Abstract
In order to elucidate the cause of markedly increased serum and urine lysozyme (muramidase) in patients with monocytic leukemia on the cellular basis, monocytes and neutrophils were compared on their hydrolytic enzyme contents and their characteristics. Both types of leukocytes were separated from normal human blood or from patients with monocytic leukemia by means of floatation in dense albumin, utilizing the difference in the specific gravity of both cell types. Equivalent lysozyme and acid phosphatase activities were found to be present in monocytes and neutrophils and very low or negligible activities of alkaline phosphatase in monocytes. The subcellular distributions of these enzymes were comparable in the pattern and specific activity in both cell populations and found to be associated with granules. The phagocytic rate and the readiness of release of lysozyme into the extracellular medium during phagocytosis were similar in both cell populations. Leukemic leukocytes, neutrophils and monocytes, showed lower hydrolase activities than normal counterparts, especially alkaline phosphatase being markedly suppressed in leukemic cells. The possibility was discussed that the mechanism for elevated lysozyme in serum and urine of patients with monocytic leukemia may be accounted for by the developmental potential of monocytes in extravascular sites into macrophages with marked increase in lysosomal enzymes, the relatively ready release of lysozyme from cells, and a stable nature of lysozyme.
