Rheumatoid Arthritis: Ultrastructure of the Synovium

Excerpt

Several lines of investigation have recently focused attention on the ultrastructure of the synovium in rheumatoid arthritis. Electron microscopy has shown that a significant proportion of the synovial lining cells correspond to macrophages in both cytologic organization and phagocytic potential (1, 2). These cells, sometimes designated type A or type M, undergo a pronounced hyperplasia in rheumatoid arthritis and display intense acid phosphatase activity. Multinucleated giant cells of macrophage (type A cell) origin also occur with some frequency (3) and contain similar hydrolytic enzyme.

Current thinking about the nature of rheumatoid arthritis is dominated by a concern with hypersensitivity mechanisms,