title: Human neutrophil laminin receptors: activation-dependent receptor expression.
abstract: Activated human polymorphonuclear leukocytes (PMN) isolated from peripheral blood specifically bind 125I-laminin after stimulation with phorbol 12-myristate 13-acetate (PMA) or f-Met-Leu-Phe (FMLP) at 37 degrees C. Changes in laminin receptor expression are stimulus dose dependent at both chemotactic (10(-10) M to 10(-6) M) concentrations of FMLP, and secretory (greater than 5 ng/ml) levels of PMA. In the presence of cytochalasin B (5 micrograms/ml), 10(-7) M FMLP activation stimulates specific laminin binding, with an apparent Kd = 3.9 X 10(-9) M and 6.47 X 10(5) binding sites/cell, reaching equilibrium within 10 min at 4 degrees C. This observed activation-dependent change in laminin receptor expression is not due to interference by endogenous laminin, because no fluorescein-visualized anti-laminin antibody bound to cells without added glycoprotein, regardless of the level of activation. Levels of neutrophil lysozyme release, which show a PMA dose dependence similar to that of receptor binding activity, suggest that granule-plasma membrane fusion may be significant during increases in receptor expression. A lack of receptor stimulation by PMA from a granule-deficient patient or in granule-depleted cytoplasts from normal donors additionally supports this hypothesis. Electroblot transfer and autoradiography of subcellular fractions from unstimulated PMN reveals the presence of a 68,000 dalton laminin-binding component in the secondary/tertiary granule (beta) fraction, which may represent an intracellular laminin receptor pool.
mesh_terms: D002451:Cell Compartmentation; D002634:Chemotaxis, Leukocyte; D005089:Exocytosis; D005455:Fluorescent Antibody Technique; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D007797:Laminin / Q000378:metabolism*; D008247:Lysosomes / Q000378:metabolism; D009504:Neutrophils / Q000378:metabolism*; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic / Q000378:metabolism* / Q000502:physiology; D017474:Receptors, Laminin; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D007797:Laminin; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic; D017474:Receptors, Laminin; D013755:Tetradecanoylphorbol Acetate