Impaired nonrestricted cytolytic activity in systemic lupus erythematosus

Abstract

AbstractObjective. To determine the cytolytic effector pathway involved in impaired generation of nonrestricted cytolytic activity in systemic lupus erythematosus (SLE).Methods. Peripheral blood mononuclear cells (PBMC) from normal subjects and SLE patients were stimulated in vitro with anti‐CD3 monoclonal antibody (MAb) and interleukin‐2 to promote the generation of nonrestricted cytolytic activity. On day 13 of culture, the PBMC were assayed for cytolytic activity against Fas‐Daudi cells and Fas+ Jurkat cells. The effects on cytotoxicity of calcium chelation, antagonist anti‐Fas MAb, tumor necrosis factor (TNF) α and β, and ATP were measured. Intracellular perforin expression was determined by intracellular staining, and perforin messenger RNA levels were determined by quantitative competitive reverse transcription‐polymerase chain reaction.Results. We demonstrated the existence of a cytolytic pathway that is independent of Fas, TNFα, TNFβ, and ATP, but is dependent upon extracellular calcium. Despite its calcium dependence, this pathway is associated with low‐to‐undetectable levels of perforin.Conclusion. Impaired generation of nonrestricted cytolytic activity in SLE is likely due to decreased activity of this Fas‐, TNFα‐, TNFβ‐, ATP‐independent pathway associated with very low levels of perforin.