Different lymphocyte populations in rheumatoid arthritis and their relationship to anti-Ig activities

The anti-immunoglobulin activities of rheumatoid arthritis appear to be related not only to plasma cells and their precursors, the B-lymphocytes. Evidence for interaction of IgG with T-lymphocytes and with Fc-bearing lymphocyte-like cells has now appeared. Both these cell types can mediate cytotoxicity which may also induce inflammation in addition to that provoked by rheumatoid factors and immune complexes. Rheumatoid factors and immune complexes may act primarily through the complement system. However, active inflammation in rheumatoid patients can occur without abundant immune complexes, e.g. in B-cell-deficient patients (31). In some cases this may be due to activation of the alternate complement pathway. However, the T-cell system with its series of lymphokines may also play an active part-in the inflammatory process. And both T-lymphocytes and Fc-bearing lymphocyte-like cells, the K-cells, can mediate cytotoxicity. Also in such patients further studies are needed to work out the complex interactions between these cell types and to discover the underlying cause or agent in the chronic destructive rheumatoid inflammation.