Carey G D, Chin Y H, Woodruff J J
J Immunol. 1981 Sep;127(3):976-9.
The first step in the entry of blood lymphocytes into lymph node is the binding of these cells to venules lined by high endothelium (HEV). This recognition event has been studied using a model system in which rat thoracic duct lymphocytes (TDL) adhere selectively to HEV when overlaid onto lymph node sections. We now report that this binding is increased by a lymph fraction designated adherence enhancing factor (AEF). Lymph depleted of cells and chylomicra was fractionated with (NH4)2SO4. Material that precipitated between 60 and 80% saturation was dissolved in buffer and extracted with chloroform/methanol; the aqueous phase was used as the source of AEF. The factor was nondialyzable, trypsin sensitive, and heat stable (70 degrees C, 30 min). Lymph node sections pretreated with AEF showed a 2- to 3-fold increase in the number of TDL bound to HEV and a 5 to 10-fold increase in the number of HEV with more than 5 adherent lymphocytes. The effect of AEF was specific: 1) No increase in lymphocyte binding to non-HEV areas of the tissue section occurred. 2) The binding of both TDL and spleen lymphoid cells to HEV was enhanced, but thymocyte attachment was not promoted. We conclude that AEF has biologic properties that might enable it to play a physiologic role in lymphocyte recirculation.
血液中的淋巴细胞进入淋巴结的第一步是这些细胞与高内皮小静脉（HEV）结合。这一识别过程已通过一个模型系统进行研究，在该系统中，当将大鼠胸导管淋巴细胞（TDL）覆盖在淋巴结切片上时，它们会选择性地黏附于HEV。我们现在报告，一种名为黏附增强因子（AEF）的淋巴成分可增强这种结合。去除细胞和乳糜微粒的淋巴液用硫酸铵分级分离。在60%至80%饱和度之间沉淀的物质溶解于缓冲液中，并用氯仿/甲醇萃取；水相用作AEF的来源。该因子不可透析，对胰蛋白酶敏感，且热稳定（70摄氏度，30分钟）。用AEF预处理的淋巴结切片显示，与HEV结合的TDL数量增加了2至3倍，且有超过5个黏附淋巴细胞的HEV数量增加了5至10倍。AEF的作用具有特异性：1）淋巴细胞与组织切片非HEV区域的结合未增加。2）TDL和脾淋巴细胞与HEV的结合均增强，但胸腺细胞的黏附未得到促进。我们得出结论，AEF具有生物学特性，可能使其在淋巴细胞再循环中发挥生理作用。
