Immunohistological features of synovitis in ankylosing spondylitis: a comparison with rheumatoid arthritis.

The immunohistological features of the synovial membrane in ankylosing spondylitis, HLA-B27 associated oligoarthritis, and rheumatoid arthritis wer examined with particular reference to T lymphocyte subsets. T helper (CD4+) cells clearly outnumbered T suppressor/cytotoxic (CD8+) cells in rheumatoid arthritis, whereas both cell types were present in equal numbers in ankylosing spondylitis. A reduction of CD4+/CD45R+ suppressor/inducer cells relative to CD4+/UCHL1+ helper/inducer cells was apparent in all diagnostic groups. The observations were suggestive of disease specific inflammatory responses within synovial membrane.