Adhesion-promoting receptors on phagocytes.
Phagocytes express a family of structurally related receptors, LFA-1, CR3, and p150,95, that mediate adhesion of leukocytes to a variety of cells and surfaces. LFA-1 mediates the binding of killer T cells to targets, CR3 mediates binding of phagocytes to iC3b-coated surfaces and to endothelial cells, and LFA-1, CR3, and p150,95 each mediate the binding of bacterial lipopolysaccharide. Here we review the structure and function of each of these receptors and present evidence that they are related to a larger class of adhesion-promoting receptors called integrins. Of particular emphasis are observations that the capacity of these receptors to promote adhesion is strongly and reversibly modulated by both soluble and surface-bound stimuli. We review this form of regulation and present evidence that changes in the binding activity of adhesion-promoting receptors is accomplished by changes in the two-dimensional distribution of receptors in the plane of the membrane. Inactive receptors are randomly distributed in the membrane, and their ability to bind a ligand-coated surface is enabled by a ligand-independent movement into small clusters. The implications of these structural features are discussed.
Wright
S D
SD
Laboratory of Cellular Physiology and Immunology, Rockefeller University, New York, NY 10021.
Detmers
P A
PA
D000943:Antigens, Differentiation / Q000276:immunology; D002448:Cell Adhesion; D006801:Humans; D016169:Lymphocyte Function-Associated Antigen-1; D010585:Phagocyte Bactericidal Dysfunction / Q000276:immunology; D010586:Phagocytes / Q000276:immunology / Q000502:physiology*; D011951:Receptors, Complement / Q000276:immunology; D017463:Receptors, Complement 3b; D011971:Receptors, Immunologic / Q000502:physiology*; D016028:Receptors, Leukocyte-Adhesion / Q000276:immunology
D000943:Antigens, Differentiation; D016169:Lymphocyte Function-Associated Antigen-1; D011951:Receptors, Complement; D017463:Receptors, Complement 3b; D011971:Receptors, Immunologic; D016028:Receptors, Leukocyte-Adhesion