Kiefel V, Santoso S, Mueller-Eckhardt C
Institut für Klinische Immunologie und Transfusionsmedizin, Justus-Liebig-Universität Giessen.
Beitr Infusionsther. 1990;26:386-8.
Platelet specific alloantibodies cause neonatal alloimmune thrombocytopenia (NAIT), posttransfusion purpura (PTP) and may be found in patients who are refractory to HLA-matched platelet transfusion. Most platelet alloantigen systems comprise two alleles: Zw(a)/Zw(b), Ko(a)/Ko(b), Bak(a)/Bak(b), Yuk(a)/Yuk/b). The corresponding antibodies are detected with the platelet immunofluorescence test, radioimmunoprecipitation, immunoblot, and with a glycoprotein-specific immunoassay. Epitopes of the Zw-, Bak-, and Yuk-alloantigen systems are localized on the GPIIb/IIIa complex. Recently, we characterized antibodies against two alleles of a new alloantigen system (Bra/Brb). Anti-Bra is the second most important antibody to cause NAIT, following Anti-Zwa. Anti-Brb was found in three polytransfused patients. The Br-antibodies may be detected using a glycoprotein-specific enzyme immunoassay (MAIPA assay) and radioimmunoprecipitation. The frequency of the Br-phenotypes in our population is Br(a+b-) 1%, Br(a+b+) 20%, Br(a-b+) 79%. The number of binding sites for Anti-Bra is 2000/platelet on homozygous and 1000/platelet on heterozygous platelets. The Br-alloantigens are localized on GPIa, which is identical with the alpha chain of VLA-2 on activated T-lymphocytes.
血小板特异性同种抗体可导致新生儿同种免疫性血小板减少症（NAIT）、输血后紫癜（PTP），并且在对人白细胞抗原（HLA）配型相合的血小板输注无效的患者中也可能被发现。大多数血小板同种抗原系统由两个等位基因组成：Zw(a)/Zw(b)、Ko(a)/Ko(b)、Bak(a)/Bak(b)、Yuk(a)/Yuk/b。相应的抗体可通过血小板免疫荧光试验、放射免疫沉淀、免疫印迹以及糖蛋白特异性免疫测定法检测。Zw-、Bak-和Yuk-同种抗原系统的表位定位于糖蛋白IIb/IIIa复合物上。最近，我们鉴定了针对一种新的同种抗原系统（Bra/Brb）两个等位基因的抗体。抗-Bra是继抗-Zwa之后导致NAIT的第二重要抗体。在三名多次输血的患者中发现了抗-Brb。可使用糖蛋白特异性酶免疫测定法（单克隆抗体固相血小板抗原分析试验）和放射免疫沉淀法检测Br抗体。我们人群中Br表型的频率为：Br(a+b-) 1%，Br(a+b+) 20%，Br(a-b+) 79%。抗-Bra在纯合血小板上的结合位点数量为每血小板2000个，在杂合血小板上为每血小板1000个。Br同种抗原定位于糖蛋白Ia上，糖蛋白Ia与活化T淋巴细胞上VLA-2的α链相同。
