Specific binding of surfactant apoprotein SP-A to rat alveolar macrophages.
Surfactant protein A (SP-A) influences the function of alveolar macrophages in vitro. In this study the characteristics of the binding of 125I-labeled SP-A to rat alveolar macrophages has been investigated. The binding of SP-A to alveolar macrophages at 4 degrees C was saturable with half-maximal binding at a SP-A concentration of 4 micrograms/ml. Bound SP-A was rapidly displaced by an excess of unlabeled SP-A. The binding of labeled SP-A to the alveolar macrophages was blocked in a dose-dependent fashion by unlabeled SP-A, the collagen-like protein C1q and type V collagen but not by bovine serum albumin. These results suggest that a component of the interaction between SP-A and alveolar macrophages is mediated through the collagen-like domain of SP-A and that the characteristics of this interaction are consistent with there being a specific receptor for SP-A on the surface of alveolar macrophages.
Pison
U
U
Cardiovascular Research Institute, University of California, San Francisco 94143.
Wright
J R
JR
Hawgood
S
S
D000818:Animals; D001059:Apoproteins / Q000378:metabolism*; D001667:Binding, Competitive; D004305:Dose-Response Relationship, Drug; D008024:Ligands; D016676:Macrophages, Alveolar / Q000378:metabolism*; D009994:Osmolar Concentration; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000378:metabolism*; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism
D001059:Apoproteins; D008024:Ligands; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D011956:Receptors, Cell Surface; C046616:pulmonary surfactant apoprotein