Official Journal of the British Blood Transfusion Society Transfusion Medicine | ORIGINAL ARTICLE Antibodies to human platelet antigens form a significant proportion of platelet antibodies detected in Indian patients with refractoriness to platelet transfusions A. S. Abraham, 1 M. P. Chacko, 1 N. A. Fouzia, 2 A. Srivastava 2 & D. Daniel 1 1 Department of Transfusion Medicine & Immunohematology, Christian Medical College, Vellore, India, and 2 Department of Clinical Hematology, Christian Medical College, Vellore, India Received 1 April 2017; accepted for publication 26 January 2018 SUMMARY Background: e transfusion of platelets is an important ther- apeutic strategy in bleeding patients with thrombocytopenia. However, some chronically transfused patients fail to achieve the appropriate platelet count increment following transfusion due to the presence of platelet alloantibodies. Objectives: e aims of this research were to study the preva- lence of platelet alloimmunisation and to characterise the platelet-reactive (PR) antibodies in haematology patients refractory to platelet transfusions in an Indian setting. Patients and methods: A total of 80 patients with a prior history of multiple transfusions (minimum of five cellular transfusions) were included in the study if they did not achieve an adequate corrected count increment within 24 h of the platelet transfu- sion. Patients with non-immunological causes of platelet refrac- toriness were excluded from the study. e test was performed on a blood sample of 4 mL of Ethylenediaminetetraacetic acid (EDTA) blood sample in which plasma was separated and stored at –80 ∘ C and underwent batch testing in PAK-2LE. Results: e overall prevalence of platelet alloimmunisation in our study was 60%. Of the 48 patients who were detected to have platelet antibodies, the combination of anti-human leuco- cyte antigen (HLA) and platelet-specific (PS) antibodies together constituted the majority of 54·2%. e overall prevalence of anti-HLA antibodies was 51·25% and of PS antibodies was 41·25% in the total study population of 80. Conclusion: e overall prevalence of PS antibodies in our study was greater than that reported by other groups in India and other countries. is needs to be considered, particu- larly in the management of patients refractory to platelet Correspondence: Dr Ancy Susan John, Department of Transfusion Medicine & Immunohematology, ASHA Building, 5th floor, Christian Medical College & Hospital, Vellore 632004, India. Tel.: +04162282533; fax: 04162232035; e-mail: drancyabraham@gmail.com, ancyjohn25@yahoo.com transfusions, where HLA-matched platelets constitute current best practice. Key words: alloimmunisation, corrected count increment, human leucocyte antigens, human platelet antigens, platelet refractoriness. Platelet transfusion is an essential component of supportive ther- apy in patients with haemato-oncological disorders as many of them present with varying degrees of thrombocytopenia leading to bleeding tendencies. However, repeated platelet transfusions may fail to show the desired increment in platelet counts. Causes of refractoriness may be multifactorial, with more than 80% being attributed to non-immunological causes like fever, sepsis, drugs and hypersplenism (Pavenski et al., 2012). e remain- ing immune causes are due to antibodies, commonly to human leucocyte antigens (HLA) and less frequently to human platelet antigens (HPA) (Pavenski et al., 2012). Such alloimmunisation can be attributed to prior exposure through previous transfu- sions, organ transplantation or pregnancy (Hod & Schwartz, 2008; Pavenski et al., 2012). HPA refers to amino acid substi- tutions on platelet glycoproteins (GPs), and antibodies against platelet GPs are platelet-specific (PS). HLA has a much wider tissue distribution. In our study, the PAK-2LE kit from Immu- cor Gti was used, which could only differentiate PS, i.e. platelet GP-directed antibodies (which might be platelet autoantibod- ies and/or HPA), from HLA antibodies. Antibodies against both platelet GPs and HLA have been classed as platelet-reactive (PR) antibodies in our study. e presence of PR antibodies can result in an inadequate response to platelet transfusions and life-threatening complications (Rebulla, 2005). Studies have doc- umented that anti-HLA antibodies are much more frequently implicated in platelet alloimmunisation than anti-HPA anti- bodies, and the current management strategy is the use of HLA-matched platelets for platelet refractoriness (Slichter et al., 1997; Kiefel et al., 2001; Rebulla, 2005). Pre-transfusion testing for anti- HLA and anti-HPA antibodies is not currently rou- tine practice, although literature regarding the prevalence of the © 2018 British Blood Transfusion Society doi: 10.1111/tme.12516