Phagocytosis of viable Candida albicans by alveolar macrophages: lack of opsonin function of surfactant protein A.
Surfactant protein A (SP-A) contributes to host defense by opsonizing microbial organisms for phagocytosis by alveolar macrophages (AM). The role of SP-A as opsonin for phagocytosis of Candida albicans was analyzed. AM in suspension exhibited no phagocytosis of nonopsonized yeast. This was not increased by SP-A, whether provided for preincubation of AM or yeast or present during coincubation. However, the engulfment of serum-opsonized yeast by AM in suspension was inhibited by SP-A. This inhibitory effect was mimicked by complement subcomponent C1q and concanavalin A but not by type IV collagen. SP-A did not interfere with phagocytosis of serum-opsonized yeast by adherent AM, monocytes, neutrophils, or peritoneal macrophages. SP-A lacks function as an opsonin for the phagocytosis of C. albicans by AM but interferes with binding of yeast to AM, inhibiting subsequent ingestion. The role of SP-A as an alveolar space opsonin may thus critically depend on the microbial species involved.
Rosseau
S
S
Department of Internal Medicine, Justus-Liebig-University, Giessen, Germany.
Guenther
A
A
Seeger
W
W
Lohmeyer
J
J
D000818:Animals; D002177:Candidiasis / Q000276:immunology*; D003094:Collagen / Q000494:pharmacology; D015922:Complement C1q / Q000494:pharmacology; D003208:Concanavalin A / Q000494:pharmacology; D005260:Female; D005434:Flow Cytometry; D016676:Macrophages, Alveolar / Q000276:immunology*; D017737:Macrophages, Peritoneal / Q000276:immunology; D008297:Male; D009000:Monocytes / Q000276:immunology; D009504:Neutrophils / Q000276:immunology; D009895:Opsonin Proteins / Q000097:blood / Q000276:immunology*; D010587:Phagocytosis / Q000276:immunology*; D011510:Proteolipids / Q000276:immunology* / Q000502:physiology*; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000276:immunology* / Q000502:physiology*; D011817:Rabbits
D009895:Opsonin Proteins; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D003208:Concanavalin A; D015922:Complement C1q; D003094:Collagen