DIAGNOSTIC MARKERS AND PREDICTORS OF NEONATAL IMMUNE THROMBOCYTOPENIA

Introduction. Neonatal thrombocytopenia presents a serious clinical problem, due to the possible development of dangerous bleeding in the fetus and the newborn.

Aim. To elucidate pathogenesis, methods of laboratory diagnostics as well as markers and predictors of neonatal immune thrombocytopenia (NAIT).

General findings. NAIT develops due to a mismatch between the mother and the fetus in terms of platelet alloantigens (HPA, Human Platelet Alloantigens). The mother produces alloantibodies against alloantigen, absent on her platelets, but expressed on the platelets of the fetus and the father. Antibodies enter the bloodstream of the fetus, thus causing destruction of the platelets of the fetus/newborn. Neonatal transimmune thrombocytopenia (NTIT) is diagnosed in some newborns (20–40%) from mothers with immune thrombocytopenic purpura (ITP). In this case, the platelets of the fetus/newborn are affected by ITP maternal autoantibodies. The following methods are used to diagnose neonatal immune thrombocytopenia: measurement of platelet-associated immunoglobulins G (TA-IgG); determination of antiplatelet circulating (serum) antibodies (cAB); identification of cAB antigens. In the case of NAIT, the mother has neither thrombocytopenia nor an increase in TA-IgG; however, cABs are detected that react with the father’s platelets carrying conflicting HPA alloantigen. In newborns, thrombocytopenia and increased TA-IgG are observed. Alloimmune conflict is confirmed by genotyping HPA of maternal and child alloantigens, and/or by determining the specificity of cABs using alloantigens of HPA-typed donors. In the Russian population, the most common causes of NAIT are conflicts with respect to HPA-1a, HPA-1b (33 % and 33%, respectively) and HPA-15a/b (25%) conflicts. In the case of NTIT, ITP mothers demonstrate reduced platelet count and increased TA-IgG, and thrombocytopenic newborns shows increased TA-IgG. The predictor of NTIT is the presence of antiplatelet cAB in pregnant women with ITP.

platelets, neonatal alloimmune thrombocytopenia, neonatal transimmune thrombocytopenia, immune thrombocytopenic purpura, antiplatelet antibodies, human platelet alloantigens

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