Alloimmunization against HPA-1a antigen is the most common cause of fetal/neonatal alloimmune thrombocytopenia (FNAIT) and often occurs during the first pregnancy. Thus, the question is should we introduce an antenatal screening for HPA-1a antigen/antibody? We screened 8013 pregnant women for HPA-1a by ELISA [1] and found 144 (1·8%) women to be HPA-1a-negative; the range reported for Caucasians being 1·6-2·5% [2]. All cases were confirmed by polymerase chain reaction sequence specific primers (PCR SSP) [3] to be HPA-1bb. Anti-HPA-1a was detected by monoclonal antibody immobilization of platelet antigens (MAIPA) [4] in 12 out of 122 HPA-1a-negative women (9·8%) available for further study. The incidence of HPA-1a immunization in 112 cases with a HPA-1a-positive neonate was 10·7%. Our results are comparable to those of Williamson et al . (11·9%) who also used the MAIPA for HPA-1a antibody detection [5]. Half of the HPA-1a immunized mothers were primigravida. Like others, we found that the negative predictive value of
Fetal RHD genotyping from maternal plasma may be used with confidence, although additional polymorphisms for confirmation of fetal DNA should be included for 100 percent predictive value (instead of 99.6%).
Background Transfusion-related acute lung injury (TRALI) is currently one of the most common causes of transfusion-related major morbidity and death. Among the many TRALI mediators, leucocyte antibodies have been identified as important triggers of severe TRALI.
In this study, platelet counts were determined from the cord blood of consecutive 9142 newborns. Neonates with known autoimmune thrombocytopenia were not included. The platelet count < 100 x 10(9)/L was found in 64 newborns. In five of them, neonatal alloimmune thrombocytopenia (NAIT) was diagnosed. The overall incidence of neonatal thrombocytopenia was 0.7%, the incidence of NAIT was about 10 times less. Serological and clinical observations are summarized from 238 thrombocytopenic newborns (54 from the above group and 184 previously referred to serological investigations). All of the newborns were divided into two groups: NAIT (46 cases) and other thrombocytopenias (192 cases). Among platelet-specific antibodies in NAIT, 91.4% were anti-HPA-1a, the rest were anti-HPA-1b and anti-HPA-5b. In the majority of the cases, antibodies were detectable by the platelet suspension immunofluorescence test (PSIFT) and monoclonal antibody immobilization of platelet antigens (MAIPA) assay. In 19.6% cases, antibodies were detectable by MAIPA only. In 10.9% of these cases, antibodies were undetectable. Thrombocytopenia < 50 x 10(9)/L and hemorrhagic diathesis were more often observed in NAIT than in other thrombocytopenias, whereas associated disorders that could contribute to thrombocytopenia, here observed almost only in the latter group. We also report certain other observations, such as the presence of anti-HLA antibodies, a rise in the anti-HPA-1 a antibody titer after infection without pregnancy, and a higher incidence of petechiae in nonimmune thrombocytopenia as compared with the incidence of low platelet counts.
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