Related Experiment Video
Updated: Mar 17, 2026
HPLC-based Assay to Monitor Extracellular Nucleotide/Nucleoside Metabolism in Human Chronic Lymphocytic Leukemia Cells
Published on: July 20, 2016
Correlation between Intracellular and Extracellular Lysozyme in Acute (Myelo)Monocytic Leukemia
1a The Third Department of Internal Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
Abstract:
The localization of myeloperoxidase (MPO) or lysozyme was studied in leukemic cells by electron microscopy in an attempt to investigate why the level of lysozyme activity increases in the serum of patients with acute (myelo)monocytic leukemia. The specimens were obtained from 3 patients with acute monocytic leukemia and 4 with acute myelomonocytic leukemia with extremely elevated serum lysozyme levels (more than 100 μg/ml, normal: ∼10µg/ml). The granules containing MPO or lysozyme, surrounded by microfilaments, were observed in the periphery of the cytoplasm. MPO positive granules were considered tot contain lysozyme. Some granules appeared to be degranulation from the cell-membrane of viable leukemic cells. This observation supports the concept that there is a mechanism by which lysozyme-positive granules degranulation from viable leukemic cells and as a result the level of lysozyme activity becomes elevated in the serum. It also appears that MPO is discharged into the serum at the same time as lysozyme: is released.
Insights
Elevated serum lysozyme in leukemia patients is linked to degranulation of lysozyme-positive granules from viable leukemic cells. Myeloperoxidase (MPO) is released concurrently with lysozyme.
Area of Science:
- Hematology
- Cell Biology
- Biochemistry
Background:
- Acute (myelo)monocytic leukemia is characterized by elevated serum lysozyme activity.
- The underlying mechanism for this increase in lysozyme levels remains unclear.
Purpose of the Study:
- To investigate the cellular localization of myeloperoxidase (MPO) and lysozyme in leukemic cells.
- To elucidate the mechanism behind elevated serum lysozyme in acute (myelo)monocytic leukemia.
Main Methods:
- Electron microscopy was used to examine leukemic cell specimens.
- Localization of MPO and lysozyme within leukemic cells was analyzed.
Main Results:
- Lysozyme and MPO were found in granules at the periphery of leukemic cell cytoplasm.
- Granules appeared to undergo degranulation from the cell membrane of viable cells.
- MPO-positive granules were identified as containing lysozyme.
Conclusions:
- Degranulation of lysozyme-positive granules from viable leukemic cells is a likely mechanism for elevated serum lysozyme.
- Myeloperoxidase (MPO) is co-released into the serum with lysozyme.
