Immunohistochemical detection of cyclooxygenase-2 in lungs of pigs naturally infected with Actinobacillus pleuropneumoniae

Cyclooxygenase-2 (COX-2) protein was detected immunohistochemically in formalin-Fixed, paraffin wax- embedded lung tissues from 15 pigs with naturally occurring pleuropneumonia caused by Actinobacillus pleuropneumoniae. Positive cells typically exhibited a red reaction product without background staining. Alveolar macrophages, neutrophils, and bronchial and bronchiolar epithelial cells had positive immunohistochemical signals. Immunoreactivity of COX-2 protein was intense in the clustered leucocytes with streaming nuclear chromatin that are a characteristic histological feature of porcine pleuropneumonia. COX-2 protein was always associated with macrophages and neutrophils in pleuropneumonic lung lesions but was minimal in non-lesional lung of A. pleuropneumoniae-infected pigs and in normal lung from control pigs. The results suggest that COX-2 plays a role in pathophysiological processes during A. pleuropneumoniae infection. (C) 2002 Elsevier Science Ltd. All rights reserved.