The IgM receptor FcμR limits tonic BCR signaling by regulating expression of the IgM BCR

Trang T T Nguyen, Kathrin Kläsener, Christa Zürn, Patricia A. Castillo, Ingrid Brust-Mascher, Denise M. Imai, Charles L. Bevins, Colin Reardon, Michael Reth, Nicole Baumgarth

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


The FcμR receptor for the crystallizable fragment (Fc) of immunoglobulin M (IgM) can function as a cell-surface receptor for secreted IgM on a variety of cell types. We found here that FcμR was also expressed in the trans-Golgi network of developing B cells, where it constrained transport of the IgM-isotype BCR (IgM-BCR) but not of the IgD-isotype BCR (IgD-BCR). In the absence of FcμR, the surface expression of IgM-BCR was increased, which resulted in enhanced tonic BCR signaling. B-cell-specific deficiency in FcμR enhanced the spontaneous differentiation of B-1 cells, which resulted in increased serum concentrations of natural IgM and dysregulated homeostasis of B-2 cells; this caused the spontaneous formation of germinal centers, increased titers of serum autoantibodies and excessive accumulation of B cells. Thus, FcμR serves as a critical regulator of B cell biology by constraining the transport and cell-surface expression of IgM-BCR.

Original languageEnglish (US)
Pages (from-to)321-333
Number of pages13
JournalNature Immunology
Issue number3
StatePublished - Feb 15 2017

ASJC Scopus subject areas

  • Immunology


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