title: Validation of an immunoassay to measure plasminogen-activator inhibitor-1 concentrations in human saliva.
abstract: BACKGROUND
  We have previously shown that the concentrations of D-dimer are significantly elevated in saliva compared with plasma. Saliva offers several advantages compared with blood analysis. We hypothesised that human saliva contains plasminogen activator inhibitor-1 (PAI-1) and that the concentrations are not affected by the time of saliva collection. The aim was to adopt and validate an immunoassay to quantify PAI-1 concentrations in saliva and to determine whether saliva collection time has an influence in the measurement.
  
  
  METHODS
  Two saliva samples (morning and afternoon) from the same day were collected from healthy subjects (N = 40) who have had no underlying heart conditions. A customized AlphaLISA® immunoassay (PerkinElmer®, MA, USA) was adopted and used to quantify PAI-1 concentrations. We validated the analytical performance of the customized immunoassay by calculating recovery of known amount of analyte spiked in saliva.
  
  
  RESULTS
  The recovery (95.03%), intra- (8.59%) and inter-assay (7.52%) variations were within the acceptable ranges. The median salivary PAI-1 concentrations were 394 pg/mL (interquartile ranges (IQR) 243.4-833.1 pg/mL) in the morning and 376 (129.1-615.4) pg/mL in the afternoon and the plasma concentration was 59,000 (24,000-110,000) pg/mL. Salivary PAI-1 did not correlate with plasma (P = 0.812).
  
  
  CONCLUSIONS
  The adopted immunoassay produced acceptable assay sensitivity and specificity. The data demonstrated that saliva contains PAI-1 and that its concentration is not affected by the time of saliva collection. There is no correlation between salivary and plasma PAI-1 concentrations. Further studies are required to demonstrate the utility of salivary PAI-1 in CVD risk factor studies.
authors: The University of Queensland Diamantina Institute, The University of Queensland, Translational Research Institute, Princess Alexandra Hospital, Woolloongabba, Australia.
authors: Xi
authors: X
authors: Zhang
authors: Goce
authors: G
authors: Dimeski
authors: Chamindie
authors: C
authors: Punyadeera
mesh_terms: D000328:Adult; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007118:Immunoassay / Q000592:standards*; D008297:Male; D017395:Plasminogen Activator Inhibitor 1 / Q000032:analysis*; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D012463:Saliva / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D017395:Plasminogen Activator Inhibitor 1; D011933:Reagent Kits, Diagnostic; C051321:SERPINE1 protein, human