Effects of 4-ipomeanol on bovine alveolar macrophage function

The objective of this study was to determine whether 4-ipomeanol toxicosis in calves impairs alveolar macrophage functions important in pulmonary defense against infectious agents. Male Holstein calves were given either 4-ipomeanol (3 mg kg−1, i.v.) or vehicle (polyethylene glycol 400). Alveolar macrophages were recovered by pulmonary lavage 3 days later, and their capacities to phagocytose and kill E. coli, migrate toward zymosan-activated immune bovine serum, and produce interferon and interleukin-1 activity were evaluated in vitro. Alveolar macrophages recovered from 4-ipomeanol-treated calves had over a 70% decrease (p < 0.01) in chemotactic activity and over a 37% decrease (p < 0.005) in their capacity to phagocytose E. coli as compared to macrophages from control calves. Interleukin-1 activity in macrophages from 4-ipomeanol-treated calves tended to the higher than that from control calves, but the differences were not statistically significant (p = 0.06). 4-ipomeanol did not affect macrophage bactericidal activity or production of interferon. These results indicate that 4-ipomeanol suppresses select functions of alveolar macrophages in cattle that may be important in pulmonary defense against bacterial pathogens.