Cytokine expression in lungs of calves spontaneously infected with Mycoplasma bovis

Cytokine expression in the lung can play an important role during Mycoplasma bovis infection through leukocyte recruitment and activation, and the induction of a broad array of inflammatory mediators. To gain further insight into the pathogenesis of M. bovis-associated pneumonia, cytokine expression was examined, by immunohistochemical methods in formalin-fixed, paraffin wax-embedded tissues, in the lung of 20 calves spontaneously infected. Immunolabelling for tumor necrosis factor alpha (TNF)-α, interleukin-4 (IL-4), IL-10 and interferon-gamma (IFN-γ), was usually associated with pneumonia, particularly in macrophages and lymphocytes, and with the presence of M. bovis antigen. The expression was minimal in lungs from negative controls. The results demonstrated consistent upregulation of TNF-α, IL-4, IL-10 and IFN-γ expression during M. bovis-associated pneumonic lesions. These cytokines can participate in the immune and inflammatory responses during the pulmonary defense mechanisms against M. bovis infection.