A rapid and sensitive non-competitive avidin-biotin immuno-enzymatic assay for lysozyme

A non-competitive avidin-biotin immuno-enzymatic assay (NABA) for lysozyme is described. The assay was found to be more sensitive than a competitive assay with biotinylated lysozyme. The lower detection limit of NABA was 0.1 ng lysozyme/ml compared to 1 ng/ml for the competitive assay. The intra-assay and inter-assay coefficients of variation for NABA were 5.9 and 9.1%, respectively. The total time for NABA can be decreased (to less than 1 h) without influencing the detection limit or the analytical range. Serum lysozyme levels measured by NABA and the enzymatic assay in 32 samples showed a correlation coefficient of r = 0.97.