title: Interaction of histidine-rich glycoprotein with human T lymphocytes.
abstract: Histidine-rich glycoprotein (HRGP), a human plasma and platelet protein, interacts with multiple ligands in vitro, including heparin, plasminogen, thrombospondin, and fibrinogen/fibrin. In this study, the binding of HRGP to human T lymphocytes was characterized. The binding was specific, concentration-dependent, saturable, and reversible. Scatchard plot analysis revealed two classes of binding sites: the high affinity class had an apparent dissociation constant (Kd) of 1.92 X 10(-8) M, with 0.92 X 10(4) sites/cell, and the low affinity class had a Kd of 4.97 X 10(-7) M, with 3.7 X 10(4) sites/cell. HRGP binding to T cells in the presence of HRGP-depleted serum was comparable to that observed in buffer. Dot-blot analysis showed that HRGP bound to specific T cell proteins. Using both HRGP affinity chromatography and immunoprecipitation with affinity-purified anti-HRGP IgG, a major 56-kDa HRGP-binding protein in surface labeled T cell lysates was demonstrated. The 56-kDa protein was shown not to be related to the CD2 molecule on T cells. The binding characteristics of HRGP to T lymphocytes indicate a specific ligand-receptor interaction. This is the first demonstration of HRGP binding to a cell surface, and its binding to human T cells may play an important role in T lymphocyte biology.
authors.affiliation: Department of Medicine, Stanford University Medical School, California 94305.
authors.forename: K
authors.initials: K
authors.lastname: Saigo
authors.forename: M
authors.initials: M
authors.lastname: Shatsky
authors.forename: L J
authors.initials: LJ
authors.lastname: Levitt
authors.forename: L K
authors.initials: LK
authors.lastname: Leung
mesh_terms: D000945:Antigens, Differentiation, T-Lymphocyte; D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D001665:Binding Sites; D001667:Binding, Competitive; D001798:Blood Proteins; D018801:CD2 Antigens; D002461:Cell Line, Transformed; D002712:Chlorides / Q000494:pharmacology; D002846:Chromatography, Affinity; D006023:Glycoproteins; D006493:Heparin / Q000494:pharmacology; D004854:Herpesvirus 4, Human; D006801:Humans; D007163:Immunosorbent Techniques; D007700:Kinetics; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D011971:Receptors, Immunologic; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D015032:Zinc / Q000494:pharmacology; D017967:Zinc Compounds; D000099053:Histidine-Rich Glycoprotein
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D001798:Blood Proteins; D018801:CD2 Antigens; D002712:Chlorides; D006023:Glycoproteins; D011506:Proteins; D011971:Receptors, Immunologic; D017967:Zinc Compounds; D000099053:Histidine-Rich Glycoprotein; C016837:zinc chloride; D006493:Heparin; D015032:Zinc