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Antimicrobial Proteins, Page 1 of 2
< Previous page Next page > /docserver/preview/fulltext/10.1128/9781555817671/9781555812911_Chap18-1.gif /docserver/preview/fulltext/10.1128/9781555817671/9781555812911_Chap18-2.gifAbstract:
Antimicrobial proteins are widely distributed in host defense cells and secretions. Antimicrobial proteins are also abundant in the secretions of epithelia exposed to environmental microbes (e.g., in the skin, nose and bronchi, the mouth, and the surface of the eyes). Classical characterization of antimicrobial proteins usually requires their extraction from the tissues or cells of origin, followed by activity-guided purification to homogeneity. Some antimicrobial proteins are enzymes that lyse the protein, lipid, carbohydrate, or perhaps nucleic acid components of microbes. Lysozyme is widely distributed in animal tissues. In humans, high concentrations of lysozyme are present in the cytoplasmic granules of neutrophils and Paneth cells, and in cellular and secretory compartments of monocytes and macrophages. Mice lacking neutrophil elastase are susceptible to infections with gram-negative bacteria, and mice doubly deficient in neutrophil elastase and cathepsin G are susceptible to fungal infection with Aspergillus fumigatus and resistant to the endothelial injury seen in endotoxic shock, suggesting an important role for serprocidins in both host defense and its pathological consequences. Both epithelia and phagocytes secrete protease inhibitors, of which the secretory leukoprotease inhibitor (SLPI) is the most abundant. Granulysin and its fragments display a broad spectrum of activity against many bacteria including Mycobacterium tuberculosis, and the protein has also been shown to contribute to CD8 T-cell-mediated killing of the yeast Cryptococcus Neoformans.