HL-A antigens in juvenile rheumatoid arthritis.

HL-A antigens were examined in sixty-two patients, thirty-one boys and thirty-one girls, diagnosed as having JRA. HL-A 27 was the only antigen with a significantly increased frequency. This increase concerned predominantly male patients in whom the disease developed at the beginning of puberty. In this group of sixteen boys, the polyarticular form was more frequent and tended to be associated with sacroliitis, while the rheumatoid factor was negative in all but one. The frequency of HL-A 27 in this group was 65.5%. The patients were also examined by the lymphotoxic test with anti H-2 alloimmune sera known to exhibit a high degree of association with some HL-A antigens. On JRA lymphocytes these associations were confirmed for HL-A 2 and anti-H-2f and for HL-A 27 and anti-H-2p. The strongest reactions were observed with lymphocytes from male patients around the age of puberty. These data indicate that steroid hormones influence the expressivity of some HL-A associated cell plasma membrane structures.