Altered signal transduction in SLE T cells.

T cells from patients with systemic lupus erythematosus display numerous signalling abnormalities. The T cell receptor complex is rewired with the common FcRgamma chain replacing the CD3 zeta chain while the T cell surface membrane lipid rafts are aggregated. These two aberrations result in enhanced early signalling events and altered downstream signalling events. These are in turn responsible for an altered expression of cytokines such as interleukin-6 (IL-6), IL-10, IL-2, IFNy and CD40 ligand. While some of these abnormalities explain the enhanced ability of T cells to help B cells to produce autoantibodies, decreased IL-2 production results in enhanced susceptibility to infections, reduced activation-induced cell death and prolonged survival of autoreactive T cells, which promote help to autoreactive B cells.