Efficacy of HPA‐1a (Pl^A1)‐negative platelets in a patient with post‐transfusion purpura

Abstract

Post-transfusion purpura (PTP) is a rare form of alloimmune thrombocytopenia that is selflimited but which carries a 10-15% mortality related to fatal hemorrhage. Immunomodulatory therapies such as plasmapheresis and intravenous immunoglobulin G (IVIg) can shorten the duration of thrombocytopenia. However, in a bleeding patient with PTP, more urgent therapy may be required. Textbooks of hematology [1][2][3] as well as reports in the literature [4,5] suggest that patients do not respond to platelet transfusions. We report a case of PTP in a patient homozygous for HPA-1b who suffered an intracranial hemorrhage. The patient was treated with IVIg and plasmapheresis. Because of her life-threatening bleeding, we also transfused the patient with HPA-1a-negative platelets. These transfusions consistently resulted in transient improvements in her platelet counts and may have limited the degree of intracranial bleeding. Our experience suggests that transfusion of platelets that lack the offending epitope in patients with PTP may be efficacious. Am.

Genotyping of Human Platelet Antigens 1 to 6 and 15 by High-Resolution Amplicon Melting and Conventional Hybridization Probes

“…Antibodies to HPA 1a are the most common cause, 9 and transfusions with platelets negative for HPA 1a are therapeutic in most cases. 10,11 HPAs 1, 3, 4, and 6 are found on integrin ␣ IIb ␤ 3 ; HPA 2 is found on the GPIb-IX-V complex; HPA 5 is found on integrin ␣ 2 ␤ 1 ; and HPA 15 is found on CD109. 5 Phenotyping of HPA 1 on platelets by flow cytometry has been reported.…”

Posttransfusion purpura with antibodies against human platelet antigen‐4a following checkpoint inhibitor therapy: a case report and review of the literature

“…PLT transfusion is generally not recommended because even PLTs that are negative for the implicated antigen are typically destroyed when transfused . However, HPA‐1a–negative blood products have reportedly been useful in some select cases . After an acute episode of PTP, there is still a risk for recurrence.…”

Consequences of transfusion of platelet antibody: a case report and literature review

“…21 Therefore, it is possible that alloantibodies against some epitopes are inherently more pathogenic and lead to more severe clinical presentation. 22 The syndrome of thrombocytopenia due to passive transfer of PLT antibody is self-limited, and patients with asymptomatic thrombocytopenia do not require treatment. For bleeding complications, IVIG, corticosteroids, and random-donor PLT transfusions have been successfully used.…”

“…As well, studies have shown that different alloantibodies against HPA‐1a recognize different epitopes on GPIIIa 21 . Therefore, it is possible that alloantibodies against some epitopes are inherently more pathogenic and lead to more severe clinical presentation 22 …”