Objective: To describe the immunohistochemical features of very early rheumatoid synovitis in disease modifying antirheumatic drug- and corticosteroid-naïve patients.
Methods: Eight patients presenting with oligoarthritis or polyarthritis, who later met American Rheumatism Association criteria for rheumatoid arthritis (RA), underwent needle synovial biopsies of a knee joint within the first 6 weeks after onset of disease symptoms. Using antibodies to CD3, CD8, L26, CD68, and von Willebrand factor, a detailed quantitative immunohistochemical analysis was done.
Results: CD3+ T lymphocytes, CD8+ T lymphocytes, L26+ B lymphocytes, and CD68+ macrophages were seen in 8/8 (100%), 7/8 (87%), 4/8 (50%), and 6/6 (100%) of synovial biopsies stained with the respective marker. There was a wide variation in number of positive cells between patients. CD3+ and CD8+ T cells were seen predominantly in perivascular areas, less often in a diffuse distribution, and not in aggregates. L26+ B lymphocytes were found in much smaller numbers compared with T lymphocytes. A mean of 67 vessels/mm2 was noted. No lymphoid aggregates were seen. In all cases, infiltration of macrophages and lymphocytes was limited mainly to relatively superficial parts of synovium, i.e., within 1 to 2 high power fields of the surface.
Conclusion: An absence of lymphoid aggregates or dramatic vascularity and a predominantly superficial infiltrate consisting mainly of perivascular T cells with few B cells characterized our patients with very early RA of < 6 weeks' duration. Thus, there appear to be some potentially important differences from findings reported in well established disease.