[Histocompatibility antigens in psoriatic and seronegative rheumatoid arthritis].

Antigens of A and B loci of the histocompatibility system were investigated in 173 patients: 35 with psoriatic arthritis, 38 with seronegative rheumatoid arthritis, 80 with seropositive rheumatoid arthritis and 20 with uncomplicated psoriasis. The results of typification showed that B13 antigen was common in every other patient with uncomplicated psoriasis or psoriatic arthritis, and in the patients with seronegative rheumatoid arthritis it was much more common than in the patients with seropositive rheumatoid arthritis or in the population. Proceeding from the authors' and literature data it was assumed that as a matter of fact, part of the patients (about 15%) with seronegative rheumatoid arthritis had rheumatoid-like psoriatic arthritis without skin manifestations.