HLA-B27 in rheumatoid arthritis and amyloidosis.

To study the role of genetically determined immune responsiveness in the pathogenesis of systemic amyloidosis complicating rheumatoid arthritis the HLA antigens were identified in 26 patients with rheumatoid arthritis complicated by secondary amyloidosis, in 44 patients with rheumatoid arthritis, and in 11 patients with secondary amyloidosis of non-rheumatoid origin. Subjects with ankylosing spondylitis, sacroiliitis without peripheral polyarthritis, Reiter's disease, reactive arthritis, erosive osteoarthritis, psoriatic arthropathy, systemic lupus erythematosus or arthritis associated with a gastrointestinal involvement were excluded from the study. Patients with amyloidosis secondary to rheumatoid arthritis had a high frequency of the HLA specificity B27 and of the haplotype likely to bear A2, B27. The association with B27 was closest in the group of male patients with amyloidosis whose rheumatoid arthritis had begun at an early age and who lacked demonstrable rheumatoid factor in serum. These patients may represent a genetically determined subentity of rheumatoid arthritis.