American Association of Immunologists, The Journal of Immunology, 1_Supplement(202), p. 123.12-123.12, 2019
DOI: 10.4049/jimmunol.202.supp.123.12
National Academy of Sciences, Proceedings of the National Academy of Sciences, 26(116), p. 12952-12957, 2019
Full text: Download
Abstract T cell-independent (TI) B cell response is critical for the early protection against pathogen invasion. The regulation and activation of Bruton’s tyrosine kinase (Btk) is known as a pivotal step of B cell antigen receptor (BCR) signaling in TI humoral immunity, as observed in patients with X-linked agammaglobulinemia (XLA) experiencing a high incidence of encapsulated bacterial infections. However, key questions remain as to whether well-established canonical BCR signaling pathway is sufficient to regulate the activity of Btk. Here, we find that inositol hexakisphosphosphate (InsP6) acts as a physiological regulator of Btk in BCR signaling. Absence of higher order inositol phosphates (InsPs), inositol polyphosphates, leads to an inability to mount immune response against TI antigens. Interestingly, the significance of InsP6-mediated Btk regulation is more prominent in IgM+ plasma cells. Hence, present study identifies higher order InsPs as principal components of B cell activation upon TI antigen stimulation and presents a novel mechanism for InsP-mediated regulation of the BCR signaling.