Background: Knowing the human platelet angens (HPA) and genes frequency in different populaons is important not only for populaon studies but also for clinical transfusion pracce. HPA genes frequency in Iran is not evaluated, so we invesgated the HPA-2, HPA-3, and HPA-5 frequency and their polymorphism. Materials and Methods: DNA from 120 Iranians (99 Iranian blood donors and 21 paents wi...

This report describes the production and characterisation of a freeze-dried preparation of pooled human plasma, containing IgG antibodies against the human platelet antigen l a (HPA-la). Plasma samples containing potent anti-HPA-la were pooled and freeze dried in 1 mL ampoules. In addition, three individual plasma samples were selected which had varying levels of antiHPA-la activity. The anti-H...

A single nucleotide polymorphism (SNP) at position 196 in the beta 3 integrin causes a Leu33Pro substitution in the mature protein. Alloimmunization against the beta 3Leu33 form (human platelet antigen [HPA]-1a, Pl(A1), Zw(a)) in patients who are beta 3Pro33 homozygous (HPA-1b1b, Pl(A2A2), Zw(bb)) causes neonatal alloimmune thrombocytopenia, posttransfusion purpura, or refractoriness to platele...

Glycoprotein (GP) Ibalpha is the functionally dominant subunit of the platelet GPIb-IX-V receptor complex, with the von Willebrand factor (vWF) binding site residing on the amino-terminus. A threonine for methionine-145 replacement of GPIbalpha is associated with the human platelet antigen (HPA)-2 system. To study the structural and functional consequences of this mutation, both forms of GPIbal...

Immune thrombocytopenia occurs when antibodies targeting specific glycoproteins (GPs) on the platelet surface lead to their destruction. Tests of the patient’s platelets and serum for antibodies and typing of DNA for human platelet alloantigens (HPA) can be helpful in confirming a clinical diagnosis of immune thrombocytopenia. A thorough workup includes 1) serum tests using intact platelets; 2)...

We applied a polymerase chain reaction-sequence specific primer (PCR-SSP) method developed by other researchers to study 4 families of newborns with neonatal alloimmune thrombocytopenia (NAITP) in which serology had provided inconclusive human platelet antigen (HPA) typing data. This method allowed for the identification of the newborn HPAs which were incompatible with their respective mothers....

In the Trial to Reduce Alloimmunization to Platelets (TRAP) study, 101 of 530 participants became refractory to platelet transfusions without evidence of HLA or human platelet antigen (HPA) antibodies. We used a more sensitive bead-based assay to detect and quantify HLA antibodies and a qualitative solid-phase enzyme-linked immunosorbet assay for HPA to determine whether low-level antibodies co...

Some mothers produce antibodies to the platelet antigens of their fetuses. Exposure to these antigens may occur owing to prior transfusions or through feto-maternal hemorrhage during gestation or delivery. The sensitizing antigen is usually an epitope of one of the glycoproteins (GP) found on the platelet membrane. Specific GPs act as receptors for factors important in hemostasis, such as von W...

Maternal alloantibodies against the human platelet Ag (HPA)-1a allotype of the platelet beta(3) integrin GpIIb/IIIa can cause severe fetal or neonatal hemorrhage. Almost all anti-HPA-1a-immune mothers are homozygous for HPA-1b and carry HLA-DR52a (DRB3*0101). The single Pro(33) -->Leu substitution (HPA-1b-->HPA-1a) was previously predicted to create a binding motif for HLA-DR52a that can lead t...