B cell hyperactivity is a function of T cell derived cytokines in systemic lupus erythematosus.

Abstract

T cell abnormalities and abnormal production of cytokines is a key event of B cell hyperactivity and antibody synthesis in systemic lupus erythematosus (SLE). We investigated T cell function and role of interleukin 4 (IL-4) and IL-6 in B cell induced Ig synthesis from SLE. Phenotypes and expression of activation antigens on T cells and monocytes was determined by specific monoclonal antibodies using 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. CD25, CD38 and CD71 expressing T cells and monocytes were increased in circulation of patients with SLE. Patients with SLE associated with prominent clinical presentation like lymphadenopathy had a higher percentage of gamma delta T cells in blood. CD4+CD29+ T cell subsets, which were the major T cells secreting IL-6, were increased in the circulation and provide effective helper function to B cells in their enhanced in vitro Ig synthesis in SLE. Our results demonstrate that CD4+CD29+ T cell subsets produced elevated levels of IL-6 in SLE and that IL-6 overproduction may contribute to the B cell hyperactivity in enhanced antibody synthesis characteristic of this autoimmune disease.