Thromb Haemost 2015; 114(02): 313-324
DOI: 10.1160/TH14-11-0945
Cellular Haemostasis and Platelets
Schattauer GmbH

An atypical IgM class platelet cold agglutinin induces GPVI-dependent aggregation of human platelets

Isabel M. Sánchez Guiu
1   Centro Regional de Hemodonación, Hospital Universitario Morales Meseguer, Universidad de Murcia, IMIB-Arrixaca, Spain
,
Irene Martínez-Martinez
1   Centro Regional de Hemodonación, Hospital Universitario Morales Meseguer, Universidad de Murcia, IMIB-Arrixaca, Spain
,
Constantino Martínez
1   Centro Regional de Hemodonación, Hospital Universitario Morales Meseguer, Universidad de Murcia, IMIB-Arrixaca, Spain
,
José Navarro-Fernandez
1   Centro Regional de Hemodonación, Hospital Universitario Morales Meseguer, Universidad de Murcia, IMIB-Arrixaca, Spain
,
Faustino Garcia-Candel
2   Servicio de Hematología, Hospital Universitario Virgen de la Arrixaca, Spain
,
Francisca Ferrer-Marín
1   Centro Regional de Hemodonación, Hospital Universitario Morales Meseguer, Universidad de Murcia, IMIB-Arrixaca, Spain
,
Vicente Vicente
1   Centro Regional de Hemodonación, Hospital Universitario Morales Meseguer, Universidad de Murcia, IMIB-Arrixaca, Spain
,
Steve P. Watson
3   Birmingham Platelet Group, College of Medical and Dental Sciences, University of Birmingham, UK
,
Robert K. Andrews
4   Australian Centre for Blood Diseases, Monash University Melbourne, Melbourne, Victoria, Australia
,
Elizabeth E. Gardiner
4   Australian Centre for Blood Diseases, Monash University Melbourne, Melbourne, Victoria, Australia
,
María L. Lozano
1   Centro Regional de Hemodonación, Hospital Universitario Morales Meseguer, Universidad de Murcia, IMIB-Arrixaca, Spain
,
José Rivera
1   Centro Regional de Hemodonación, Hospital Universitario Morales Meseguer, Universidad de Murcia, IMIB-Arrixaca, Spain
› Author Affiliations

Financial support: We received funding from the Instituto de Salud Carlos III (ISCIII, PI10/02594, PI11/00566P, PI11/01256), RECAVA RD12/0042/0050 (ISCIII and FEDER), and Fundación Séneca (07703/GERM/07). ISG is supported by a fellowship from ISCIII (FI10/00535). IMM holds a Miguel Servet-I contract from ISCIII (CP13/00126). CM is an investigator from Fundación para la Formación e Investigación Sanitarias de la Región de Murcia (FFIS). SPW holds a British Heart Foundation Chair. RKA and EEG are supported by the National Health and Medical Research Council of Australia.
Further Information

Publication History

Received: 14 November 2014

Accepted after major revision: 15 March 2015

Publication Date:
21 November 2017 (online)

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Summary

Platelet cold agglutinins (PCA) cause pseudothrombocytopenia, spurious thrombocytopenia due to ex vivo platelet clumping, complicating clinical diagnosis, but mechanisms and consequences of PCA are not well defined. Here, we characterised an atypical immunoglobulin (Ig)M PCA in a 37-year-old woman with lifelong bleeding and chronic moderate thrombocytopenia, that induces activation and aggregation of autologous or allogeneic platelets via interaction with platelet glycoprotein (GP)VI. Patient temperature-dependent pseudothrombocytopenia was EDTA-independent, but was prevented by integrin αIIbβ3 blockade. Unstimulated patient platelets revealed elevated levels of bound IgM, increased expression of activation markers (P-selectin and CD63), low GPVI levels and abnormally high thromboxane (TX)A2 production. Patient serum induced temperature- and αIIbβ3-dependent decrease of platelet count in allogeneic donorcitrated platelet-rich plasma (PRP), but not in PRP from Glanzmann’s thrombasthenia or afibrinogenaemia patients. In allogeneic platelets, patient plasma induced shape change, P-selectin and CD63 expression, 14C-serotonin release, and TXA2 production. Activation was not inhibited by aspirin, cangrelor or blocking anti-Fc receptor (FcγRIIA) antibody, but was abrogated by inhibitors of Src and Syk, and by a soluble GPVI-Fc fusion protein. GPVI-deficient platelets were not activated by patient plasma. These data provide the first evidence for an IgM PCA causing platelet activation/aggregation via GPVI. The PCA activity persisted over a five-year follow-up period, supporting a causative role in patient chronic thrombocytopenia and bleeding.