B cells responses and cytokine production are regulated by their immune microenvironment

Abstract

The adaptive immune system consists of two types of lymphocytes: T and B cells. These two lymphocytes originate from a common precursor, yet are fundamentally different with B cells mediating humoral immunity while T cells mediate cell mediated immunity. In cytokine production, naïve T cells produce multiple cytokines upon activation while naïve activated B cells do not. B cells are capable of producing cytokines, but their cytokine production depends on their differentiation state and activation conditions. Hence, unlike T cells that can produce a large amount of cytokines upon activation, B cells require specific differentiation and activation conditions to produce cytokines. Many cytokines act on B cells as well. Here, we discuss several cytokines and their effects on B cells including: Interleukins, IL-7, IL-4, IL-6, IL-10, and Interferons, IFN-α, IFN-β, IFN-γ. These cytokines play important roles in the development, survival, differentiation and/or proliferation of B cells. Certain chemokines also play important roles in B cell function, namely antibody production. As an example, we discuss CCL28, a chemokine that directs the migration of plasma cells to mucosal sites. We conclude with a brief overview of B cells as cytokine producers and their likely functional consequences on the immune response.

Keywords: B cells; Chemokines; Cytokines; Interferon; Interleukins.

Figure 1. CCL28 expression is induced upon lactation

This results in the recruitment of IgA⁺ CCR10⁺ plasma cells from the respiratory and gastrointestinal tract. Hence, neonates receive passive immunity against respiratory and gut pathogens via breast milk.

Figure 2. B cells recruit Th2 cells to receive stimuli

Upon activation, naïve B cells express CCL17 and CCL22. These chemokines recruit CD4⁺CCR4⁺ Th2 T cells that provide B cells with appropriate cues to differentiate and produce cytokines.

Figure 3. Cytokine production by B cells

Arrows are cytokines produced by an immune cells that act on B cells. Inhibition lines are cytokines that B cells produce that have a regulatory effect on immune cells. Dashed arrows are cytokines produced by B cells that propagate/magnify effects on immune cells