COMPARISON OF PEPTIDES FLUTED FROM THE GROOVE OF HLA-B27 FROM SALMONELLA INFECTED AND NONINFECTED CELLS

Reactive arthritis (ReA) is associated with the MHC class-I molecule H LA-B27 and caused by certain Gram-negative bacteria. The mechanism by which HLA-B27 confers a higher susceptibility for this disease compare d to other MHC Class-I alleles is still not known. We investigated whe ther infection of human HLA-B27(+) cells is able to change the peptide repertoire presented by these HLA-B27 molecules. To this end large qu antities of a B-cell line (C1R-B27) transfected with HLA-B2705 mere in fected with S.typhimurium. Peptides were eluted from the B27 molecules and separated by Reversed Phase Chromatography (RPC). We then compare d the peptide profiles obtained from S.typhimurium infected C1R B-cell s with that obtained from non infected cells, Apart from a few additio nal peaks present in the profile derived from the infected batch the p eptide profiles were almost identical. A few fractions were subjected to sequencing by Edman degradation. All peptides found were nonameres with arginine (Arg) at position 2 which is in agreement with the previ ously described HLA-B27 peptide binding motif. The majority of peaks e xpressed a mixture of at least four different peptides. The analysis o f differences between HLA-B27 bound peptides from Salmonella infected and non infected cells might lead to the identification of T-cell epit opes shared by Salmonella and autoantigens.