Advances in alloimmune thrombocytopenia laboratory investigations

Abstract

Alloimmune thrombocytopenia is mainly encountered during pregnancy when the mother becomes immunized against the fetal platelets antigens she lacks. The resulting fetal alloimmune thrombocytopenia, which incidence has been evaluated to 1/1000 live births in Caucasians, is usually severe and can lead to bleeding. Intracranial hemorrhage (20‐30% in retrospective studies) is the most severe complication leading to death (10‐15%) or neurological sequelae (20%). Due to the recurrence for incompatible fetuses in the subsequent pregnancies, antenatal management has been developed. The diagnosis of fetal or neonatal alloimmune thrombocytopenia is of utmost importance for the management of the affected infant and the subsequent pregnancies. The diagnosis is straightforward when a maternal alloantibody is detected directed against the offending antigen present in the infant. Although genotyping is widely used, unknown genetic variants may alter the results, and ethnic diversity is of importance. Genotype is not always phenotype. However phenotyping is somehow problematic because reference human sera have limited availability. The detection of the alloantibodies could be challenging. Currently the most widely techniques used are the antigen‐capture assays with mouse monoclonal antibodies. However false‐negative results may occur. New techniques are developed. In conclusion, international workshop exercises are of importance for further improvement and quality assurance proficiency.