Research ArticleALLERGY

Platelets expressing IgG receptor FcγRIIA/CD32A determine the severity of experimental anaphylaxis

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Science Immunology  13 Apr 2018:
Vol. 3, Issue 22, eaan5997
DOI: 10.1126/sciimmunol.aan5997

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Potent platelets

Anaphylaxis results from inappropriate immune responses to allergens. Human platelets express the IgG receptor FcγRIIA/CD32A and release inflammatory mediators in response to their engagement, but their contribution to anaphylaxis is not well understood. Beutier et al. developed mouse models that express either human FcγRIIA/CD32A alone or the full human IgG receptor complexity to understand the role of platelets in anaphylaxis. Anaphylaxis induced a marked decrease in platelet levels, but preventive platelet depletion reduced anaphylaxis severity. A clinical study of patients with drug-induced anaphylaxis revealed that a severe reaction was likewise associated with fewer circulating platelets. Activated platelets released serotonin, which contributed to anaphylaxis severity. These results reveal a critical role for platelets in IgG-mediated anaphylaxis.