298 Vox Sanguinis (2007) 93, 298–299 REPORT © 2007 The Author(s) Journal compilation © 2007 Blackwell Publishing Ltd. DOI: 10.1111/j.1423-0410.2007.00943.x This statement concerning the monoclonal-specific immobilization of platelet antigens (MAIPA) has been written on behalf of the International Society of Blood Transfusion – Working Party on Platelet Immunology. The MAIPA technique is considered as the gold standard reference technique in platelet immunology. The assay performed with reagents labelled for ‘research only’ is acceptable as long as it is regularly evaluated by participation of laboratories in national or international workshops held with reference laboratories. Key words: antibodies, capture assay, platelets. Since the identification of platelet antibodies, techniques have been developed for the more sensitive and specific detection of platelet-specific antibodies [1]. Specific assays as antigen capture assays have been avail- able since murine monoclonal antibodies (mAb) specific for the different platelet glycoproteins were produced [2,3]. Among these techniques, the mAb-specific immobilization of platelet antigens (MAIPA) was developed [4]. This assay is probably the most widely used, and has a good sensitivity and specificity. The advantage of the MAIPA is that antibody binding (both human and murine) to their respective antigen on the platelet membrane takes place in a phase when the conformational state of the antigen is relatively native. This prevents a reduction in sensitivity because of the loss of clinically important epitopes and reduces the incidence of false-positives because of the formation of clinically irrelevant neoepitopes. The MAIPA assay has been shown to be reproducible and a useful tool in the diagnosis of clinically significant immune- mediated platelet destruction such as maternofetal and neonatal alloimmune thrombocytopenia (NAIT), post- transfusion purpura (PTP), platelet-transfusion refractoriness, passive alloimmune thrombocytopenia and autoimmune disorders [5]. This assay is used not only for detection of antibodies against human platelet antigens (HPA), but also for platelet phenotyping, even if the antigen abundance is low, for example, HPA-5 and HPA-15. In addition to the rou- tine detection of HPA antibodies, the same technique has also been at the basis of the discovery of most the low-frequency HPAs [6]. Recently standardized quantitative MAIPA assays have been developed for quantification of platelet-specific alloantibodies [7,8]. To date, the MAIPA is considered to be the gold standard reference technique in platelet immunology and has been the Correspondence: Cecile Kaplan, Institut National de Transfusion Sanguine (INTS), Platelet Immunology Laboratory, 6 rue Alexandre Cabanel, 75015 Paris, France E-mail: ckaplan@ints.fr Blackwell Publishing Ltd Monoclonal platelet antigen capture assays (MAIPA) and reagents: a statement C. Kaplan 1 , J. Freedman 2 , Z. Foxcroft 3 , A. Husebekk 4 , P. Metcalfe 5 , E. Muniz-Diaz 6 , W. Ouwehand 7 , S. Panzer 8 , P. Rozman 9 , B. Skogen 10 on behalf of the International Society of Blood Transfusion – Working Party on Platelet Immunology 1 INTS, Platelet Immunology Laboratory, Paris, France 2 St Michael’s Hospital, Toronto, Ontario, Canada 3 South African National Blood Service, Johannesburg, South Africa 4 Institute of Medical Biology, University of Tromsø, Tromsø, Norway 5 National Institute for Biological Standards and Control, South Mimms, Potters Bar, UK 6 Immunohaematology Service, Banc de Sang i Teixits, Barcelona, Spain 7 University of Cambridge and National Blood Service, Cambridge, UK 8 Medical University, Vienna, Austria 9 Blood Transfusion Centre of Slovenia, Ljubljana, Slovenia 10 University Hospital North Norway, Tromsø, Norway Received: 10 May 2007, accepted 11 May 2007