A longitudinal study of in vitro tests for lymphocyte function in rheumatoid arthritis.

In vitro tests of lymphocyte function have been performed in 61 patients with ;classical' or ;definite' rheumatoid arthritis. In vitro lymphocyte function was assessed by lymphocyte transformation responses to phytohaemagglutinin (PHA), Pokeweed mitogen (PWM), Candida antigen, and herpes simplex type I (HSV1). Follow up data were available after 6 months of treatment in 32 of these patients. Spontaneous lymphocyte transformation was assessed in all patients. Results obtained in patients with rheumatoid arthiritis were compared to those seen in a normal control population. Disease activity of patients with rheumatoid arthritis was assessed using standard clinical methods. Lymphocytes from patients with rheumatoid arthritis showed a similar degree of spontaneous transformation to that seen in normal subjects. In contrast, lymphocytes from patients with rheumatoid arthritis responded less well to PHA and Candida and HSV1 antigens when compared to normal patients. In patients with rheumatoid arthritis the response to PWM was markedly enhanced compared to normals. Clinical improvement was noted in 19 of the 32 patients seen at follow up, all of whom had received gold or penicillamine therapy. The abnormal responses of PHA and PWM seen before treatment became normal in those patients who improved clinically. The responses to Candida and HSV1 antigens not only returned to normal following treatment but were increased above those seen in normal controls. A statistically significant association was seen between clinical improvement and improvement of in vitro tests of lymphocyte function.