Spontaneous recovery of the decreased expression in vitro of interleukin 2 receptors in rheumatoid arthritis.

Peripheral blood mononuclear cells (PBM) from 11 patients with rheumatoid arthritis (RA) stimulated with 0.13 and 0.25 microgram/ml phytohaemagglutinin (PHA) for 3 days showed a depressed expression of interleukin 2 receptor (IL-2R) when compared with 14 normal controls (P less than 0.01). At these two doses of PHA a depressed lymphocyte proliferative response was also observed (P less than 0.01). However the kinetics of the response of the RA group differed from those of the control group. Whereas by day 6 IL-2R expression and lymphocyte proliferation in the control group was decreased compared with day 3, responses of the RA cells were increased. Following stimulation with the higher dose of PHA (1 microgram/ml) the kinetics of lymphocyte proliferation and IL-2R expression were equivalent in control and RA cultures. These results demonstrate that the impaired IL-2R expression and lymphocyte proliferation observed with sub-optimally stimulated PBM from RA patients is spontaneously reversed during prolonged culture and is consistent with the hypothesis that there is a lack of available IL-2 in the early stages of culture.