Lysozyme

Lysozyme is a 14.4 kDa enzyme, commonly referred to as the “body’s own antibiotic” since it kills bacteria. Lysozyme is an enzyme that destroys bacterial cell walls by hydrolyzing the polysaccharide component of the cell wall. It is abundantly present in a number of secretions, including tears. This protein is present in cytoplasmic granules of the polymorphonuclear neutrophils (PMN) and released through mucosal secretions such as tears and saliva. They can also be found in high concentration in egg white.

Lysozyme stains myeloid cells, histiocytes, granulocytes, macrophages, and monocytes in human tonsil, colon and skin. It is an important marker that may demonstrate the myeloid or monocytic nature of Acute Leukemia. The restrictive nature of Lysozyme antibody staining suggests that Lysozyme may be synthesized predominantly in reactive histiocytes rather than in resting, unstimulated phagocytes. It has not been determined whether Lysozyme stains any other cell or tissue type. Lysozyme may aid in the identification of histiocytic neoplasias and large lymphocytes, as well as classifying lymphoproliferative disorders.

Lysozyme is a purified immunoglobulin fraction of rabbit antiserum that is filter sterilized and diluted in buffer pH 7.5, containing BSA and sodium azide as a preservative.

1. Morsky P, Clin Chim Acta. 1988;178:327-36
2. Krugliak L, et al. A J Hematol. 1986;21:99-109
3. Delaflor-Weiss E, et al. Acta Cytol. 1999;Nov-Dec;43(6):1124-1130

1. Cut and mount 3-4 micron formalin-fixed paraffin-embedded tissues on positive charged slides.
2. Air dry for 2 hours at 58° C.
3. Deparaffinize, dehydrate and rehydrate tissues.
4. Subject tissues to heat epitope retrieval using a suitable retrieval solution such as ImmunoDNA Retriever with Citrate (BSB 0020-BSB 0023) or EDTA (BSB 0030-BSB 0033).
5. Any of three heating methods may be used:
   • Electric Pressure Cooker
     Place standoff rack at base of pressure cooker. Add 1-2 inches of distilled water to the pressure cooker and turn heat to high, and incubate for 15 minutes. Open and immediately transfer slides to room temperature.
   • Water Bath Method
     Place tissues/slides in a pre-warmed staining dish or coplin jar containing the ImmunoDNA Retriever with Citrate or EDTA in a water bath set at 95°-99° C. Incubate for 30-60 minutes.
   • Conventional Steamer Method
     Place tissues/slides in a pre-warmed staining dish or coplin jar containing the ImmunoDNA Retriever with Citrate or EDTA in a Steamer, cover and steam for 30-60 minutes.
6. After heat treatment, transfer slides in ImmunoDNA Retriever with Citrate or EDTA to room temperature and let stand for 15-20 minutes.
7. Wash slides with IHC wash buffer or DI water.
8. Continue IHC staining protocol.