Soluble interleukin 2 receptor levels in serum and its relationship to T cell abnormality and clinical manifestations of the disease in patients with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is associated with alterations in immune regulation that results in T cell activation and release of the soluble interleukin 2 receptors (sIL-2R) in serum. SLE, a disease with varied clinical manifestations also has regulatory T cell subset abnormalities in blood. Levels of sIL-2R in serum of patients with active SLE were higher than in those with other common rheumatic diseases. Patients with active SLE and an increased percentage of CD4+ CDw29+ helper inducer (memory) and decreased percentage of CD4+ CD45R+ suppressor inducer (virgin) T cell subsets in blood demonstrated elevated levels of sIL-2R in serum. When compared with clinical manifestations of the disease, the sIL-2R levels in the sera of the patients with active SLE and thrombocytopenia were higher (mean 1710 units/ml) than those in active SLE with nephrotic syndrome (mean 1230 units/ml) or in active SLE with central nervous system disease (mean 1157 units/ml). However, patients with active SLE with humoral immunodeficiency (hypogammaglobulinemia) had highly elevated levels of sIL-2R in serum as compared to other patients with active SLE. The highly elevated levels of sIL-2R in serum may indicate that in vivo T cell activation plays an important role in this disease.