Journal
FRONTIERS IN IMMUNOLOGY
Volume 9, Issue -, Pages -Publisher
FRONTIERS MEDIA SA
DOI: 10.3389/fimmu.2018.01244
Keywords
IgE; IgG; Fc gamma RIIb; Fc receptors; mast cells; anaphylaxis; immediate hypersensitivity; food allergy
Categories
Funding
- NIH [1R01AI119918, 5T32AI007512-28, 1K01DK106303-01, R01 AR056720 NIH/NIAMS, P30 AR069625 NIH/NIAMS]
- Bunning Family Foundation
- Nanji Family Fund
- Rao Chakravorti Family fund
- Christine Olsen and Robert Small Food Allergy Research Fund
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Immediate hypersensitivity reactions are induced by the interaction of allergens with specific IgE antibodies bound via FceRI to mast cells and basophils. While these specific IgE antibodies are needed to trigger such reactions, not all individuals harboring IgE exhibit symptoms of allergy. The lack of responsiveness seen in some subjects correlates with the presence of IgG antibodies of the same specificity. In cell culture studies and in vivo animal models of food allergy and anaphylaxis such IgG antibodies have been shown to exert suppression via Fc gamma RIIb. However, the reported absence of this inhibitory receptor on primary mast cells derived from human skin has raised questions about the role of IgG-mediated inhibition of immediate hypersensitivity in human subjects. Here, we tested the hypothesis that mast cell Fc.RIIb expression might be tissue specific. Utilizing a combination of flow cytometry, quantitative PCR, and immunofluorescence staining of mast cells derived from the tissues of humanized mice, human skin, or in fixed paraffin-embedded sections of human tissues, we confirm that Fc.RIIb is absent from dermal mast cells but is expressed by mast cells throughout the gastrointestinal tract. IgE-induced systemic anaphylaxis in humanized mice is strongly inhibited by antigen-specific IgG. These findings support the concept that IgG, signaling via Fc.RIIb, plays a physiological role in suppressing hypersensitivity reactions.
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