Posttransfusion purpura (PTP) is an uncommon, but potentially fatal, transfusion reaction characterized by profound thrombocytopenia and bleeding. PTP is caused by alloimmunization to human platelet specific antigens following blood component transfusion. Although there is evidence of a wide serological spectrum of culprit antibodies implicated, Anti-human-platelet-antigen- (HPA-) 1a is the mos...

Platelets share antigens with other cells such as ABH and HLA class I antigens, but also express specific antigens. Platelet specific antigens are identified according to a nomenclature devised by the International Society of Blood Transfusion and are referred to as Human Platelet Antigens (HPA). These include glycoproteins expressed on platelet surfaces such as GPIIb/IIIa, the von Willebrand f...

OBJECTIVE The objective of this study was to evaluate the frequencies of human platelet antigens in oncohematological patients with thrombocytopenia and to analyze the probability of their incompatibility with platelet transfusions. METHODS Platelet antigen genotyping was performed by sequence-specific primer polymerase chain reaction (SSP-PCR) for the HPA-1a, HPA-1b, HPA-2a, HPA-2b, HPA-3a, ...

Fetomaternal alloimmune thrombocytopenia (FMAIT) is caused by maternal generation of antibodies specific for paternal platelet antigens and can lead to fetal intracranial hemorrhage. A SNP in the gene encoding integrin beta3 causes a clinically important maternal-paternal antigenic difference; Leu33 generates the human platelet antigen 1a (HPA-1a), whereas Pro33 generates HPA-1b. As a potential...

Alloimmunization to human platelet antigens (HPAs) may occur either during pregnancy, when a HPA‑negative mother gives birth to a newborn who inherits HPAs from the father, or following blood transfusion or stem cell transplantation. Antiplatelet alloantibodies do not cause thrombocytopenia in a patient, but their detection must always be recorded in medical records because they may induce feta...

The human platelet-specific alloantigens HPA-2a and HPA-2b (= Kob and Koa) together constitute a biallelic antigen system. The HPA-2 antigens have not, to date, been located on a particular platelet membrane molecule. Here, we describe the localization of these antigens on platelet glycoprotein (GP) Ib alpha. Platelets from two patients with the Bernard-Soulier syndrome (BSS) were HPA-2(a-,b-) ...

Polymorphism of human platelet antigens (HPAs) leads to alloimmunizations and immune-mediated platelet disorders including fetal-neonatal alloimmune thrombocytopenia (FNAIT), posttransfusion purpura (PTP), and platelet transfusion refractoriness (PTR). HPA typing and knowledge of antigen frequency in a population are important in particular for the provision of HPA-matched blood components for ...

Platelets from 200 random Dutch blood donors were typed for the human platelet alloantigens HPA-1 to -5 recognized at present and for Naka. Naka is an epitope on glycoprotein IV, not expressed on the platelet of individuals with hereditary GP IV deficiency. Platelet immunofluorescence and monoclonal antibody-specific immobilization of platelet antigens (MAIPA) were applied for this purpose. The...

Background: Thrombocytopenia occurs in 1-5 % of newborns (platelet count < 150 × 109/L). Low platelet 50 109/L leads to the hemorrhagic syndrome, with one its causes being neonatal alloimmune thrombocytopenia resulting from incompatibility between mother and fetus human antigens (HPA) inherited father absent mother, which formation maternal antibodies. Anti-HPA-1a, anti-HPA-5b, anti-HPA-3a, ...

Platelets are metabolically very active cells which support primary hemostasis and blood coagulation. Their glycocalyx layer on the external membrane contains a series of complex glycoprotein molecules, which are classified from glycoprotein-I to glycoprotein-X. The platelet membrane glycoproteins act as receptors for many adhesive proteins such as collagen, von-Willebrand factor, fibronectin, ...