TRAF6 is required for generation of the B-1a B cell compartment as well as T cell-dependent and -independent humoral immune responses.

• Main Authors: Takashi Kobayashi, Tae Soo Kim, Anand Jacob, Matthew C Walsh, Yuho Kadono, Ezequiel Fuentes-Pananá, Tomoko Yoshioka, Akihiko Yoshimura, Masahiro Yamamoto, Tsuneyasu Kaisho, Shizuo Akira, John G Monroe, Yongwon Choi
• Format: Article
• Language: English
• Published: Public Library of Science (PLoS) 2009-01-01
• Series: PLoS ONE
• Online Access: http://europepmc.org/articles/PMC2650412?pdf=render

TNF receptor superfamily members, such as CD40 and the Toll-like receptors (TLRs), regulate many aspects of B cell differentiation and activation. TRAF6 is an intracellular signaling adaptor molecule for these receptors, but its role in B cells has not been clarified by previous genetic approaches, as the systemic deletion of the TRAF6 gene results in perinatal lethality. Here we show that B cell-specific TRAF6 deficiency results in a reduced number of mature B cells in the bone marrow and spleen. Optimal T cell-dependent (TD) antigen responses, as characterized by isotype switching and long-lived plasma cell generation, are also impaired in B cell-specific TRAF6-deficient mice. B cell-specific TRAF6-deficient mice also exhibit lower levels of serum IgM and IgG2b and defective antigen-specific IgM production in response to T cell-independent (TI) antigens. Unexpectedly, TRAF6-deficient B cell progenitors are unable to generate CD5(+) B-1 cells. These results reveal critical roles for TRAF6 in TD and TI humoral immune responses and in inductive fate decisions necessary to generate the B-1 B cell compartment.