Invariant natural killer T-cell anergy to endogenous myelin acetyl-glycolipids in multiple sclerosis

Abstract

Objective: To extend our studies on the glycolipid-reactive invariant Natural Killer T-cell (iNKT-cell) function in multiple sclerosis (MS), we investigated the stimulatory activities of two myelin-derived glycolipids which are poly-acetylated derivatives of β-galactosylceramide, designated PA-GC and FMC-7 (fast migrating cerebroside-7). Methods: Peripheral blood mononuclear cells from MS patients or healthy control subjects were stimulated with PA-GC, FMC-7 or α-galactosylceramide (α-GalCer). In cell expansion studies, the frequencies of iNKT-cells were analysed before and after glycolipid stimulation by flow cytometry. Analysis of cytokines in culture supernatants was performed using Th1/Th2 multiplexing and flow cytometry. Results: In healthy subjects, the myelin-derived glycolipids significantly expanded iNKT-cells in a similar way to α-GalCer and induced significant increases of Th1, Th2 and Th17 cytokines in peripheral blood cultures. In marked contrast, MS patients failed to respond to either of the myelin-derived acetylated glycolipids or to α-GalCer stimulation indicating an anergic response. Conclusions: We propose that myelin-derived glycolipids stimulate iNKT-cell responses in vivo and that regulation or inhibition of this response may determine the immune response or disease onset in the CNS.