[Analysis of naturally processed peptides bound to HLA-DR4, DR53 (DRB1*0405, DRB4*0101)]

We have isolated peptides bound to HLA-DR4, DR53 molecules obtained from HLA homozygous cell line cells, EBV-Wa (DRB1*0405, DRB4*0101), and determined amino acid sequences of the peptides. Amino acid sequences of 19 peptides were obtained and identified as peptide fragments of known proteins. Of those, macrophage migration inhibitory factor (MIF), beta 2 microglobulin (beta 2m), pyruvate kinase M2 (PKM2) and cathepsin C are considered to be endogenously derived, while transferrin and apolipoprotein B-100 are exogenous proteins. Peptides corresponding to each protein have a shared sequence with amino terminal or carboxy terminal protrusions. Based on the core sequences, putative DR4, DR53-binding motifs were suggested as Y----T/V--D or Y----T--D.