Fast and Quantitative Evaluation of Human Leukocyte Interaction with Aspergillus fumigatus Conidia by Flow Cytometry

Area of Science:

• Immunology
• Medical Mycology
• Flow Cytometry

Background:

• Systemic infections by Aspergillus fumigatus pose a significant risk to immunocompromised individuals, including transplant recipients.
• Understanding the phagocytosis of fungal conidia by human phagocytes is crucial for immunological research on A. fumigatus.
• Existing methods for analyzing phagocytosis can be limiting.

Purpose of the Study:

• To develop and present a rapid and adaptable flow cytometry assay for quantifying Aspergillus fumigatus conidia phagocytosis.
• To enable simultaneous analysis of phagocytosis and cell surface markers.
• To investigate phagocytosis rates across different fungal developmental stages and incubation times.

Main Methods:

• Fluorescein isothiocyanate (FITC) labeling of A. fumigatus conidia before co-incubation with human leukocytes.
• Utilizing an anti-FITC counterstaining step post-incubation to differentiate between internalized and adherent conidia.
• Employing flow cytometry for quantitative analysis.

Main Results:

• The developed method allows for fast and flexible analysis of phagocytosis.
• The assay successfully distinguishes between internalized and adherent conidia.
• The protocol is compatible with additional surface marker analyses, enhancing its utility.
• Phagocytosis rates were determined for different fungal stages and incubation periods.
• A comparison of phagocytosis between wild-type and mutant A. fumigatus strains was successfully demonstrated.

Conclusions:

• This novel flow cytometry method provides an efficient and versatile tool for studying Aspergillus fumigatus phagocytosis.
• The technique facilitates a deeper understanding of host-pathogen interactions in immunocompromised patients.
• The ability to combine phagocytosis assays with surface marker analysis opens new avenues for immunological research.