Elevated plasma surfactant protein D (SP-D) levels and a direct correlation with anti-severe acute respiratory syndrome coronavirus-specific IgG antibody in SARS patients

Scand J Immunol. 2009 Jun;69(6):508-15. doi: 10.1111/j.1365-3083.2009.02245.x.


Pulmonary SP-D is a defence lectin promoting clearance of viral infections. SP-D is recognized to bind the S protein of SARS-CoV and enhance phagocytosis. Moreover, systemic SP-D is widely used as a biomarker of alveolar integrity. We investigated the relation between plasma SP-D, SARS-type pneumonia and the SARS-specific IgG response. Sixteen patients with SARS, 19 patients with community-acquired pneumonia (CAP) (Streptococcus pneumonia) and 16 healthy control subjects were enrolled in the study. Plasma SP-D and anti-SARS-CoV N protein IgG were measured using ELISA. SP-D was significantly elevated in SARS-type pneumonia [median (95% CI), 453 (379-963) ng/ml versus controls 218 (160-362) ng/ml, P < 0.05] like in patients with CAP. SP-D significantly correlated with anti-SARS-CoV N protein IgG (r(2) = 0.5995, P = 0.02). The possible re-emergence of SARS or SARS-like infections suggests a need for minimal traumatic techniques for following the alveolar compartment, e.g. during testing of antivirals. We suggest that monitoring systemic SP-D may be useful in monitoring the alveolar integrity in SARS-type pneumonia. The significant correlation between plasma SP-D and anti-SARS-CoV-specific antibodies support the role for SP-D in interlinking innate and adaptive immune pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Antibodies, Viral / blood*
  • Biomarkers / blood
  • Child
  • Child, Preschool
  • Coronavirus Nucleocapsid Proteins
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Humans
  • Immunoglobulin G / blood*
  • Male
  • Middle Aged
  • Nucleocapsid Proteins / immunology*
  • Pulmonary Surfactant-Associated Protein D / blood*
  • Recombinant Proteins / immunology
  • Reverse Transcriptase Polymerase Chain Reaction
  • SARS Virus / immunology
  • Severe Acute Respiratory Syndrome / immunology*


  • Antibodies, Viral
  • Biomarkers
  • Coronavirus Nucleocapsid Proteins
  • Immunoglobulin G
  • Nucleocapsid Proteins
  • Pulmonary Surfactant-Associated Protein D
  • Recombinant Proteins