CD40 signaling-mediated delay in terminal differentiation of B cells enables alternate fate choices during early divisions

• Published in: Molecular immunology 2022-04, Vol.144, p.1-15
• Main Authors: Vijayashankar, Devi Prasad, Vaidya, Tushar
• Format: Article
• Language: English
• Subjects: Animals; B cell; B-Lymphocytes; CD40 Antigens; CD40 signaling; Differentiation; Germinal Center; Lipopolysaccharides - pharmacology; LPS; Memory; Mice; Mice, Inbred C57BL; Plasma Cells; Proliferation potential
• ISSN: 0161-5890; 1872-9142
• DOI: 10.1016/j.molimm.2022.01.012

Memory B cells and differentiated plasma cells combine to confer sustained humoral immunity. Nonetheless, we are yet to understand how B cells decide between these fates. Although pan-T cell help augments plasma cell differentiation, signaling via CD40 alone is considered to be inhibitory. Here, we examine the capacity of CD40 signaling to interfere with lipopolysaccharide-induced differentiation. Whereas lipopolysaccharide stimulation yielded only short-lived plasmablasts, co-stimulation of CD40 enhanced activation, proliferation, survival, and isotype-switching, leading to alternate fate choices such as germinal center and memory B cells during early divisions. Contrary to the notion that CD40 signaling simply arrests differentiation, the survivors, at later time points, developed into long-lived mature plasma cells, after progressively losing their ability to get restimulated. Counterintuitively, as constitutive lipopolysaccharide stimulation itself hampered differentiation, we identified that the proliferation potential of cells acted alongside CD40 signaling. Accordingly, we propose a bi-layered regulation of differentiation – CD40 signaling and proliferation potential of cells independently inhibit the commitment to and maturation of differentiation, respectively. Elucidating such cell fate decision mechanisms will aid in better vaccine design and disease management. [Display omitted] •CD40 signaling enhances the activation, proliferation, and survival of B cells.•Isotype-switching, GC, and memory B cell fates are promoted during early divisions.•CD40-signaled B cells can be restimulated but this ability reduces over time.•CD40 signal does not halt but only delays differentiation into mature plasma cells.•Differentiation regulated by CD40 (commitment) and proliferation potential (maturation).