T-lymphocyte subpopulations in rheumatoid arthritis.

We studied 24 patients with rheumatoid arthritis and 24 age- and sex-matched controls for lymphocyte subpopulations in the peripheral blood. Patients with rheumatoid arthritis had a significantly lower relative lymphocyte count (p < 0.005) and a higher percentage of T lymphocytes bearing Fc-receptor for IgM (TM) (p < 0.05). The proportion of B lymphocytes, total T lymphocytes and T lymphocytes with Fc-receptors for IgG (TG) in patients with rheumatoid arthritis was not different from that in controls. In 1 of 5 cases tested incubation of T lymphocytes in autologous rheumatoid factor positive serum instead of FCS resulted in significant reduction of TM and increase in TG cells. These results are discussed in relation to possible immunological factors involved in the etiology of rheumatoid arthritis.