Some of the immunopathogenic aspects of the uveitis in natural and experimental occurrence of canine ehrlichiosis: anatomopathological and immunohistochemical analyses

Author(s)

Valérie Le Du da Silva

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2006-06-23

Examining board members

José Luiz Guerra; Mirela Tinucci Costa; Maria Lucia Zaidan Dagli; Rosangela Zacarias Machado; Idercio Luiz Sinhorini

• Advisor: José Luiz Guerra

Abstract

The immunopathogenicity of uveitis in the canine ehrlichiosis was studied by conducting anatomy and immunohistochemical analyses in the ocular globes of dogs experimentally (Group 1) and naturally (Group 2) infected with Ehrlichia canis, and naturally coinfected with Ehrlichia canis and Babesia sp. (Group 3). Clinical and hematological parameters were evaluated. Dot-blot Elisa and indirect immunofluorescent test (IFA) were used to analyze E. canis and Babesia sp., respectively. PCR assay confirmed the diagnosis of the disease caused by E. canis. The immunophenotypic analysis with the antibodies CD3, CD4, CD8, Tal1B5 and MAC 387 revealed no significant differences between the various ocular regions analyzed. Significant differences were observed between the immunophenotypic analysis of CD8+ and CD4+cells from all regions analyzed from G1, G2 and G3; between the percentile counts of IgG2+ and CD79?+ in the ciliary body of G3 dogs when compared to G1, and for the IgG1 antibody counts of the iris region from G3 when compared to G2. A linear correlation between CD3+ and CD8+ cells and between IgG2+ and CD79?+ cells from several regions of the ocular globe was found for all three groups. The cellular inflammatory infiltrate observed in the ocular tissue was severe in the regions of the ciliary bodies and iridocorneal angle, moderate in the limbus and iris, and only slightly present in the choroids. A semiquantitative analysis of the intensity of the inflammatory infiltrate of the ocular globes was more intense in G3, which suggested a greater response of the immune system in these animals. The inflammatory infiltrate was composed of mainly B CD79+? and T CD3+ lymphocytes, which had CD8+ at a high percentage, thus characterizing this as a cytotoxic immune response. Results indicated that B CD79+? cells favored the production of local antibodies. IgG2 and very few IgG1 immunolabeled cells were found. This result indicated a polarization of the immune response to the Th1 pattern, which could be the mechanism of the lesions in the uveitis. A large number of cells expressing the MHC-class II molecules were observed, suggesting an intense immune response in the ocular tissues, however ineffective due to the CD4+ cell´s deficient. (AU)