Studies of the Composition and Structure of Serum Lipoproteins: Isolation, Purification, and Characterization of Very Low Density Lipoproteins of Human Serum*

Biochemistry ◽  
1965 ◽  
Vol 4 (3) ◽  
pp. 596-605 ◽  
Author(s):  
Anders Gustafson ◽  
Petar Alaupovic ◽  
Robert H. Furman
Keyword(s):  
Human Serum ◽  
Low Density Lipoproteins ◽  
Low Density ◽  
Serum Lipoproteins ◽  
Purification And Characterization ◽  
Very Low Density Lipoproteins ◽  
Composition And Structure

In chyloptysis, SP-A affects the clearance of serum lipoproteins entering the airways

1998 ◽  
Vol 274 (5) ◽  
pp. L737-L749 ◽  
Author(s):  
Antonella Alberti ◽  
Franco Ravenna ◽  
Daniela Quaglino ◽  
Maurizio Luisetti ◽  
Maurizio Muraca ◽  
...  
Keyword(s):  
Lavage Fluid ◽  
Surfactant Protein ◽  
Low Density Lipoproteins ◽  
High Density Lipoproteins ◽  
Low Density ◽  
Serum Lipoproteins ◽  
Very Low Density Lipoproteins ◽  
Lymphatic Circulation ◽  
Alveolar Surfactant ◽  
Exogenous Substances

Serum lipoproteins may enter the airways and appear in sputum (chyloptysis) when the lymphatic circulation is impaired by inflammation, neoplasia, or an abnormal proliferation of smooth muscle cells. While analyzing the bronchoalveolar lavage fluid of a patient with chyloptysis, we noticed that surfactant could not be separated from contaminating serum lipoproteins and speculated that lipoproteins might interact with surfactant components. To clarify this point we immobilized surfactant protein (SP) A on microtiter wells and incubated it with 125I-labeled very low density lipoproteins (VLDLs), low-density lipoproteins, and high-density lipoproteins. We found that SP-A binds lipoproteins. Studying in greater detail the interaction of SP-A with VLDLs, we found that the binding is time and concentration dependent; is inhibited by unlabeled lipoproteins, phospholipids, and antibodies to SP-A; is increased by Ca2+; and is unaffected by methyl α-d-mannopyranoside. Whole surfactant is a potent inhibitor of binding. Furthermore, we found that SP-A increases the degradation of VLDLs by alveolar macrophages and favors the association of VLDLs with alveolar surfactant. We conclude that SP-A influences the disposal of serum lipoproteins entering the airways and speculate that binding to alveolar surfactant might represent an important step in the interaction between exogenous substances and the lung.

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