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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.)

The course and outcome of rheumatoid arthritis is variable and often unpredictable. Many symptoms and characteristics of rheumatoid arthritis have been studied in an effort to better predict patients' outcomes. Histopathologic changes (disease-related cellular changes) may help to indicate worsening of disease, but have previously been thought to be difficult to study. However, good joint tissue samples were obtained from patients previously untreated for rheumatoid arthritis (RA), and results indicated that the course of the disease was reflected in levels of lymphocytes (immune system cells important in fighting infection). The presence of immune cells in synovial (joint) tissue from 57 patients with RA was studied and correlated with the disease course over three years. At the start of the study, the index of disease activity (IDA) correlated significantly with thickening of the synovial lining, infiltration by mononuclear (having one nucleus) immune cells, and the presence of T lymphocytes (T cells) containing a particular cell surface protein known as CD5. Patients were divided into two groups, one having milder disease during initial examinations, the other having more severe disease at that time. After one year, the IDA in patients with severe disease improved by 64 percent, while the other group improved by 13 percent. Synovial lining thickening correlated with medical status in the severe-disease group. After three years, synovial lining thickening correlated very significantly with medical status in patients with milder disease. Additionally in these patients, medical status correlated with levels of T cells that were positive for the CD5 protein. The report suggests that early lymphocyte infiltration may influence the course of RA, but the effects of disease-modifying drugs, usually used to treat more severe disease, on lymphocyte levels are unknown. (Consumer Summary produced by Reliance Medical Information, Inc.)