Evidence for a protective role of pulmonary surfactant protein D (SP-D) against influenza A viruses

J Clin Invest. 1994 Jul;94(1):311-9. doi: 10.1172/JCI117323.


We tested the hypothesis that pulmonary surfactant-associated lectins--surfactant proteins A and D (SP-A, and -D)--contribute to initial protective mechanisms against influenza A viruses (IAVs). SP-D potently inhibited hemagglutination activity of several strains of IAV as well as causing viral aggregation. SP-D enhanced neutrophil binding of IAV and neutrophil respiratory burst responses to the virus. Neutrophil dysfunction resulting from IAV exposure was diminished when the virus was pre-incubated with SP-D. Each of these effects was mediated by the calcium-dependent carbohydrate-binding property of SP-D. Native SP-D preparations of both human and rat origin, as well as recombinant rat SP-D, had similar activity. SP-A also inhibited IAV hemagglutination activity. We have previously reported that related mammalian serum lectins (mannose-binding lectin [MBL] and conglutinin) have similar effects. SP-D was at least 10-fold more potent at causing hemagglutination inhibition than were SP-A or MBL. SP-D was shown to contribute to potent anti-IAV activity of human bronchoalveolar lavage fluid. These results suggest that SP-D--alone, and in conjunction with SP-A and phagocytic cells--constitutes an important component of the natural immune response to IAV infection within the respiratory tract.

Publication types

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

MeSH terms

  • Animals
  • Bronchoalveolar Lavage Fluid / chemistry
  • Carrier Proteins / pharmacology
  • Glycoproteins / pharmacology*
  • Hemagglutination / drug effects
  • Humans
  • Hydrogen Peroxide / metabolism
  • Influenza A virus / drug effects*
  • Mannose-Binding Lectins
  • N-Formylmethionine Leucyl-Phenylalanine / pharmacology
  • Neutrophils / drug effects
  • Pulmonary Surfactant-Associated Protein D
  • Pulmonary Surfactants / pharmacology*
  • Rats


  • Carrier Proteins
  • Glycoproteins
  • Mannose-Binding Lectins
  • Pulmonary Surfactant-Associated Protein D
  • Pulmonary Surfactants
  • N-Formylmethionine Leucyl-Phenylalanine
  • Hydrogen Peroxide