Pulmonary surfactant proteins A and D enhance neutrophil uptake of bacteria.
The collectins are a class of collagenous lectin proteins present in serum and pulmonary secretions [pulmonary surfactant protein (SP) A and SP-D] that are believed to participate in innate immune responses to various pathogens. With the use of flow cytometric and fluorescent-microscopic assays, SP-A and SP-D were shown to increase calcium-dependent neutrophil uptake of Escherichia coli, Streptococcus pneumoniae, and Staphylococcus aureus. Evidence is provided that the collectins enhanced bacterial uptake through a mechanism that involved both bacterial aggregation and direct actions on neutrophils. The degree of multimerization of SP-D preparations was a critical determinant of both aggregating activity and potency in enhancing bacterial uptake. The mechanisms of opsonizing activity of SP-D and SP-A differed in important respects from those of opsonizing antibodies. These results provide the first evidence that surfactant collectins may promote neutrophil-mediated clearance of bacteria in the lung independently of opsonizing antibody.
Hartshorn
K L
KL
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
Crouch
E
E
White
M R
MR
Colamussi
M L
ML
Kakkanatt
A
A
Tauber
B
B
Shepherd
V
V
Sastry
K N
KN
D000818:Animals; D001419:Bacteria / Q000187:drug effects / Q000378:metabolism; D001770:Blood Bactericidal Activity; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D046911:Macromolecular Substances; D009504:Neutrophils / Q000502:physiology*; D009895:Opsonin Proteins; D010587:Phagocytosis; D011510:Proteolipids / Q000378:metabolism / Q000494:pharmacology*; D037662:Pulmonary Surfactant-Associated Protein A; D037663:Pulmonary Surfactant-Associated Protein D; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects / Q000378:metabolism; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000378:metabolism
D006023:Glycoproteins; D046911:Macromolecular Substances; D009895:Opsonin Proteins; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037663:Pulmonary Surfactant-Associated Protein D; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D011994:Recombinant Proteins