or phenylalanine residue at position three and a phenylalanine or isoleucine carboxyl-terminal residue. Four peptides derived from the Vbeta8.2 T cell receptor have sequences that fit these motifs, providing a mechanistic explanation for their immunoregulatory role. Identification of these class I peptide binding motifs will be useful for predicting potential CTL epitopes in studies on autoimmunity, immunoregulation and transplantation in the Lewis rat.

Strategic Manipulation of Tumor Antigens to Enhance Immunogenicity

“…Recent studies have elucidated the binding motif for Lewis/F344 strain rats (21). The peptide ligands are nonamers that contain a hydrophobic leucine anchor residue at position 3 and a carboxyl-terminal serine anchor residue.…”

“…These studies, however, would only be effective if an MHC class I-restricted peptide could be identified that elicited a cytolytic T cell response and was expressed on the tumor cells. Recent studies have identified the binding motif for MHC class I molecules in F344 rats (21). Based on computer modeling, six potential MHC class I binding peptide candidates were identified.…”

Effects of vaccination with T cell receptor peptides: Epitope switching to a possible disease‐protective determinant of myelin basic protein that is cross‐reactive with a TCR BV peptide

“…Recently, we characterized both rat and mouse MHC class I bound peptides eluted from rat‐mouse hybridomas obtained by fusing Gp‐MBP‐72–89‐specific T cells with the mouse BW‐5147 fusion partner 19 , 20 . From these eluted peptides, we identified two distinct nonamer peptide motifs, including XX L XXXXX S (pattern 1) and XX Y XXXXX F (pattern 2), thought to represent general patterns found in peptides that preferentially bind to two different RT‐1B MHC class I molecules 20 . Interestingly, the BV8S2‐42–50 peptide, HG L RLIHY S , contained MHC binding anchor residues identical to those found in pattern 1.…”