Serum lysozyme measurement is used with other laboratory tests to diagnose acute myelocytic leukemia or other leukemias, sarcoidosis, and tuberculosis.
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Lysozyme, or muramidase, is found in various bodily fluids, including blood serum. It plays a crucial role as a natural antimicrobial agent in the body's innate immune system. Lysozyme was first discovered in human tears by Alexander Fleming in 1922. Lysozyme is a small protein consisting of 129 amino acids.
Lysozyme is an enzyme that catalyzes the hydrolysis of peptidoglycan, a major component of bacterial cell walls. By breaking down this structure, lysozyme disrupts the bacterial cell wall, leading to the lysis and death of bacteria. This activity helps protect the body against bacterial infections.
While lysozyme is found in various bodily secretions such as tears, saliva, mucus, and breast milk, it is also in serum at lower concentrations. Multiple factors, including genetics, inflammation, and certain diseases, influence serum lysozyme levels. Besides its antimicrobial properties, lysozyme has other physiological roles. It acts as a digestive enzyme in the gastrointestinal tract, aiding the breakdown of bacterial cell walls in ingested food. Lysozyme also plays a role in tissue remodeling and repair, as well as the regulation of the gut microbiota.
Low levels of serum lysozyme may be associated with immunodeficiency conditions.
Serum lysozyme levels can increase in response to various factors and medical conditions.
- Inflammatory conditions: Serum lysozyme levels can rise in response to inflammation. Inflammatory disorders such as sarcoidosis, rheumatoid arthritis, and inflammatory bowel disease (e.g., Crohn's disease and ulcerative colitis) have been associated with increased serum lysozyme levels.
- Infections: Certain bacterial infections can lead to an increase in serum lysozyme levels.
- Cancers: Elevated serum lysozyme levels have been linked to some cancers, particularly hematological malignancies such as leukemia and lymphoma. However, the underlying mechanisms are not well-defined, and the clinical significance of this elevation is still being investigated.
- Other conditions: Serum lysozyme levels may also increase in certain renal disorders, such as chronic kidney disease. Additionally, situations that involve tissue damage, such as myocardial infarction or severe burns, can cause a transient increase in serum lysozyme levels.
Elevated serum lysozyme levels alone are not diagnostic of a specific condition. They are typically considered in conjunction with other clinical and laboratory findings to aid in diagnosing and monitoring certain diseases.
