Anatomomopathological and immunohistochemical analyses of the spleen and lymph node of dogs seropositives for leishmaniasis in serological tests

Abstract

Canine leishmaniasis (CanL) is a zoonosis caused by the protozoan of the species Leishmania infantum. The spleen and lymph nodes undergo morphological changes during CanL. This research aimed to perform an anatomopathological and immunohistochemical study of these organs in dogs reactive to leishmaniasis in the Dual-path Platform chromatographic immunoassay (DPP®) and Enzyme Immunoabsorption Assay (ELISA). Twenty-seven dogs were evaluated for anatomopathological examination with 92.6% showing changes at gross evaluation, specially splenomegaly and lymphadenomegaly. All dogs showed changes in the spleen unrelated to the parasitic load, with granulomatous splenitis being the most severe change. Diffuse cortical and paracortical hyperplasia, and hyperplasia and hypertrophy of the medullary cords were observed in the lymph node. Amastigote forms of Leishmania spp. were found in the spleen and lymph node at histopathological and immunohistochemical evaluations, with good agreement between these evaluations (k = 0.55, p = 0.00124), but no difference was observed in the parasitic intensity of these organs at immunohistochemistry (p = 0.23). It was concluded that spleen and lymph node from dogs reactive to leishmaniasis on the DPP® and ELISA tests show histomorphological changes resulting from the disease, independent to the parasitic load, as well as these organs show similar parasitic load at immunohistochemical test.

Keywords:
amastigote; histopathology; immunostaining; Leishmania spp.; lymphoid tissue