Immunochemical determination of human lysozyme by laser nephelometry

The methods currently available for quantitative determination of lysozyme are based on the capacity of the enzyme to lyse Micrococcus lysodeikticus. Previous attempts to develop immunochemical assays have been reported, but the sensitivity was inferior to that of the most widely used lysoplate method. We describe the development of a sensitive immunochemical method for lysozyme assay in which the recently developed laser nephelometer is used. The sensitivity so achieved is at least comparable to that of the lysoplate method, and in some circumstances better. Results obtained by the lysoplate assay and the nephelometric assay correlate well. Among the advantages of our method are easier handling of larger numbers of samples, quicker results, and the possibility of assaying enzymatically inactive forms of the enzyme.