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Cytolytic plasma factor in experimental coccidioidomycosis
Abstract:
Peripheral blood leukocytes from guinea pigs infected with Coccidioides immitis 5 weeks previously were lysed significantly when incubated at 37 C for 3.5 hr with a concentrated C. immitis culture filtrate, but not with a concentrated Aspergillus fumigatus or Blastomyces dermatitidis culture filtrate. Mononuclear leukocytes and presumably granulocytes were both lysed. Characterization of the factor responsible for this leukocytolysis reaction revealed that it was contained in plasma and serum but not in leukocytes from infected guinea pigs. It was complement-dependent, active after heating at 56 C, and stable after storage at -20 C for as long as 14 months.
Insights
Infected guinea pigs showed significant leukocytolysis when exposed to Coccidioides immitis filtrate. This complement-dependent reaction involved plasma factors and was stable, indicating a specific immune response to the fungal infection.
Area of Science:
- Immunology
- Mycology
- Infectious Diseases
Background:
- Coccidioides immitis is a fungal pathogen causing coccidioidomycosis.
- Immune responses to fungal infections involve various leukocyte populations.
- Understanding host-pathogen interactions is crucial for developing treatments.
Purpose of the Study:
- To investigate the effect of Coccidioides immitis culture filtrate on peripheral blood leukocytes from infected guinea pigs.
- To characterize the factor responsible for observed leukocytolysis.
Main Methods:
- Incubation of guinea pig leukocytes with fungal culture filtrates (C. immitis, A. fumigatus, B. dermatitidis).
- Assessment of cell lysis at 37°C for 3.5 hours.
- Characterization of the leukocytolytic factor's presence in plasma, serum, and leukocytes, and its stability and complement dependence.
Main Results:
- Significant lysis of peripheral blood leukocytes from C. immitis-infected guinea pigs upon incubation with C. immitis culture filtrate.
- No lysis observed with Aspergillus fumigatus or Blastomyces dermatitidis culture filtrates.
- Leukocytolysis was mediated by plasma/serum factors, was complement-dependent, heat-stable (56°C), and remained stable for 14 months at -20°C.
Conclusions:
- A specific, complement-dependent factor in the plasma/serum of C. immitis-infected guinea pigs causes leukocytolysis.
- This factor targets both mononuclear leukocytes and granulocytes.
- The findings suggest a specific immune mechanism involved in the host response to Coccidioides immitis infection.