Soluble CD 40 Ligand Measurement Inaccuracies Attributable to Specimen Type , Processing Time , and ELISA Method

receiving oral enzyme replacement therapy, which is a major drawback for the clinical application of the pET. On the other hand, the antigenic substrate in the pET seems to be equally stable in relation to elastase 1. Only elastase concentrations determined with the pET in stools stored at 4 °C for 48 h were significantly higher than directly measured concentrations. Although both pET and mET assessments were performed on stool samples stored in continuously closed cups, partial evaporation with consecutive concentration of the substrate cannot be excluded. If we take into consideration the different aspects of fecal elastase testing highlighted in this study, the lack of specificity of the pET assay remains the crucial problem. We therefore support the proposal of renaming the polyclonal “elastase 1” ELISA because the test detects a molecule different from elastase 1 (7 ). Further studies should evaluate the effects of porcine enzymes on the results of the pET assay in patients with normal and mildly to moderately decreased exocrine pancreatic function. Additionally, the true antigen detected with the pET assay should be characterized to reliably define the role of this new assay in the diagnosis of exocrine pancreatic insufficiency.