Severe feline sporotrichosis associated with an increased population of CD8low cells and a decrease in CD4⁺ cells

Area of Science:

• Veterinary Mycology
• Immunology
• Feline Infectious Diseases

Background:

• Sporotrichosis is a fungal infection affecting cats worldwide, with zoonotic potential.
• Severe cases in cats highlight the need to understand disease pathogenesis.
• Cats are a significant animal reservoir for Sporothrix species.

Purpose of the Study:

• To analyze leukocyte profiles in cats with sporotrichosis using flow cytometry.
• To correlate these profiles with histopathology and fungal load.
• To understand the role of immune cell balance in feline sporotrichosis outcomes.

Main Methods:

• Flow cytometry was used to analyze blood leukocytes in cats with sporotrichosis.
• Cats were categorized by lesion number (L1, L2, L3) and general condition (good, fair, poor).
• Leukocyte profiles were correlated with histopathological findings and fungal burden.

Main Results:

• Higher CD4+ cell percentages were linked to fewer lesions (L1) and good general condition.
• Increased CD8+ cell percentages were observed in cats with more lesions (L2, L3).
• CD8(low) expression, associated with macrophage granulomas and high fungal load, was found in severe cases.

Conclusions:

• A favorable clinical outcome in feline sporotrichosis is associated with higher CD4+ cell percentages.
• Disseminated lesions and high fungal load correlate with increased CD8+ cells and CD8(low) expression.
• The CD4:CD8 balance is crucial in determining the clinical outcome of feline sporotrichosis.