Janson M, McFarland J, Aster R H
Hum Immunol. 1986 Mar;15(3):251-62. doi: 10.1016/0198-8859(86)90001-7.
A monoclonal antibody with specificity for the Fc portion of IgG was used to determine the number of IgG alloantibody molecules bound at saturation to alloantigens of the PlA1 and HLA systems on normal human platelets. In preliminary studies, it was found that the number of cell-bound IgG molecules recognized by this probe correlates well with the number measured by electroimmunoassay, an independent measure of alloantibody binding. PlA1-positive platelets could be divided into two groups binding 34,000-43,000 or 19,000-24,000 alloantibody molecules. Family studies and studies with a cytolytic assay showed that the former group is homozygous and the latter heterozygous for PlA1. Because the number of glycoprotein IIIa (GPIIIa) molecules carrying the PlA1 determinant on the surface of normal platelets is thought to be about 40,000, these findings suggest that each GPIIIa molecule carries one PlA1 determinant. The number of class I HLA molecules expressed on normal platelets was considerably smaller than the number of PlA1 determinants, ranging from 4400 to 10,000 (HLA-A2), 870 to 8400 (Bw4), and 1300 to 5800 (Bw6). Preliminary analysis indicates that stronger or weaker expression of Bw4 and of Bw6 correlates with certain "private" HLA-B determinants carried on the HLA-B molecule as found in previous studies using an indirect method to measure alloantigen density. These findings appear to explain why antibodies reactive with platelet-specific antigens such as PlA1 react more strongly with platelets than HLA-specific antibodies in most serologic tests. The weak expression of HLA determinants on platelets of some subjects may account for the less than perfect correlation between in vitro compatibility tests and post-transfusion platelet survivals observed in most studies.
一种对IgG的Fc部分具有特异性的单克隆抗体被用于确定在正常人血小板上，饱和结合到PlA1和HLA系统同种抗原上的IgG同种抗体分子数量。在初步研究中，发现该探针识别的细胞结合IgG分子数量与通过电免疫测定法测得的数量密切相关，电免疫测定法是一种独立的同种抗体结合测量方法。PlA1阳性血小板可分为两组，一组结合34,000 - 43,000个同种抗体分子，另一组结合19,000 - 24,000个同种抗体分子。家系研究和细胞溶解试验研究表明，前一组为PlA1纯合子，后一组为PlA1杂合子。由于正常血小板表面携带PlA1决定簇的糖蛋白IIIa（GPIIIa）分子数量被认为约为40,000个，这些发现表明每个GPIIIa分子携带一个PlA1决定簇。正常血小板上表达的I类HLA分子数量明显少于PlA1决定簇数量，范围为4400至10,000（HLA - A2）、870至8400（Bw4）以及1300至5800（Bw6）。初步分析表明，Bw4和Bw6的较强或较弱表达与HLA - B分子上携带的某些“私有”HLA - B决定簇相关，这与先前使用间接方法测量同种抗原密度的研究结果一致。这些发现似乎解释了为什么在大多数血清学检测中，与血小板特异性抗原如PlA1反应的抗体与血小板的反应比HLA特异性抗体更强。一些受试者血小板上HLA决定簇的弱表达可能解释了在大多数研究中观察到的体外相容性试验与输血后血小板存活率之间不太完美的相关性。
