HL‐A 27 in reactive arthritis. A study of yersinia arthritis and Reiter's disease

The histocompatibility antigen HL‐A 27 was identified in 43 of 49 patients with yersinia arthritis and in 36 of 40 patients with Reiter's disease, compared with 3 of 20 patients with yersinia infection without arthritis and 14% of the normal Finnish population. HL‐A 2 occurred in patients with reactive arthritis in the same high frequency as did HL‐A 27, but this antigen is present in 55% of Finns. HL‐A 27 negative patients usually had a mild or somewhat atypical disease.