Development of a sensitive enzyme-linked immunosorbent assay for measurement of DNase I in human serum.

BACKGROUND: Serum deoxyribonuclease I (DNase I) activity was reported to increase in the early phase after onset of acute myocardial infarction (AMI). Up to now, DNase I activity has been quantified by the single radial enzyme diffusion (SRED) method, which unfortunately requires a long incubation time. Therefore it is necessary to develop another assay suitable for measurement of serum DNase I concentrations in a clinical setting. METHODS: A sandwich ELISA was established for measurement of DNase I protein using a polyclonal antibody directed against DNase I protein and a biotinylated monoclonal for subsequent detection. Concentrations of serum DNase I protein were measured in healthy individuals and patients with AMI. RESULTS: This method was as precise as SRED, and took less time than SRED. A significant correlation was observed between DNase I concentration and enzyme activity (r=0.839; P<0.001). The average of serum DNase I in AMI patients within 0-12 h of chest pain was significantly higher than that in healthy individuals (P<0.001), and decreased with time. CONCLUSIONS: We have developed a sensitive ELISA capable of measuring DNase I protein concentrations. This method may be a useful alternative to SRED as an aid to diagnosis of AMI based on the serum DNase I level.