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Reception-mediated phagocytosis of yeast by macrophage polykarions
I Felipe1, G M Oliveira-Castro
1Instituto de Biofísica Carlos Chagas Filho, Universidade Federal de Rio de Janeiro, Brasil.
Abstract:
1. The phagocytic capacity of polynuclear macrophages (PNM) produced by intraperitoneal implants in mice was analyzed and compared with that of the mononuclear macrophage (M luminal diameter). The ability of PNM and M luminal diameter to interiorize aldehyde-fixed Saccharomyces cerevisiae is described. 2. PNM containing two to five nuclei and M luminal diameter exhibited a similar time course of phagocytosis. The phagocytic index reached a plateau from 30 to 60 min after exposure to yeast. 3. Mannose, mannan extracted from yeast and horseradish peroxidase inhibited yeast phagocytosis by PNM and M luminal diameter subpopulations to a similar extent. 4. Amino sugars (glucosamine, N-acetylglucosamine, galactosamine and N-acetylgalactosamine) caused similar reductions in the phagocytic indices of PNM and M luminal diameter. 5. The presence of monosaccharides (glucose, galactose, fructose and mannitol) did not alter the phagocytic capacity of either type of phagocyte. 6. Neither opsonin-dependent ingestion of sheep red blood cells nor ingestion of aldehyde-fixed cells by PNM or M luminal diameter is affected by mannose, suggesting that these processes involve internalization pathways different from the mannose-hexosamine recognition system. 7. Trypsin sensitivity, temperature dependence and divalent cation requirements for PNM phagocytosis were comparable to those of the M luminal diameter. 8. The similarities of the PNM to their mononuclear precursors suggest that the mannose-hexosamine receptor was preserved after polykaryon formation.
Insights
Polynuclear macrophages (PNM) and mononuclear macrophages (M luminal diameter) show similar phagocytic capacity for yeast, indicating the mannose-hexosamine receptor is preserved after polykaryon formation.
Area of Science:
- Immunology
- Cell Biology
Background:
- Macrophages play a crucial role in the immune system through phagocytosis.
- Polynuclear macrophages (PNM) are multinucleated cells formed from mononuclear precursors.
- Understanding the functional similarities and differences between PNM and mononuclear macrophages is important for comprehending immune responses.
Purpose of the Study:
- To compare the phagocytic capacity of polynuclear macrophages (PNM) with mononuclear macrophages (M luminal diameter).
- To investigate the role of the mannose-hexosamine recognition system in yeast phagocytosis by these macrophage types.
- To determine if the mannose-hexosamine receptor is retained after polykaryon formation.
Main Methods:
- In vitro phagocytosis assays using aldehyde-fixed Saccharomyces cerevisiae and sheep red blood cells.
- Inhibition studies using mannose, mannan, horseradish peroxidase, amino sugars, and monosaccharides.
- Analysis of phagocytic index, time course, trypsin sensitivity, temperature dependence, and divalent cation requirements.
Main Results:
- PNM and M luminal diameter exhibited similar time courses and phagocytic indices for yeast internalization.
- Mannose, mannan, and amino sugars similarly inhibited yeast phagocytosis by both macrophage types.
- Mannose did not affect the ingestion of opsonized or non-opsonized sheep red blood cells, suggesting alternative internalization pathways.
- Functional characteristics like trypsin sensitivity and cation requirements were comparable between PNM and M luminal diameter.
Conclusions:
- The mannose-hexosamine recognition system is involved in yeast phagocytosis by both PNM and M luminal diameter.
- The mannose-hexosamine receptor appears to be preserved after the formation of polynuclear macrophages.
- PNM retain functional similarities to their mononuclear precursors, suggesting conserved phagocytic mechanisms.