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Metabolic activity of phagocytes in experimental sporotrichosis
Abstract:
Phagocytosis plays an important role as a protective mechanism against infections, since polymorphonuclear leukocytes (PMN) and macrophages are the first cellular lines opposed to aggressive microorganisms. In patients with sporotrichosis a diminished capability of killing engulfed yeast by their PMN has been described, but the origin of this deficiency remains unknown. In this work, partial aspects of the oxidative metabolism of PMN leukocytes and peritoneal macrophages of mongolian gerbils experimentally infected with sporotrichosis were studied. For this purpose the nitroblue tetrazolium (NBT) test as described by Baehner and Nathan (1) and myeloperoxidase activity measured according to Kaplow's method were utilized. The PMN and macrophages of mongolian gerbils infected with sporotrichosis showed increased reduction of NBT when compared with the phagocytic cells of normal ones, as is usually observed in most infections. Myeloperoxidase activity was diminished in both PMN and macrophages, but this diminution was statistically significant only in PMN leukocytes. These results show that part of the oxidative mechanisms of phagocytic cells can be impaired in experimental sporotrichosis, and could be correlated with the diminished fungicidal activity of PMN leukocytes obtained from patients infected with sporotrichosis.
Insights
Experimental sporotrichosis in gerbils revealed impaired oxidative metabolism in phagocytic cells. Polymorphonuclear leukocytes (PMN) showed diminished myeloperoxidase activity, potentially explaining reduced fungicidal capacity in infections.
Area of Science:
- Immunology
- Infectious Diseases
- Cellular Biology
Background:
- Phagocytosis by polymorphonuclear leukocytes (PMN) and macrophages is crucial for combating infections.
- Diminished yeast-killing ability by PMN in human sporotrichosis patients is documented, but its cause is unclear.
- Understanding the oxidative metabolism of phagocytic cells is key to explaining immune deficiencies in sporotrichosis.
Purpose of the Study:
- To investigate the oxidative metabolism of PMN and macrophages in gerbils experimentally infected with sporotrichosis.
- To correlate observed metabolic changes with the known diminished fungicidal activity in sporotrichosis.
Main Methods:
- Experimental infection of mongolian gerbils with sporotrichosis.
- Assessment of phagocytic cell oxidative metabolism using the nitroblue tetrazolium (NBT) test.
- Measurement of myeloperoxidase activity in phagocytic cells.
Main Results:
- Infected gerbils exhibited increased NBT reduction in PMN and macrophages compared to controls.
- Myeloperoxidase activity was reduced in both PMN and macrophages from infected gerbils.
- The reduction in myeloperoxidase activity was statistically significant specifically in PMN leukocytes.
Conclusions:
- Experimental sporotrichosis impairs oxidative mechanisms in phagocytic cells, including PMN and macrophages.
- Diminished myeloperoxidase activity in PMN may underlie the reduced fungicidal capacity observed in sporotrichosis patients.
- These findings highlight a potential cellular basis for immune dysfunction in experimental sporotrichosis.