Cytological and immunological changes in bronchoalveolar lavage fluid and histological observation of lung lesions in pigs immunized with Mycoplasma hyopneumoniae inactivated vaccine prepared from broth culture supernate

We have compared the cytology of bronchoalveolar lavage fluid (BALF) and th e pathology of lung lesions in pigs immunized with/without Mycoplasma hyopn eumoniae inactivated vaccine prepared from broth culture supernate on exper imental infection. Numbers of total cells, macrophages, neutrophils and lym phocytes have decreased in BALF of vaccinated pigs following infection. The mean percentage of lung lesions, inflammatory cell infiltration into the a irways and T cells accumulation around the bronchi were reduced in vaccinat ed pigs. The levels of tumor necrosis factor (TNF)-alpha also decreased in vaccinated pigs. These results suggest that the vaccination may contribute to decrease TNF-alpha production, and therefore, inflammatory cell response s in the lung due to M. hyopneumoniae infection were suppressed, resulting in fewer lung lesions. (C) 2000 Elsevier Science Ltd. All rights reserved.