Immunochemical determination of human tear lysozyme (muramidase) in keratoconjunctivitis sicca

Radial immunodiffusion was tested as an alternative for the agar diffusion assay for lysozyme in tear fluid. The influence of interactions between lysozyme and agarose or filter paper, used for sample collection, on the results of the immunodiffusion test was investigated. In 100 tear samples from 50 healthy volunteers and average lysozyme concentration of 1.9 g/l was found. Lysozyme values obtained by both methods in the tear fluid of a group of 78 volunteers, ranging from healthy individuals to severe keratoconjunctivitis sicca patients were compared. A lower limit of normal at 1.1 g/l was found by the radial immunodiffusion assay.