Morphometric analysis of blood vessels in synovial membranes obtained from clinically affected and unaffected knee joints of patients with rheumatoid arthritis

A variety of cellular changes are associated with the synovitis (joint inflammation) of rheumatoid arthritis. These include thickening of the synovial lining, infiltration by immune cells, and proliferation of venules and capillaries (small blood vessels). This vascular proliferation may determine the rate of disease progression, probably by allowing migration of lymphocytes (immune cells usually associated with inflammation) into synovial tissue. The vessels are lined with tall endothelial cells similar to those normally found in healthy lymphoid tissues. Indices of vessel proliferation and endothelial cell tallness were evaluated in samples from 9 inflamed knees and 4 uninflamed knees of patients with untreated rheumatoid arthritis, and similar samples from 13 normal control autopsied subjects. Thickening of the synovial lining was observed in about two-thirds of the samples. Cell infiltration was found in about one-third of the samples. The level of blood vessels was significantly higher in inflamed knee joints than in normal knees, but not significantly different between inflamed and uninflamed arthritic knees. Levels of high endothelial-containing venules was highest in the inflamed knee joints, somewhat less in uninflamed arthritic knees (but not significantly so), and significantly less in the control knee samples. The report suggests that synovial lining thickening and cell infiltration can occur without medically apparent synovitis and is apparently not dependent on changes in synovial blood vessels. (Consumer Summary produced by Reliance Medical Information, Inc.)