title: Binding of vasoactive intestinal polypeptide (VIP) by human blood monocytes: demonstration of specific binding sites.
abstract: Vasoactive intestinal polypeptide (VIP) interaction with a 94% pure preparation of monocytes isolated from human peripheral blood was studied by direct binding technique using 3-[125I]tyrosyl-VIP as a tracer ligand. Scatchard analysis of binding data was compatible with two classes of binding sites, one with Kd = 0.25 nM and maximal binding capacity of 16 fmol/10(6) cells, and another one with Kd = 25 nM and maximal binding capacity of 180 fmol/10(6) cells. The binding was time-, temperature-, and pH-dependent and was saturable, reversible, and specific. This study has demonstrated that human monocytes have high affinity/low capacity as well as low affinity/high capacity binding sites for VIP. No specific VIP binding was found in pure preparations of human granulocytes, platelets or erythrocytes.
mesh_terms: D000328:Adult; D001667:Binding, Competitive; D001792:Blood Platelets / Q000378:metabolism; D002469:Cell Separation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009000:Monocytes / Q000166:cytology / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018005:Receptors, Vasoactive Intestinal Peptide; D013816:Thermodynamics; D014660:Vasoactive Intestinal Peptide / Q000097:blood*
chemical_list: D011956:Receptors, Cell Surface; D018005:Receptors, Vasoactive Intestinal Peptide; D014660:Vasoactive Intestinal Peptide