Periostin serum level analysis

Human periostin was dosed in serum samples. The assay was performed by ELISA kit Human Periostin/OSF 2 of Aviscera Bioscience. The kit contains the necessary components required for the quantitative measurement of recombinant and natural human periostin/OSF 2 in biological samples employing sandwich ELISA format. The plate is pre-coated with antibody specific for Periostin able to capture the periostin in the standard and the samples. The periostin captured was detected by the addition of a further periostin specific biotinylated antibody and streptavidin-HPR with its specific substrate. It follows the emission of colorimetric signal directly proportional to the concentration of periostin in the sample. This signal was then measured by microplate spectrophotometer at 450 nm. A standard curve was established by plotting the log of the known concentrations of the standard dilution (x axis) versus the log of this corresponding O.D. (y-axis) and the log-log curve was generated for the calculation of periostin (ng/ml) in serum samples. The detection limit of the ELISA assay used to assess periostin levels was 2.0 ng/ml. The measurements were performed blindly by one of the authors (MI), and all investigators were never aware of the periostin levels over the year of observation.