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Fine structure and cytochemical study of the interaction between Fonsecaea pedrosoi and rat polymorphonuclear
S Rozental1, C S Alviano, W de Souza
1Instituto de Biofisca Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil. rozental@ibccf.biof.urfj.br
Abstract:
The induction of a granulomatous reaction is frequently observed in subcutaneous mycoses. Our previous studies demonstrated that Fonsecaea pedrosoi was able to survive and proliferate in tissue macrophages and that activated macrophages were fungistatic but not fungicidal. By contrast, our present studies revealed that neutrophils were able to kill F. pedrosoi cells in periods shorter than 20 min. Several phases of the interaction process were analysed by light and electron microscopy. The kinetic analysis demonstrated no significant difference during the first hour of F. pedrosoi-neutrophil interaction. Electron microscopy images showed that neutrophils readily associated with and killed extracellular fungi; however, few fungi were ingested. During this process the activation of respiratory burst took place as evaluated by light and electron microscopy. Cytochemical activity of acid and alkaline phosphatase was detected in low levels during the host cell parasite interaction.
Insights
Neutrophils rapidly kill Fonsecaea pedrosoi, a fungus causing subcutaneous mycoses, within 20 minutes. This contrasts with macrophages, which are only fungistatic against this fungal pathogen.
Area of Science:
- Medical Mycology
- Immunology
- Cell Biology
Background:
- Subcutaneous mycoses often trigger granulomatous reactions.
- Fonsecaea pedrosoi survives and multiplies within tissue macrophages.
- Activated macrophages exhibit fungistatic, not fungicidal, activity against F. pedrosoi.
Purpose of the Study:
- To investigate the interaction between neutrophils and Fonsecaea pedrosoi.
- To determine the fungicidal capacity of neutrophils against F. pedrosoi.
- To analyze the cellular and kinetic aspects of this host-pathogen interaction.
Main Methods:
- Light and electron microscopy were used to analyze the interaction phases.
- Kinetic analysis assessed the interaction over time.
- Evaluation of respiratory burst activation and cytochemical activity of phosphatases.
Main Results:
- Neutrophils effectively killed extracellular F. pedrosoi within 20 minutes.
- No significant difference in interaction was observed during the first hour.
- Neutrophils showed association with and killing of fungi, with limited ingestion.
- Activation of the respiratory burst was observed during neutrophil-fungi interaction.
- Low levels of acid and alkaline phosphatase activity were detected.
Conclusions:
- Neutrophils possess potent fungicidal activity against Fonsecaea pedrosoi.
- The respiratory burst is a key mechanism in neutrophil-mediated killing of F. pedrosoi.
- Neutrophils represent a crucial component of the innate immune response against subcutaneous mycoses caused by F. pedrosoi.