Aggregation and opsonization of type A but not type B Hemophilus influenzae by surfactant protein A.
The ability of surfactant protein A (SP-A) to aggregate and opsonize type a and b Hemophilus influenzae was investigated. Type a, but not type b, was aggregated by SP-A. Aggregation was maximal at 24 micrograms SP-A/ml and was Ca(2+)-dependent. Aggregation of type a was inhibited by D-glucosyl-BSA but not by high concentrations of monosaccharides (D-mannose, D-galactose, D-glucose, or L-fucose) or by sialic acid, purified type a capsular polysaccharide, or type IV collagen. In Western blots, 125I-labeled SP-A bound to the major outer membrane protein (putatively P2) of type a hemophilus by a Ca(2+)-dependent mechanism. This binding was competitively inhibited by excess unlabeled SP-A. 125I-labeled SP-A also bound to the major membrane protein of type b, but at less than 5% of the level observed for type a. SP-A did not bind to lipooligosaccharides of either type a or type b. SP-A increased association of type a, but not type b, hemophilus with alveolar macrophages. After opsonization with SP-A, type a hemophilus were killed by alveolar macrophages, as indicated by bactericidal assays and the release of soluble, radiolabeled products from leukocytes. It is concluded that SP-A aggregated and opsonized type a hemophilus, but not type b, possibly because SP-A bound to the P2 outer membrane protein of type a to a greater extent.
Department of Medicine, Veterans Affairs Medical Center, Lexington, Kentucky.
T B
TB
McNeely
J D
JD
Coonrod
D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001665:Binding Sites; D001667:Binding, Competitive; D015153:Blotting, Western; D002118:Calcium / Q000494:pharmacology; D002241:Carbohydrates / Q000737:chemistry / Q000494:pharmacology; D003094:Collagen / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000378:metabolism; D016676:Macrophages, Alveolar / Q000502:physiology; D009895:Opsonin Proteins / Q000494:pharmacology; D010587:Phagocytosis; D011510:Proteolipids / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D011817:Rabbits; D012709:Serum Albumin / Q000494:pharmacology; D013329:Structure-Activity Relationship
D001425:Bacterial Outer Membrane Proteins; D002241:Carbohydrates; D009895:Opsonin Proteins; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D012709:Serum Albumin; C025616:glucosylated serum albumin; D003094:Collagen; D004492:Edetic Acid; D002118:Calcium