Take H, Kashiwagi H, Tomiyama Y, Honda S, Honda Y, Mizutani H, Furubayashi T, Karasuno T, Nishiura T, Kanayama Y
Second Department of Internal Medicine, Osaka University Medical School, Japan.
Br J Haematol. 1993 Jul;84(3):387-91. doi: 10.1111/j.1365-2141.1993.tb03091.x.
The platelet antigen N(aka) was once considered to be a platelet-specific alloantigen and is carried on platelet membrane glycoprotein (GP) IV. Recent studies suggest that N(aka)-negative subjects lack platelet GPIV. GPIV is an important adhesive receptor and expressed on the surface of monocytes as well as of platelets. In the present study, flow cytometry was used to detect GPIV and N(aka) antigen on the surface of monocytes. N(aka) antigen was expressed on monocytes as well as on platelets in N(aka)-positive subjects (n = 6) (P-GPIV-positive subjects). To our surprise, monocytes of N(aka)-negative subjects (n = 7) (P-GPIV-negative subjects) having no anti-N(aka) antibody in their serum expressed GPIV and N(aka) antigen to almost the same degree as did the monocytes of P-GPIV-positive subjects. Competitive experiments using OKM5 (a monoclonal antibody against GPIV) and anti-N(aka) antibody showed that the epitope of anti-N(aka) antibody on monocytes was very close to that of OKM5. In two P-GPIV-negative subjects having anti-N(aka) antibody in their serum, GPIV and N(aka) antigen were not expressed on the surface of either monocytes or platelets. These results indicate that the GPIV molecules and N(aka) antigen are expressed on the surface of monocytes in the majority of P-GPIV-negative subjects, but that in a very few P-GPIV-negative subjects neither GPIV nor N(aka) antigen is expressed on the surface of their monocytes. We hypothesize that P-GPIV-negative subjects who carry neither GPIV nor N(aka) antigen on their monocytes produce anti-N(aka) antibody as a result of transfusion or pregnancy.
血小板抗原N（又名）曾被认为是一种血小板特异性同种抗原，由血小板膜糖蛋白（GP）IV携带。最近的研究表明，N（又名）阴性受试者缺乏血小板GPIV。GPIV是一种重要的黏附受体，在单核细胞以及血小板表面均有表达。在本研究中，采用流式细胞术检测单核细胞表面的GPIV和N（又名）抗原。在N（又名）阳性受试者（n = 6）（P-GPIV阳性受试者）中，N（又名）抗原在单核细胞以及血小板上均有表达。令我们惊讶的是，血清中无抗N（又名）抗体的N（又名）阴性受试者（n = 7）（P-GPIV阴性受试者）的单核细胞表达GPIV和N（又名）抗原的程度与P-GPIV阳性受试者的单核细胞几乎相同。使用OKM5（一种抗GPIV单克隆抗体）和抗N（又名）抗体进行的竞争性实验表明，单核细胞上抗N（又名）抗体的表位与OKM5的表位非常接近。在两名血清中有抗N（又名）抗体的P-GPIV阴性受试者中，GPIV和N（又名）抗原在单核细胞或血小板表面均未表达。这些结果表明，在大多数P-GPIV阴性受试者中，GPIV分子和N（又名）抗原在单核细胞表面表达，但在极少数P-GPIV阴性受试者中，其单核细胞表面既不表达GPIV也不表达N（又名）抗原。我们推测，单核细胞上既不携带GPIV也不携带N（又名）抗原的P-GPIV阴性受试者由于输血或妊娠而产生抗N（又名）抗体。
