Gougos A, Letarte M
Division of Immunology, Hospital for Sick Children, Toronto, Ontario, Canada.
J Immunol. 1988 Sep 15;141(6):1925-33.
Staining of a variety of human tissue sections (lymph node, tonsil, spleen, thymus, kidney, lung, and liver) by the indirect immunoperoxidase method indicated that mAb 44G4, produced against a human pre-B leukemic cell line, was strongly reactive with vascular endothelium. All other cell types observed in these tissues were unreactive. Immunofluorescence staining of endothelial cells isolated from umbilical cord vein and grown in culture confirmed that mAb 44G4 recognized a surface membrane component of vascular endothelium. Granulocytes, monocytes, B and T lymphocytes, and T lymphocytes cultured in the presence of PHA for 72 h did not express the 44G4 Ag. mAb 44G4 reacted weakly with leukemic cells from 28 of 41 patients with non-T cell acute lymphocytic leukemia and 4 of 7 patients with acute myelocytic leukemia, whereas 8 of 10 cases of T cell acute lymphocytic leukemia were negative. Moderate reactivity with leukemic cell lines of pre-B and myelomonocytic origin was also observed. The level of 44G4 Ag on umbilical endothelial cells was three to five times that of leukemic cell lines and 25 times the average levels observed on leukemic cells isolated from patients. Immunoprecipitation of lysates prepared from surface-iodinated endothelial cells and the immunizing pre-B leukemic cell line revealed that the 44G4 Ag from both cell types was composed of two subunits of apparent m.w. 95,000 linked by disulfide bond(s). Comparison of the cellular localization and subunit structure of 44G4 to that of known Ag suggests that it represents a previously undescribed marker of endothelial cells.
采用间接免疫过氧化物酶法对多种人体组织切片（淋巴结、扁桃体、脾脏、胸腺、肾脏、肺和肝脏）进行染色，结果表明，针对人前B淋巴细胞白血病细胞系产生的单克隆抗体44G4与血管内皮细胞有强烈反应。在这些组织中观察到的所有其他细胞类型均无反应。对从脐静脉分离并在培养中生长的内皮细胞进行免疫荧光染色证实，单克隆抗体44G4识别血管内皮细胞的一种表面膜成分。粒细胞、单核细胞、B淋巴细胞和T淋巴细胞，以及在PHA存在下培养72小时的T淋巴细胞均不表达44G4抗原。单克隆抗体44G4与41例非T细胞急性淋巴细胞白血病患者中的28例以及7例急性髓细胞白血病患者中的4例的白血病细胞反应较弱，而10例T细胞急性淋巴细胞白血病患者中有8例为阴性。还观察到与前B细胞和骨髓单核细胞来源的白血病细胞系有中等反应性。脐静脉内皮细胞上44G4抗原的水平是白血病细胞系的三到五倍，是从患者分离的白血病细胞平均水平的25倍。对表面碘化的内皮细胞和免疫用前B淋巴细胞白血病细胞系制备的裂解物进行免疫沉淀，结果显示两种细胞类型的44G4抗原均由两个表观分子量为9 kDa的亚基通过二硫键连接而成。将44G4的细胞定位和亚基结构与已知抗原进行比较表明，它代表一种以前未描述的内皮细胞标志物。
