Allelic-dependent expression of an activating Fc receptor on B cells enhances humoral immune responses

Xinrui Li, Jianming Wu, Travis Ptacek, David T. Redden, Elizabeth E. Brown, Graciela S. Alarcón, Rosalind Ramsey-Goldman, Michelle A. Petri, John D. Reveille, Richard A. Kaslow, Robert P. Kimberly, Jeffrey C. Edberg

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


B cells are pivotal regulators of acquired immune responses, and recent work in both experimental murine models and humans has demonstrated that subtle changes in the regulation of B cell function can substantially alter immunological responses. The balance of negative and positive signals in maintaining an appropriate B cell activation threshold is critical in B lymphocyte immune tolerance and autoreactivity. FcγRIIb (CD32B), the only recognized Fcγ receptor on B cells, provides immunoglobulin G (IgG)-mediated negative modulation through a tyrosine-based inhibition motif, which down-regulates B cell receptor-initiated signaling. These properties make FcγRIIb a promising target for antibody-based therapy. We report the discovery of allele-dependent expression of the activating FcγRIIc on B cells. Identical to FcγRIIb in the extracellular domain, FcγRIIc has a tyrosine-based activation motif in its cytoplasmic domain. In both human B cells and B cells from mice transgenic for human FcγRIIc, FcγRIIc expression counter-balances the negative feedback of FcγRIIb and enhances humoral responses to immunization in mice and to BioThrax vaccination in a human anthrax vaccine trial. Moreover, the FCGR2C-ORF allele is associated with the risk of development of autoimmunity in humans. FcγRIIc expression on B cells challenges the prevailing paradigm of unidirectional negative feedback by IgG immune complexes via the inhibitory FcγRIIb, is a previously unrecognized determinant in human antibody/autoantibody responses, and opens the opportunity for more precise personalized use of B cell-targeted antibody-based therapy.

Original languageEnglish (US)
Article number216ra175
JournalScience Translational Medicine
Issue number216
StatePublished - Dec 18 2013


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