[Cross reactions of HLA A and B antigens in 63 patients with rheumatoid arthritis].

Cross reactions are very frequently observed when HLA A and B antigens are determined by a routine lymphocytotoxicity method. Such cross reactions are probably due to biochemical structural similarities shared by several HLA antigens. In this work, we studied the cross reactions which occurred during HLA A and B typing of 63 patients with classical or definite rheumatoid arthritis (RA) according to the ARA criteria. No association was found between RA and any single HLA A or B antigen. In contrast, when cross reactions were taken into account, the B8 B14 cross reactant group frequency was increased in RA patients (34,9 p. cent) as compared to controls (20 p. cent, p less than 0,004) and was even more clearly elevated in the 42 seropositive RA patients (40,5 p. cent, p less than 0,002). No relation was found between HLA phenotype and Sjögren's syndrome even when cross reactions were considered. The B8 DR3 haplotype has been shown to be associated with drug intolerance . The B8 B14 cross reactant group was present in 22 out of our 63 RA patients, 16 of whom were B8+. Among the latter, 6 patients exhibited poor tolerance to gold salts and 6 other patients did not respond to gold therapy, suggesting that the B8 antigen could predict not only a poor tolerance but also a poor response to disease modifying drugs.