Pereira J, Soto M, Hidalgo P, Amaya S, Mezzano D
Departamento de Hematología-Oncología, Escuela de Medicina, P Universidad Católica de Chile, Santiago, Chile.
Rev Med Chil. 1997 Dec;125(12):1449-56.
Neonatal alloimmune thrombocytopenia (NAIT) is a result of fetomaternal incompatibility. Platelet destruction is caused by a maternal antibody directed against a fetal platelet antigen inherited from the father and lacking on the mother's platelets. The incidence and features of transplacental alloimmunization depend on the frequency of expression of platelet specific antigens; which are highly variable among different populations.
To determine the prevalence and characteristics of transplacental alloimmunization in a large group of pregnant women in Chile.
We studied 3,041 samples obtained during the third trimester of gestation. In all samples, anti platelet antibodies were screened by ELISA with platelet membranes fixed to a microtiter plate. Positive samples were further studied for antigenic specificity with the monoclonal antibody specific immobilization of platelet antigens (MAIPA) test.
Anti platelet antibodies were found in 261 samples (8.5%). The MAIPA test identified 6 samples with antibodies directed against major platelet membrane glycoproteins, 2 anti GPIb, 2 anti GPIIb/IIIa and 2 anti GPIa/IIa. In four cases, anti HLA antibodies coexisted. Two cases corresponded to well defined platelet antigen systems: one anti HPA-1a and one anti HPA-5b. No clinical evidence of thrombocytopenia of the newborn was detected in all these cases with anti GP antibodies.
A prevalence of platelet specific antibodies of 0.2% with only one anti HPA-1a was detected. These findings are in contrast with those of other populations but in accordance with the low frequency of the HPA-1 b/b phenotype in the Chilean population. The very low incidence of platelet specific antibodies and the lack of association with clinical thrombocytopenia in the newborn, do not support the recommendation of routine antenatal screening to all women in Chile.
新生儿同种免疫性血小板减少症（NAIT）是母胎不相容的结果。血小板破坏是由母体抗体针对从父亲遗传而来且母亲血小板缺乏的胎儿血小板抗原所致。经胎盘同种免疫的发生率和特征取决于血小板特异性抗原的表达频率；不同人群中该频率差异很大。
确定智利一大群孕妇中经胎盘同种免疫的患病率及特征。
我们研究了妊娠晚期获取的3041份样本。所有样本均通过酶联免疫吸附测定（ELISA）法，用固定于微量滴定板的血小板膜筛选抗血小板抗体。对阳性样本进一步采用血小板抗原单克隆抗体特异性固定试验（MAIPA）检测抗原特异性。
在261份样本（8.5%）中发现抗血小板抗体。MAIPA试验鉴定出6份样本含有针对主要血小板膜糖蛋白的抗体，2份抗糖蛋白Ib（GPIb），2份抗糖蛋白IIb/IIIa，2份抗糖蛋白Ia/IIa。4例中同时存在抗人白细胞抗原（HLA）抗体。2例对应明确的血小板抗原系统：1例抗血小板特异性抗原-1a（HPA-1a），1例抗血小板特异性抗原-5b（HPA-5b）。在所有这些抗糖蛋白抗体病例中均未检测到新生儿血小板减少症的临床证据。
检测到血小板特异性抗体患病率为0.2%，仅1例抗HPA-1a。这些发现与其他人群的结果不同，但与智利人群中HPA-1 b/b表型的低频率一致。血小板特异性抗体的极低发生率以及与新生儿临床血小板减少症缺乏关联，不支持对智利所有妇女进行常规产前筛查的建议。
