Intact pathogenic Mycoplasma hyopneumoniae at 100 mu g protein ml(-1) induced transcription of proinflammatory cytokines such as cyclooxygenase (COX)-2, tumor necrosis factor (TNF)-alpha, interleukin(IL)-1, IL-6 and inducible nitric oxide synthase (iNOS) in RAW 264.7 cells. After pretreatment with 50 mu g surfactin C/ml, purified from Bacillus subtilis, transcription of the COX-2, IL-1 beta, IL-6 and iNOS genes induced by M. hyopneumoniae was inhibited by 43%, 82%, 72% and 59%, respectively.