Do lymphocytes protect the rheumatoid joint?

The pathology of the synovial membrane in rheumatoid arthritis can be characterized by the prominence of two major features which appear to vary independently of one another. These are synovial lining-cell proliferation and infiltration with inflammatory cells, predominantly lymphocytes. In a series of 42 synovectomies from 36 patients it has been shown that extensive joint damage is associated with a synovial picture of marked lining-cell proliferation and a sparsity of lymphocytes. Cases with heavy lymphocyte infiltration tend to show less damage to articular cartilage and bone despite a similar duration of disease. These results have been compared with the picture in leprosy, where a similar pathological spectrum is associated with changes in cell-mediated immunity necessary for the control of infection.