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Epidermal immunocompetence in canine leishmaniasis
D Fondevila1, M Vilafranca, L Ferrer
1Department de Patologia i Productions Animals, Facultat de Veterinària, Universitat Autònoma de Barcelona, Spain.
Insights
Dogs with alopecic dermatitis show effective Leishmania control due to functional antigen-presenting cells. Nodular lesions indicate impaired immunity and parasite proliferation, suggesting prognostic value for canine leishmaniasis skin lesions.
Area of Science:
- Veterinary Dermatology
- Immunology
- Parasitology
Background:
- Cutaneous leishmaniasis involves complex host-parasite interactions.
- Epidermal antigen-presenting cells, including Langerhans cells (LC), play a crucial role in initiating immune responses.
- Assessing epidermal immunocompetence is vital for understanding disease progression in infected animals.
Purpose of the Study:
- To investigate the role of epidermal antigen-presenting cells in canine leishmaniasis.
- To correlate epidermal immunocompetence with clinical presentation and parasite load.
- To evaluate canine leishmaniasis skin lesions as a model for human cutaneous leishmaniasis.
Main Methods:
- Immunocytochemical analysis of skin lesions in 16 dogs with Leishmania infection.
- Evaluation of Langerhans cells (LC) and MHC class II-positive keratinocytes.
- Quantification of dermal macrophages, T cells, and Leishmania parasites.
Main Results:
- Alopecic dermatitis was associated with adequate LC and MHC II expression, mild T cell infiltration, and low parasite numbers.
- Nodular lesions lacked epidermal antigen-presenting cells, correlating with massive dermal infiltration of macrophages and parasites.
- Ulcerative lesions exhibited intermediate inflammatory patterns.
Conclusions:
- Dogs with alopecic dermatitis demonstrate effective Leishmania control, indicating a competent immune response.
- Impaired immune response and significant parasite presence characterize nodular lesions.
- Canine leishmaniasis skin lesions offer a valuable model for studying human cutaneous leishmaniasis progression.
Abstract:
The antigen-presenting cell function of the epidermis was investigated immunocytochemically in 16 dogs with different types of skin lesions induced by Leishmania infection. The degree of epidermal immunocompetence was evaluated according to the presence of Langerhans cells (LC) and keratinocytes expressing class II major histocompatibility complex (MHC II) molecules on the one hand, and the relative numbers of macrophages, T cells, and parasites in the dermis on the other, as described for human cutaneous leishmaniasis. In alopecic dermatitis, appropriate numbers of LC and MHC II-positive keratinocytes were shown to be associated with a mild T cell infiltration without significant numbers of parasites. By contrast, when the epidermis lacked antigen-presenting cells, as occurred in nodular lesions, macrophages and parasites massively infiltrated the dermis. Ulcerative lesions showed intermediate patterns of inflammation. These results suggest that dogs with alopecic dermatitis develop an effective control of the infection, whereas those with a generalized nodular disease mount an impaired immune response against the parasite. Skin lesions in dogs infected by Leishmania might not only have a prognostic value, but also represent a suitable model to study the natural course of human cutaneous leishmaniasis.