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Fine structure and cytochemistry of the interaction between Fonsecaea pedrosoi and mouse resident macrophages
S R Farbiarz1, T U De Carvalho, C Alviano
1Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brasil.
Abstract:
The interaction between conidia of Fonsecaea pedrosoi and mouse resident peritoneal macrophages was observed by light microscopy and by scanning (SEM) and transmission (TEM) electron microscopy. The conidia first attached to the surface of the macrophage and were then ingested. Prolonged incubation of the macrophage cultures showed proliferation of intracellular fungi as well as those which remained attached to the macrophage surface. The conidia were ingested by a typical phagocytic process, with formation of a phagosome. Macrophage lysosomes were observed to fuse with the phagosomes by immunofluorescence microscopy of macrophages previously labeled with acridine orange, by TEM of thin sections of macrophages labeled with albumin-gold, and by ultrastructural localization of acid phosphatase within the phagosomes.
Insights
Fonsecaea pedrosoi conidia interact with mouse macrophages, undergoing ingestion and proliferation. Macrophage lysosomes fuse with phagosomes, indicating an immune response to the fungal pathogen.
Area of Science:
- Mycology
- Immunology
- Cell Biology
Background:
- Fonsecaea pedrosoi is a fungus causing chromoblastomycosis.
- Understanding fungal-macrophage interactions is crucial for host defense mechanisms.
Purpose of the Study:
- To investigate the interaction between Fonsecaea pedrosoi conidia and mouse peritoneal macrophages.
- To elucidate the cellular and subcellular events during this interaction.
Main Methods:
- Light microscopy
- Scanning electron microscopy (SEM)
- Transmission electron microscopy (TEM)
- Immunofluorescence microscopy
- Acridine orange staining
- Albumin-gold labeling
- Acid phosphatase cytochemistry
Main Results:
- Conidia attached to and were ingested by macrophages via phagocytosis.
- Intracellular and surface fungal proliferation was observed.
- Lysosomal fusion with phagosomes containing conidia was confirmed.
- Acid phosphatase activity localized within phagosomes indicated lysosomal involvement.
Conclusions:
- Macrophages phagocytose Fonsecaea pedrosoi conidia.
- Lysosomal fusion is a key mechanism in the macrophage's response to fungal invasion.
- Fonsecaea pedrosoi can proliferate both intracellularly and extracellularly within macrophage cultures.