Surfactant protein D. Increased accumulation in silica-induced pulmonary lipoproteinosis.
Surfactant protein D (SP-D) (CP4) is a collagenous surfactant-associated carbohydrate binding protein that is synthesized and secreted by alveolar epithelial cells. Previous studies have shown that intratracheal administration of crystalline silica to rats elicits a marked increase in the alveolar accumulation of surfactant lipids and surfactant protein A (SP-A). The authors examined the accumulation of SP-D using this animal model of alveolar proteinosis. Immunoperoxidase localization of SP-D studies at 2 weeks after silica instillation showed intense staining of intra-alveolar exudates, and cytoplasmic staining of hypertrophic type II cells. Immunoelectron microscopy showed that airspace SP-D was specifically associated with granular material, but not tubular myelin or other membranous structures. SP-D was quantified in bronchoalveolar lavage by immunoassay using antibodies specific for SP-D, and by reversephase HPLC after affinity purification of SP-D on maltosyl-agarose. Within 2 weeks after silica instillation, there was a greater than 45-fold increase in lavage SP-D per lung compared with saline controls, including an almost ten-fold increase in the insoluble or surfactant-associated protein. These studies indicate that the extracellular accumulation of SP-D is markedly increased in silica-induced lipoproteinosis, and that SP-D is associated with amorphous components identified by electron microscopy.
Crouch
E
E
Department of Pathology, Jewish Hospital, Washington University Medical Center, St. Louis, Missouri 63110.
Persson
A
A
Chang
D
D
Parghi
D
D
D000818:Animals; D000906:Antibodies / Q000276:immunology; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D004848:Epithelium / Q000378:metabolism / Q000648:ultrastructure; D006023:Glycoproteins / Q000032:analysis / Q000276:immunology / Q000378:metabolism*; D007124:Immunoenzyme Techniques; D008065:Lipoid Proteinosis of Urbach and Wiethe / Q000139:chemically induced / Q000378:metabolism*; D008171:Lung Diseases / Q000139:chemically induced / Q000378:metabolism*; D008854:Microscopy, Electron; D016253:Microscopy, Immunoelectron; D011650:Pulmonary Alveoli / Q000378:metabolism / Q000648:ultrastructure; D037663:Pulmonary Surfactant-Associated Protein D; D011663:Pulmonary Surfactants / Q000032:analysis / Q000276:immunology / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012822:Silicon Dioxide
D000906:Antibodies; D006023:Glycoproteins; D037663:Pulmonary Surfactant-Associated Protein D; D011663:Pulmonary Surfactants; D012822:Silicon Dioxide