Serum lysozyme and inflammatory bowel disease1
Thirty-five patients with Crohn's disease and six patients with ulcerative colitis had elevated serum lysozyme levels compared with 47 normals, but there was no diagnostic difference in serum lysozyme levels between the two diseases. Patients with Crohn's disease were grouped according to the location of the disease: the small intestine, ileocolon, and colon. The distribution of serum lysozyme levels for normals and the distribution of levels for the three groups of patients with Crohn's disease and the group with mucosal ulcerative colitis overlapped by about one standard deviation. In addition, no substantial serum lysozyme differences were observed among the three groups of patients with Crohn's disease. Human serum lysozyme was considerably more active than the standard egg white lysozyme, and the relationship between the activities of the two lysozymes and their concentrations was linear only between 0 μg/mL and 1 μg/mL. Differences between human serum and egg white lysozyme activity may explain some of the conflicting reports in the literature. Because the manufacturer has discontinued the lysozyme turbidimetric kit, the authors provide a detailed description of the method. There were significant correlations between two lysoplate methods and between the Worthington lysoplate method and one turbidimetric method, but not between the turbidimetric method and the Kallested radial diffusion assay method.