CD32A-expressing platelets determine the severity of experimental anaphylaxis.

Héloïse Beutier (1, 2) , Béatrice Hechler (3) , Ophélie Godon (1) , Yu Wang (1, 4) , Caitlin M. Gillis (1, 2) , Luc de Chaisemartin (5, 6) , Aurélie Gouel-Chéron (1, 7) , Stéphanie Magnenat (3) , Lynn E Macdonald (8) , Andrew J Murphy (8) , Sylvie Chollet-Martin (5, 6) , Dan Longrois (7, 9) , Christian Gachet (3) , Pierre Bruhns (1) , Friederike Jönsson (1)

1 Anticorps en thérapie et pathologie - Antibodies in Therapy and Pathology
2 SU FM - Sorbonne Université - Faculté de Médecine
3 BPP - Biologie et Pharmacologie des Plaquettes sanguines : hémostase, thrombose, transfusion
4 UPD7 - Université Paris Diderot - Paris 7
5 Laboratoire d'Immunologie "Autoimmunité et Hypersensibilités" [AP-HP Hôpital Bichat, Paris]
6 Cytokines, chimiokines et immunopathologie
7 Département d'Anesthésie Réanimation [CHU Bichat-Claude-Bernard]
8 Regeneron Pharmaceuticals [Tarrytown]
9 PHERE (UMR_S_1152 / U1152) - Physiopathologie et Epidémiologie des Maladies Respiratoires

Platelets are key regulators of vascular integrity; however, their role in anaphylaxis, a life-threatening systemic allergic reaction characterized by the loss of vascular integrity and vascular leakage, remains unknown. Anaphylaxis is a consequence of inappropriate cellular responses triggered by antibodies to generally harmless antigens, resulting in a massive mediator release and rapidly occurring organ dysfunction. Human platelets express receptors for immunoglobulin G (IgG) antibodies and can release potent mediators, yet their contribution to anaphylaxis has not been previously addressed in mouse models, probably because mice do not express IgG receptors on platelets. We investigated the contribution of platelets to IgG-dependent anaphylaxis in human IgG receptor-expressing mouse models and a cohort of patients suffering from drug-induced anaphylaxis. Platelet counts dropped immediately and markedly upon anaphylaxis induction only when they expressed the human IgG receptor FcγRIIA/CD32A. Platelet depletion attenuated anaphylaxis, whereas thrombocythemia substantially worsened its severity. FcγRIIA-expressing platelets were directly activated by IgG immune complexes in vivo and were sufficient to restore susceptibility to anaphylaxis in resistant mice. Serotonin released by activated platelets contributed to anaphylaxis severity. Data from a cohort of patients suffering from drug-induced anaphylaxis indicated that platelet activation was associated with anaphylaxis severity and was accompanied by a reduction in circulating platelet numbers. Our findings identify platelets as critical players in IgG-dependent anaphylaxis and provide a rationale for the design of platelet-targeting strategies to attenuate the severity of anaphylactic reactions.

Domains: Immunology; Allergology

Héloïse Beutier, Béatrice Hechler, Ophélie Godon, Yu Wang, Caitlin M. Gillis, et al.. CD32A-expressing platelets determine the severity of experimental anaphylaxis.. Science Immunology, 2018, 3 (22), ⟨10.1126/sciimmunol.aan5997⟩. ⟨pasteur-01928557⟩