Granulomatous lesions including lepromatous and tuberculoid types observed in bovine intestines infected with Mycobacterium paratuberculosis, were examined immunohistochemically. The deposition of a cytokine TNF-alpha was mainly confined to the cytoplasm of epithelioid cells and Langhans'-type giant cells containing many acid-fast bacteria in lepromatous type lesions. Compared with tuberculoid type lesions, CD4 positive cells in lepromatous type lesions were fewer. Typical clinical signs were observed in cattle with typical lepromatous type lesions. The inhibition of cellular immunity in bovine paratuberculosis would thus appear be to TNF-alpha and decrease in CD4 positive T cells.
(Second Lab. of Pathology, Third Research Division)