V. Boulanger et al., Induction of nitric oxide production by bovine mammary epithelial cells and blood leukocytes, J DAIRY SCI, 84(6), 2001, pp. 1430-1437
A recent study from our laboratory has shown that significant amounts of ni
tric oxide are released by somatic cells recovered during endotoxin-induced
mastitis. The present study was undertaken to investigate which cell type(
s) among milk somatic cell population can produce nitric oxide under inflam
matory conditions. Nitric oxide release from mammary epithelial cell lines
and from bovine neutrophils and monocytes extracted from blood was measured
in response to cytokines and Escherichia coli lipopolysaccharides. An epit
helial cell line isolated from bovine mammary gland, FbE cells, was found t
o release nitric oxide after exposure to interleukin-1 beta. This nitric ox
ide production was completely abolished by addition of L-N-6-(1-iminoethyl)
lysine, a potent inducible nitric oxide synthase inhibitor. Bovine monocyt
es produced nitric oxide in response to recombinant bovine interferon-gamma
alone or in combination with E. coli lipopolysaccharides. In these cells,
nitric oxide release was reduced by the addition of inducible nitric oxide
synthase inhibitors L-N-6-(1-iminoethyl) lysine and aminoguanidine. Lipopol
ysaccharides and recombinant bovine interferon-gamma increased nitric oxide
synthase mRNA in neutrophils, but nitric oxide release could not be detect
ed under any of the experimental conditions used. These results show that b
ovine epithelial cells and mononuclear phagocytes produce nitric oxide unde
r inflammatory conditions and suggest that these cell populations are respo
nsible for nitric oxide release observed during mastitis.