B-CELL HYPERACTIVITY IS A FUNCTION OF T-CELL DERIVED CYTOKINES IN SYSTEMIC LUPUS-ERYTHEMATOSUS

Objective. T cell abnormalities and abnormal production of cytokines i s a key event of B cell hyperactivity and antibody synthesis in system ic lupus erythematosus (SLE). We investigated T cell function and role of interleukin 4 (IL4) and IL-6 in B cell induced Ig synthesis from S LE. Methods. Phenotypes and expression of activation antigens on T cel ls and monocytes was determined by specific monoclonal antibodies usin g indirect immunofluorescence technique. IL-4, IL-6 and tumor necrosis factor-alpha (TNF alpha) assays and in vitro Ig synthesis was carried out by enzyme linked immunosorbent assays. Results. CD25, CD38 and CD 71 expressing T cells and monocytes were increased in circulation of p atients with SLE. Patients with SLE associated with prominent clinical presentation like lymphadenopathy had a higher percentage of gamma de lta T cells in blood. CD4 + CD29 + T cell subsets, which were the majo r T cells secreting IL-6, were increased in the circulation and provid e effective helper function to B cells in their enhanced in vitro Ig s ynthesis in SLE. Conclusion. Our results demonstrate that CD4+CD29+ T cell subsets produced elevated levels of IL-6 in SLE and that IL-6 ove rproduction may contribute to the B cell hyperactivity in enhanced ant ibody synthesis characteristic of this autoimmune disease.