Report on the Eleventh International Society of Blood Transfusion Platelet Genotyping and Serology Workshop

Abstract

The overall error rate for HPA-1-6 genotyping decreased from 2.7% in the tenth workshop to 0.8% in the eleventh workshop. The majority of laboratories were able to perform Gov genotyping, although the error rate was 7.5%. Detection of common clinically significant antibodies was good, although detection of the much rarer HPA-2b was problematic. There was considerable progress in the detection of anti-Gova. The lack of consensus over treatment of NAIT demonstrates uncertainty over optimal management of these patients.

A case report of neonatal alloimmune thrombocytopenic purpura: the importance of correct diagnosis for future pregnancies

“…3 The mother's HPA genotype was found to be: HPA-1b1b; HPA-2a2a; HPA-3a3b; HPA-4a4a; HPA-5a5a; HPA-6a6a. The father's HPA genotype was: HPA-1a1a; HPA-2a2a; HPA-3b3b: HPA-4a4a; HPA5a5b; HPA-6a6a.…”

“…For platelet antibody screening, the mother's serum was tested against a panel of genotyped platelets from known blood donors, using two different techniques: monoclonal antibody immobilization of platelet antigens (MAIPA) 3 and the platelet immunofluorescence test (PIFT) by flow cytometry. 3 The mother's HPA genotype was found to be: HPA-1b1b; HPA-2a2a; HPA-3a3b; HPA-4a4a; HPA-5a5a; HPA-6a6a.…”

“…3 The most important platelet antigen system involved in NAITP is HPA-1 (human platelet antigen 1), which accounts for 75-85% of cases, followed by HPA-5 (10-20% of cases).…”

Clinical Applications of Platelet Antibody and Antigen Testing

“…17 Early on, this workshop determined that a thorough workup for platelet alloantibodies required the use of multiple test methods, including a glycoprotein-specific assay, a test employing intact/whole platelets, and HPA genotyping. 18 Glycoprotein-specific assays are important since they are the most sensitive and specific for identifying the HPA specificity of serum antibodies. 19 An assay using intact platelets is critical to back up the glycoprotein-specific tests since the process of platelet lysis with detergent used in those assays followed by capture of GP with a specific monoclonal antibody can interfere with detection of antibodies that can only be detected using whole platelets.…”

Controversy: HLA Antibodies Responsible for Fetal/Neonatal Alloimmune Thrombocytopenia – an Update

“…International workshops revealed some aspects that need consideration in antibody determinations [10][11][12]. First, titration studies of HPA-1a antibodies show that even these antibodies are detectable at different titers among various laboratories.…”