title: Assessment of surfactant protein A (SP-A) dependent agglutination.
abstract: BACKGROUND
  Monomers of the collectin surfactant associated protein-A (SP-A) are arranged in trimers and higher oligomers. The state of oligomerization differs between individuals and likely affects SP-A's functional properties. SP-A can form aggregates together with other SP-A molecules. Here we report and assess a test system for the aggregate forming properties of SP-A in serum and broncho-alveolar lavage samples.
  
  
  METHODS
  Anti-SP-A antibodies fixed to latex beads bound SP-A at its N-terminal end and allowed the interaction with other SP-A molecules in a given sample by their C-terminal carbohydrate recognition domain (CRD) to agglutinate the beads to aggregates, which were quantified by light microscopy.
  
  
  RESULTS
  SP-A aggregation was dependent on its concentration, the presence of calcium, and was dose-dependently inhibited by mannose. Unaffected by the presence of SP-D no aggregation was observed in absence of SP-A. The more complex the oligomeric structure of SP-A present in a particular sample, the better was its capability to induce aggregation at a given total concentration of SP-A. SP-A in serum agglutinated independently of the pulmonary disease; in contrast SP-A in lung lavage fluid was clearly inferior in patients with chronic bronchitis and particularly with cystic fibrosis compared to controls.
  
  
  CONCLUSIONS
  The functional status of SP-A with respect to its aggregating properties in serum and lavage samples can be easily assessed. SP-A in lung lavage fluid in patients with severe neutrophilic bronchitis was inferior.
authors.affiliation: Dr. von Haunersches Kinderspital, University of Munich, Lindwurmstr. 4a, D-80337 Munich, Germany.
authors.forename: Stefanie M
authors.initials: SM
authors.lastname: Heinrich
authors.forename: Matthias
authors.initials: M
authors.lastname: Griese
mesh_terms: D000293:Adolescent; D029481:Bronchitis, Chronic / Q000097:blood / Q000503:physiopathology; D018893:Bronchoalveolar Lavage; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003550:Cystic Fibrosis / Q000097:blood / Q000503:physiopathology; D005260:Female; D006801:Humans; D007223:Infant; D007841:Latex Fixation Tests / Q000379:methods*; D008297:Male; D037662:Pulmonary Surfactant-Associated Protein A / Q000097:blood / Q000502:physiology*; D055815:Young Adult
chemical_list: D037662:Pulmonary Surfactant-Associated Protein A