Interleukin 2 deficiencies in rheumatoid arthritis and systemic lupus erythematosus.

The ability of peripheral blood lymphocytes from patients with systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and Sjogren's syndrome (SS) to produce interleukin 2 (IL-2) and respond to it in-vitro was examined. Phytohemagglutinin-stimulated lymphocytes from over half of the SLE patients exhibited a decreased ability to produce IL-2 while their concanavalin A-generated blast cells responded normally to exogenous IL-2. Lymphocytes from RA patients not only produced less IL-2 than normals (P less than 0.001), but also responded poorly to exogenous IL-2 (P = 0.011). These abnormalities did not correlate with the patient's age, sex, duration of disease, or disease activity. Production of and response to IL-2 was widely varied among patients with SS and not different from controls. The decreased response of RA lymphocytes to IL-2 may result from a smaller number of cell surface IL-2 receptors since IL-2 adsorption to RA cells was lower than to either SLE or normal cells. These data suggest that IL-2-related abnormalities may play a role in the disordered immunoregulation characteristic of RA and perhaps of SLE.