Cytokine Regulation of B Cell Activation and Differentiation

The activation and differentiation of B cells are pivotal processes with major implications for host defense and the pathogenesis of immune-mediated diseases. During an immune response, B cells respond to cognate antigen by undergoing massive expansion and class switch recombination during the differentiation of B cells into plasma cells. This differentiation can take place either in follicles where they form germinal centers or in extrafollicular foci. With respect to these responses, B cells are exquisitely regulated by their microenvironment and various factors including cytokines. Cytokines represent a diverse group of soluble mediators that can have multifaceted function. It has been shown that many cytokines act on B cells as B cell growth and differentiation factors. This article focuses on the contribution of cytokines to B cell physiological function, including IL-2, IL-4, IL-10, IL-13, IL-21, IL-35, transforming growth factor γ, and interferons, and discusses their implications for the establishment of humoral immunity. We will also focus on the roles of IL-6 and how these contribute to human diseases.