Study of ocular manifestations and humoral immune response in eyes of dogs with leishmaniasis

BACKGROUND: Ocular manifestations in dogs with leishmaniasis are frequent and complications in affected tissues can lead to blindness. Immune processes play a very important role in the pathogenesis of ocular inflammation. Therefore, the immunology of ocular manifestations in dogs with leishmaniasis remains complex and poorly understood. OBJECTIVES: Estimation and characterisation of ocular and periocular manifestations in dogs naturally infected with Leishmania infantum and investigation of the production site of specific anti‐Leishmania infantum IgG. METHODS: The present investigation used 53 confirmed dogs infected with Leishmania infantum, presenting ocular and periocular lesions, and 10 control non‐infected dogs. Complete macroscopic ophthalmic examination of eyelids and globes was performed. Both total and anti‐Leishmania infantum IgG antibodies were studied in sera and aqueous humour (AH) of all dogs by ELISA technique. A Goldmann–Witmer coefficient (C value) was calculated. RESULTS: The main ophthalmological findings were keratoconjunctivitis (71.7%; 38/53), hyperplasia of conjunctival lymphoid follicles (54.7%; 29/53), blepharitis (50.9%; 27/53) and uveitis (20.7%; 11/53). Ocular production of anti‐Leishmania infantum IgG was detected in 73.6% (39/53) of infected dogs. There was no correlation between the antibody levels in AH and sera of the same dog. The mean anti‐Leishmania infantum IgG in AH was higher in uveitis, followed by lesions affecting only the adnexa (p < 0.0001). The highest mean C values were observed for uveitis, conjunctivitis and keratitis. CONCLUSIONS: Our findings suggest that production of anti‐Leishmania IgG in dogs infected with Leishmania infantum with ocular manifestations begin in situ and follows by a transfer of antibodies from the bloodstream to the AH.