The expression of lymphocyte adhesion molecules on cultured high endothelial cells.

Abstract

Lymphocytes enter lymph nodes (LN) from the blood by penetrating the walls of high endothelial venules (HEV). The initial step in this process involves the selective adhesion of lymphocytes to the luminal surface of high endothelial cells. Detailed studies of this adhesion process using the frozen section assay developed by Stamper and Woodruff (1) have identified receptors on the surfaces of rat (2) and mouse (3) lymphocytes which mediate adhesion to HEV in LN cryostat sections. These receptors also mediate lymphocyte migration into LN of intact recipients. A natural conclusion from these studies is that HEV express surface adhesion molecules (ligands or complementary receptors) for lymphocytes and the expression of adhesion molecules by HEV regulates lymphocyte migration from the blood. At least two sets of lymphocyte receptor-HEV adhesion molecules exist in rodents. One directs lymphocyte migration into peripheral LN and the second directs lymphocyte migration into Peyer’s patches (3–5). The expression of lymphocyte adhesion molecules by HEV is poorly understood. The role of endothelium in this intriguing process could be studied using isolated high endothelial cells (HEC). The recent successes achieved with the isolation and long-term culture of aortic, venous and capillary endothelium prompted an attempt at the isolation of HEC from rat lymph nodes.