HL-A27 and arthritis.

In patients with recent inflammatory arthritis HL-A27 was seen in 6 out of 7 patients with ankylosing spondylitis, in 15 out of 18 patients with Reiter's disease, in 9 out of 12 patients with reactive postinfectious arthritis, in 22 out of 45 patients with rheumatoid arthritis, and in 2 out of 14 patients with other types of inflammatory arthritis. In two control series HL-A27 occurred in 46 out of 326 persons and in 3 out of 34 persons. The high frequency of HL-A27 in RA patients is in disagreement with previous results by other investigators. The explanation for this may be either that the diagnostic criteria do not apply at the early stage of the disease, or that there is a high prevalence of HL-A27 associated RA in Finland.