Caracterização patológica e imuno-histoquímica das lesões de actinobacilose em bovinos

Abstract

Actinobacillosis is a not contagious infectious disease, usually chronic, and characterized by pyogranulomatous inflammatory reaction that occurs in cattle and is less common in sheep, pig, and horse. Soft tissues of head, mouth, and regional lymph nodes are affected. In this retrospective study, lesions suggestive of Actinobacillosis from 18 cases of anatomopathologic bovine samples were retrieved from the archives of Setor de Patologia Veterinária of Universidade Federal do Rio Grande do Sul, from January 1997 to May 2011. The lesions were classified histologically, evaluated by histochemistry, and immunohistochemistry (IHC) in order to standardize inflammatory infiltration. The most frequent histological findings were typical pyogranulomas of actinobacillosis contained radiating eosinophilic clubs surrounded by neutrophils, macrophages, lymphocytes and abundant fibrous connective tissue. Gram-negative coccobacillus bacteria were shown in all lesions by Gram stain. Abundant macrophages were immunopositive for CD68, especially epithelioid cells and multinucleated giant cells. In addition, a positive immunostaining for CD3 (T lymphocyte) was observed in proportion of 1:3 in lymphocyte inflammatory infiltration, while IHC for CD79αcy (B lymphocytes) was obtained in proportion of 2:3. These results indicated that B lymphocytes are the majority of lymphocyte in the inflammatory area.