SIGNIFICANCE OF ANTIBODIES TO STREPTOCOCCAL M-PROTEIN IN PSORIATIC-ARTHRITIS AND THEIR ASSOCIATION WITH HLA-A-ASTERISK-0207

Psoriatic arthritis (PA) is an immune disease associated with HLA-A2 i n the Japanese population. To investigate mechanisms the association b etween HLA-A2 and PA, we examined in vivo immune responsiveness to Str eptococcus pyogenes. Recombinant M proteins for the subtype specific N -terminal half (AB region) and conserved C-terminal half (C region) we re produced separately. IgG antibody level against each region was mea sured by ELISA in 31 PA patients, 88 patients with psoriasis vulgaris, 6 patients with rheumatoid arthritis and 77 healthy controls. We foun d that IgG antibody levels against the C region were markedly higher i n the PA patient group than in the other disease groups or controls. F urther, IgG antibody levels were higher in PA patients with spondyliti s and polyarticular arthritis than in PA patients with rheumatoid-like arthritis and arthritis mutilans. In contrast, no significant differe nce in the IgG antibody levels against the AB region was observed amon g the tested groups. HLA-A2 DNA typing showed that HLA-A0207 was asso ciated with PA (RR = 17.6; p(corr)<0.01) and the IgG antibody response s to the C region correlated well with the presence of HLA-A0207. The se results suggest that streptococcal infection may be involved in the pathogenesis of PA by participating in the HLA-linked immune responsi veness.