Surfactant protein D. Increased accumulation in silica-induced pulmonary lipoproteinosis

Am J Pathol. 1991 Oct;139(4):765-76.


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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antibodies / immunology
  • Bronchoalveolar Lavage Fluid / chemistry
  • Chromatography, High Pressure Liquid
  • Epithelium / metabolism
  • Epithelium / ultrastructure
  • Glycoproteins / analysis
  • Glycoproteins / immunology
  • Glycoproteins / metabolism*
  • Immunoenzyme Techniques
  • Lipoid Proteinosis of Urbach and Wiethe / chemically induced
  • Lipoid Proteinosis of Urbach and Wiethe / metabolism*
  • Lung Diseases / chemically induced
  • Lung Diseases / metabolism*
  • Microscopy, Electron
  • Microscopy, Immunoelectron
  • Pulmonary Alveoli / metabolism
  • Pulmonary Alveoli / ultrastructure
  • Pulmonary Surfactant-Associated Protein D
  • Pulmonary Surfactants / analysis
  • Pulmonary Surfactants / immunology
  • Pulmonary Surfactants / metabolism*
  • Rats
  • Rats, Inbred Strains
  • Silicon Dioxide


  • Antibodies
  • Glycoproteins
  • Pulmonary Surfactant-Associated Protein D
  • Pulmonary Surfactants
  • Silicon Dioxide