Mechanisms of immunoregulatory action of IL-10-producing B lymphocytes in dependence on the cytokine environment

Regulatory B lymphocytes (Bregs) represent a small heterogeneous subpopulation of B cells which participate in a regulation of immune responses by the antibody-independent mechanisms. The main mechanisms of Breg action is a production of anti-inflammatory cytokines or a direct cell contact through their surface molecules. This study deals with an induction of suppressive Bregs from mouse spleen B cells in vitro. We were aiming for a description of an influence of the selected cytokines to the induction of Bregs from lipopolysaccharide (LPS)-stimulated B cells and a determination of the mechanism of Breg action. We also analyzed the ability of inducted Bregs to produce interleukin-10 (IL) and to express genes for Fas ligand (FasL) and programmed death ligand 1 (PD-L1) molecules. We found that only two cytokines, IL-12 and IFN-γ, supported development of Bregs in a population of LPS-stimulated B cells. IFN-γ enhanced production of IL-10 and gene expression of FasL and PD-L1. Furthermore, we analyzed effects of Bregs on macrophages and their following action on T cells. Expression of costimulatory molecules CD80 and CD86, gene expression of IL-1α and the production of IL-6 were tested to determine the effects of macrophages on T cells. Macrophages influenced by Bregs had decreased ability to stimulate..