Lysozyme (muramidase) activity of leukocytes and exfoliated epithelial cells in the oral cavity

abstract – Lysozyme (muramidase) activity was determined in leukocytes and in exfoliated epithelial cells collected from the mobile mucus phase of the oral cavity. With the method adopted exfoliated epithelial cells could be separated from leukocytes with a contamination of less than 1 %. With microbiologic tests none of the epithelial cells examined showed lysozyme activity. But on biochemical assay a very low Ievel of activity was observed, just at the limits of sensitivity of the method used. This amount, 0.2 μg/106 cells (hen eggwhite lysozyme, HEL), may have been due to contamination with bacteria. The lysozyme activity of oral PMN leukocytes was 5.65 ± 1.64 μg/106 cells (HEL). The loss of activity as compared with the PMN leukocytes of blood was roughly proportional to the injuries observed in the cells. It is inferred that injured neutrophils release lysozyme, and that oral leukocytes are one of the sources of the lysozyme present in saliva.