Four molecular pathways of T cell adhesion to endothelial cells: roles of LFA-1, VCAM-1, and ELAM-1 and changes in pathway hierarchy under different activation conditions.
T cell adhesion to endothelium is critical to lymphocyte recirculation and influx into sites of inflammation. We have systematically analyzed the role of four receptor/ligand interactions that mediate adhesion of peripheral human CD4+ T cells to cultured human umbilical vein endothelial cells (HUVEC): T cell LFA-1 binding to ICAM-1 and an alternative ligand ("ICAM-X"), T cell VLA-4 binding to VCAM-1, and T cell binding to ELAM-1. Contributions of these four pathways depend on the activation state of both the T cell and HUVEC, and the differentiation state of the T cell. ELAM-1 plays a significant role in mediating adhesion of resting CD4+ T cells to activated HUVEC. LFA-1 adhesion dominates with PMA-activated T cells but the strength and predominant LFA-1 ligand is determined by the activation state of the HUVEC; while ICAM-1 is the dominant ligand on IL-1-induced HUVEC, "ICAM-X" dominates binding to uninduced HUVEC. Adhesion via VLA-4 depends on induction of its ligand VCAM-1 on activated HUVEC; PMA activation of T cells augments VLA-4-mediated adhesion, both in the model of T/HUVEC binding and in a simplified model of T cell adhesion to VCAM-1-transfected L cells. Unlike LFA-1 and VLA-4, ELAM-1-mediated adhesion is not increased by T cell activation. Differential expression of adhesion molecules on CD4+ T cell subsets understood to be naive and memory cells also regulates T/HUVEC adhesion. Naive T cell adhesion to HUVEC is mediated predominantly by LFA-1 with little or no involvement of the VLA-4 and ELAM-1 pathways. In contrast, memory T cells bind better to HUVEC and utilize all four pathways. These studies demonstrate that there are at least four molecular pathways mediating T/HUVEC adhesion and that the dominance/hierarchy of these pathways varies dramatically with the activation state of the interacting cells and the differentiation state of the T cell.
Shimizu
Y
Y
Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.
Newman
W
W
Gopal
T V
TV
Horgan
K J
KJ
Graber
N
N
Beall
L D
LD
van Seventer
G A
GA
Shaw
S
S
D000818:Animals; D015703:Antigens, CD / Q000502:physiology; D015704:CD4 Antigens / Q000032:analysis; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000502:physiology*; D002478:Cells, Cultured; D019040:E-Selectin; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1; D007739:L Cells / Q000502:physiology; D008024:Ligands; D016169:Lymphocyte Function-Associated Antigen-1 / Q000502:physiology*; D051379:Mice; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000502:physiology; D013601:T-Lymphocytes / Q000187:drug effects / Q000502:physiology*; D014162:Transfection; D019010:Vascular Cell Adhesion Molecule-1
D015703:Antigens, CD; D015704:CD4 Antigens; D015815:Cell Adhesion Molecules; D019040:E-Selectin; D008024:Ligands; D016169:Lymphocyte Function-Associated Antigen-1; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1