ENDOGENOUS PEPTIDES BOUND TO THE HLA-A2 MOLECULES EXPRESSED BY A STOMACH-CANCER CELL-LINE

Analysis of the gene products of the HLA-A locus by cDNA sequencing sh owed that cultured stomach carcinoma (KATO-III) cells and cultured B-l ymphoblastoid (TAB089) cells express HLA-A0201/0207 allospecificities . In order to determine whether these two cell lines express distinctl y different major histocompatibility complex (MHC)-bound endogenous pe ptides, the HLA-A2-bound peptides were eluted by acid treatment and an alyzed using high-performance liquid chromatography. Comparison of the elution profiles of the peptides eluted from the two cell lines showe d that 1) most peptide peaks were common to both cell lines, 2) two pe aks were detected only from KATO-III cells and 3) six peaks were detec ted only from TAB089 cells. These results indicate that the stomach ca ncer cell line KATO-III and the B-lymphoblastoid cell line TAB089 expr ess distinctly different HLA-A2-bound endogenous peptides. Peptide seq uencing of the two KATO-III-specific peaks indicated that they had anc hor amino acids (leucine and valine) corresponding to the known peptid e-motif for HLA-A2 antigens, although two different amino acids were f ound at several positions, indicating that both peaks contained two di fferent peptides.