Giuliani A L, Pora R, Verenini M, Unis L, Graldi G, Ferrari L, Lanza F, Wiener E, Lutz H U, Vesce F, Berti G
Dipartimento di Medicina Sperimentale e Diagnostica, Sezione di Patologia Generale, Università di Ferrara,
Acta Haematol. 1998 Dec;100(3):123-9. doi: 10.1159/000040886.
We have previously shown that a subpopulation of cord/fetal red blood cells (RBC) binds rabbit IgG antibodies raised against cord RBC and absorbed on adult RBC (F-IgG), while control IgG, raised against and absorbed on adult RBC (A-IgG), fails to do so. In the present study, F-IgG maintained its binding to cord RBC surface antigens following absorption on spectrin but not after absorption on skeleton-stripped RBC membranes. Spectrin-absorbed F-IgG- but not A-IgG-affinity-purified material from cord RBC contained polypeptides with apparent MW of complement receptor 1 (CR1) allotypes. Moreover, on immunoblotting these polypeptides reacted with 125I-F-IgG as well as with 125I-anti-CR1 mAb, and binding of 125I-anti-CR1 mAb was inhibited by unlabelled F-IgG. In addition, cord RBC incubated with F-IgG prior to reaction with anti-CR1 showed decreased fluorescence intensity on flow cytometry. Taken together the results suggest that F-IgG binds to CR1 which shows increased expression/accessibility on a subpopulation of cord/fetal RBC.
我们之前已经表明，脐带血/胎儿红细胞（RBC）的一个亚群能结合针对脐带血RBC产生并吸附于成人RBC上的兔IgG抗体（F-IgG），而针对成人RBC产生并吸附于其上的对照IgG（A-IgG）则不能。在本研究中，F-IgG在吸附于血影蛋白后仍能维持其与脐带血RBC表面抗原的结合，但在吸附于去除骨架的RBC膜后则不能。从脐带血RBC中通过F-IgG（而非A-IgG）亲和纯化得到的物质，经血影蛋白吸附后含有表观分子量为补体受体1（CR1）同种异型的多肽。此外，在免疫印迹中，这些多肽能与125I-F-IgG以及125I-抗CR1单克隆抗体发生反应，且未标记的F-IgG能抑制125I-抗CR1单克隆抗体的结合。另外，在与抗CR1反应之前先用F-IgG孵育的脐带血RBC，在流式细胞术中显示荧光强度降低。综合这些结果表明，F-IgG与CR1结合，而CR1在脐带血/胎儿RBC的一个亚群上表达增加/可及性增加。
