Autoantigen‐induced IL‐13 mRNA expression is increased in blood mononuclear cells in myasthenia gravis and multiple sclerosis

Abstract

Evidence has been presented for the involvement of immune mechanisms in the pathogenesis of myasthenia gravis (MG) and multiple sclerosis (MS). The production of autoantibodies in both diseases is regulated by T‐cells by means of cytokines. Interleukin‐13 (IL‐13) is mainly produced by T‐helper type 2 cells and induces B‐cell proliferation and antibody class switch. The role of IL‐13 in MG and MS is not known. We employed in situ hybridization with synthetic radiolabelled oligonucleotide probes to detect and enumerate blood and cerebrospinal fluid (CSF) mononuclear cells (MNC) expressing IL‐13 mRNA from patients with MG, MS, optic neuritis (ON), other inflammatory neurological diseases (OIND) and healthy controls. MG is associated with elevated levels of acetylcholine receptor (AChR) reactive IL‐13 mRNA expressing blood MNC compared to control patients. In MS, numbers of MBP‐reactive IL‐13 mRNA expressing MNC were higher compared to cultures without antigen stimulation. The levels of MBP‐reactive IL‐13 mRNA positive MNC were higher in MS compared to MG, but not other controls. There were no differences in spontaneous IL‐13 mRNA expressing blood MNC numbers between MG, MS, ON and control patients. The data suggest the involvement of IL‐13 in both MG and MS.