Different HLA-D associations in adult and juvenile rheumatoid arthritis.

HLA-D typing was performed in 126 patients with juvenile rheumatoid arthritis. HLA-DW4, the antigen found in previous studies to characterize adult rheumatoid arthritis, had a significantly lower frequency in children with arthritis than in normal controls (P less than 0.04). By contrast, in children the antigens HLA-DW7 (P less than 0.03) and HLA-DW8 (P less than 0.01) were increased compared to controls. The antigen TMo, detected with homozygous typing cells from a child with juvenile rheumatoid arthritis, was found to be related to the cross-reactive specificities HLA-DW7 and DW11. 46% of the patients with persistent pauciarticular arthritis of childhood typed for the antigen TMo, compared to only 1% of normal controls. Thus the relative risk for persistent pauciarticular arthritis in relation to the presence of TMo was 67.7 (P less than 0.0001). These results provide evidence of fundamental differences between adult rheumatoid arthritis and arthritis of childhood. The latter group appears to include a population distinguishable clinically and characterized in these studies by the HLA-D determinant TMo.