The role of reactive oxygen intermediates (ROI) in B cell activation, proliferation, and differentiation (132.10)

Abstract

Abstract Reactive oxygen intermediates (ROI) are generated during mitochondrial respiration, receptor ligation, and microorganism digestion. Ligation of the BCR resulted in ROI production that reaches a maximum by 15 minutes. ROI can modify all macromolecules, but we are interested in reversible oxidation events that modulate signaling. Our focus is on cysteine sulfenic acid, the first cysteine oxidation product. Using 5,5 dimethyl-1,3-cyclohexanedione (dimedone), a compound that covalently reacts with sulfenic acid to prevent further oxidation or reduction, we addressed the role of reversible sulfenic acid formation in mature B cell activation, proliferation and differentiation. Following incubation with antibodies against surface bound Immunoglobulin M (IgM), mature B cells divide several times by three days. Incubation with dimedone results in a concentration dependent block of the initial division. This contrasted with dimedone-pretreated CpG DNA and LPS-stimulated B cells, where subsequent divisions were reduced compared to vehicle-treated cells. Dual stimulation with BAFF, CD40, and IL-4 did not rescue the effect of dimedone on proliferation. Cells pretreated with dimedone did not flux calcium when incubated with IgM, and in vitro plasma cell differentiation was also decreased. These studies demonstrate that mature B cell activation, proliferation and differentiation require reversible cysteine sulfenic acid formation.