Human T cell clones express functional homing receptors required for normal lymphocyte trafficking.

To function efficiently in vivo, lymphocytes must circulate from the blood into lymphoid tissues and other sites of immune reaction. Herein, we show that human cytotoxic and helper T cell clones and lines, maintained in vitro with IL-2, express the functional capacity to recognize and bind to high endothelial venules (HEV), a capacity essential for lymphocyte exit from the blood, and hence for normal lymphocyte trafficking. The expression of functional homing receptors distinguishes human T cell clones from their murine counterparts, which uniformly lack receptors for HEV and are unable to migrate normally from the blood in vivo. The results raise the possibility that human T cell clones may be more effective in mediating in vivo immune responses than is suggested by murine models.

In vitro analysis of the homing properties of human lymphocytes: developmental regulation of functional receptors for high endothelial venules.

Circulating lymphocytes leave the blood by binding to specialized high endothelial cells lining postcapillary venules in lymphoid organs or sites of chronic inflammations, migrating through the vessel wall into the surrounding tissue. The capacity of lymphocytes to recognize and bind to high endothelial venules (HEVs) is thus central to the overall process of lymphocyte traffic and recirculation. We show that viable human lymphocytes bind selectively to HEVs in frozen sections of normal human lymph nodes, thus defining a simple in vitro model for the study of human lymphocyte homing properties. Optimal conditions for the quantitative analysis of lymphocyte-HEV interaction are described. Furthermore, by using this assay, we demonstrate that the ability of human lymphocyte populations to bind to HEVs parallels their presumed migratory status in vivo. Thus, thymocytes and bone marrow cells, which are sessile in vivo, bind poorly to HEVs in comparison with mature circulating lymphocytes in peripheral blood or in peripheral lymphoid tissues. These results indicate that HEV-binding ability is a regulated property of mature lymphocytes and, as demonstrated previously in animal models, probably plays a fundamental role in controlling lymphocyte traffic in humans. The in vitro model of lymphocyte-HEV interaction thus provides a unique means to assay the migratory properties of normal and neoplastic human lymphocyte subsets, to analyze the role of lymphocyte traffic mechanisms in normal and pathologic inflammatory reactions, and to define some of the molecular mechanisms responsible for the control of lymphocyte migration and positioning in humans.

A lymphoid cell surface glycoprotein involved in endothelial cell recognition and lymphocyte homing in man.

We describe a 90-kDa lymphocyte surface glycoprotein, recognized by the monoclonal antibody Hermes-1, that is involved in endothelial cell recognition and lymphocyte trafficking in man. This molecule is selectively expressed on normal or transformed lymphoid cells that are able to recognize and bind to high endothelial venules (HEV, specialized vessels that mediate lymphocyte exit from the blood into lymphoid organs); appears to be linked to HEV recognition function since, in fluorescence-activated cell sorting of variants of a cloned cell line, HEV binding ability co-selects with the Hermes-1 antigen; bears the predominant cell surface epitopes recognized by heterologous anti-human lymphocyte antibodies able to interfere with lymphocyte binding to HEV; and is structurally similar to a previously described mouse lymphocyte surface receptor for HEV. These findings demonstrate that the molecule defined by Hermes-1 either functions as a specific lymphocyte surface receptor for HEV, or is both precisely coregulated and physically and/or functionally associated with such receptors. The expression of this putative receptor for HEV on normal human lymphocyte populations parallels, and thus presumably helps determine, their migratory status in vivo. Hermes-1 should be a powerful tool for analyzing the role of endothelial cell recognition in the traffic of normal and neoplastic human lymphocytes.