Neonatal alloimmune thrombocytopenia caused by anti-HPA antibodies in pregnant Chinese women: a study protocol for a multicentre, prospective cohort trial

Abstract

BackgroundNeonatal alloimmune thrombocytopenia (NAIT), caused by maternal antibodies raised against alloantigens carried on foetal platelets, is a very common haematological abnormality in newborns worldwide. However, baseline data on NAIT in China are lacking. Therefore, this study seeks to explore the incidence of alloantibody against the human platelet antigen (HPA) in pregnant women and its associations with NAIT in China.MethodsA multicentre, prospective cohort study design will be used, and 55,497 pregnant women will be recruited for the first screening of the anti-HPA antibody at 12 to 28 weeks of gestational age. Subjects who are positive in the first screening for the anti-HPA antibody will be included in the exposure group. Re-tests of the antibody titre, antigen-specificity and genotyping of HPA and HLA will be conducted during admission. A ratio of 1:1 paired individuals with the same ethnicity and parity but testing negative for the anti-HPA antibody will be randomly selected to be included in the non-exposure group. NAIT will be diagnosed in the newborns on day one of the birth. The HPA of the neonates in the exposure group will also be genotyped by sequencing. Associations of maternal HLA with the occurrence of the anti-HPA antibody and correlation of the severity of NAIT with the titre of the anti-HPA antibody will be further analysed.DiscussionThe study is expected to provide baseline data on NAIT in China. Besides, we hope to find out a population who expresses particular HLA molecules has significant higher risk of HPA alloimmunization in Chinese individuals. We also hope to find a Chinese-specific cut-off antibody titre for the prediction of the severity of NAIT and to provide a means to evaluate the necessity of antenatal treatment.Trial registrationClinicalTrials.gov: NCT02934906 (date registered: 13.10.2016).

Timely diagnosis and treatment of neonatal alloimmune thrombocytopenia caused by anti HPA-3a antibody

“…On the cases of thrombocytopenia which are mainly caused by HPA-3a antibodies, intravenous immunoglobulin treatment may be the best choice for neonates with immune thrombocytopenia. [24] The mechanism of action of IVIG has been assumed as competitive inhibition of antibody binding or reticuloendothelial blockage. [25] As for our patient, the treatment with IVIG appeared to be effective after 4 days infusion due to the timely diagnosis on the newborn, which proved the significance of early diagnosis and treatment on NAIT.…”

Human Platelet Antigens in Brazilian Multiethnic Populations: Occurrence of Regional Variation and Frequency in a Large Urban Center (Belo Horizonte)

“…The frequency of these antigens varies according to ethnicity, which causes differences in the incidence of antigen specificity of anti-HPA antibodies and in the morbidity of AIT in different populations [5,6]. In Europeans, alloantibodies are formed most commonly against HPA-1, -2, and -5.…”