Severe feline sporotrichosis associated with an increased population of CD8^lowcells and a decrease in CD4⁺cells

Abstract

Sporotrichosis is a subcutaneous mycosis with worldwide distribution, especially in tropical and subtropical areas. Zoonotic transmission is described with cats being the main animal species involved. The occurrence of severe feline sporotrichosis with high fungal levels demonstrates the susceptibility of cats to this disease and the importance of studying its pathogenesis. This study describes the leukocytes profile in blood of cats with sporotrichosis by flow cytometry and its correlation with histopathology and fungal load. The cats with sporotrichosis were separated into groups L1, L2, and L3 (lesions at one, two, and three or more noncontiguous skin locations, respectively) and were classified as good, fair, or poor general conditions. The highest percentage of CD4+ cells was associated to L1 (P = .04) and to good general condition (P = .03). The percentage of CD8+ cells was greater in L2 and L3 (P = .01). CD8(low) expression occurred in 20 animals with sporotrichosis, mainly in L3 (P = .01) and was not observed in healthy controls. This expression was related to macrophage granulomas (P = .01) and predominated in cases with high fungal load. Altogether, the results indicated that control over feline sporotrichosis, with maintenance of a good general condition, fixed lesions, well-organized response and lower fungal load, is associated with increased CD4+ cells percentages. In contrast, a poor general condition, disseminated lesions and high fungal load were related to increased CD8+ cell percentages and increased expression of CD8(low). As conclusion these results point to an important role of the CD4:CD8 balance in determining the clinical outcome in feline sporotrichosis.

Immunophenotypic characterization and clinical outcome in cats with lymphocytosis

“…Neoplastic changes resulting in the loss of surface molecule expression are relatively common in lymphomas and leukemias, but the origin of this DN population in non‐neoplastic states is less clear. We frequently identify a small population of CD8 low T cells in cat blood as has been reported by others, but after accounting for these, a true DN T‐cell population still is detected. One possibility for a lymphocyte expressing CD5 or CD3 but lacking CD4/CD8 expression would be γδT cells.…”

Comparison of two in vitro antifungal sensitivity tests and monitoring during therapy of Sporothrix schenckii sensu stricto in Malaysian cats

“…Cats with sporotrichosis have been observed to have an inversion of the CD4/CD8 peripheral circulating lymphocyte ratio; infection was associated with greater percentages of CD8+ cells, and especially of CD8 low cells, in cases where clinical signs were more severe . This observation supports the view that the host immune response is a key factor that may hinder complete cure, despite correct medication and sensitivity of the microorganism to the antimicrobial therapy.…”

Zoonotic Epidemic of Sporotrichosis: Cat to Human Transmission

“…However, most cats with sporotrichosis display lesions with poorly-formed granulomas and high fungal burden, which generally correlated with CD8 low cell subsets [28]. Interestingly, this subset is referred to as greatly enhanced by a Th2-shifted environment [29], while the host protective immunity to fungal infections seems to rely largely on a Th1-biased response [30].…”

“…Thus, the direct inoculation of yeast could lead to more challenging host–pathogen interactions and be crucial for the establishment of the infection. We speculate that the evasion of the yeast cells could take part in the typical development of lesions [28] with macrophages apparently unable to complete phagocytosis in feline sporotrichosis and prevent further activation of adaptive immunity. Fungal wall compounds are also important in the adhesion to extracellular matrix, in particular 3-carboxymuconate cyclase (glycoprotein Gp70 and Gp60) [39–40].…”