Xanthine oxidoreductase in human mammary epithelial cells: activation in response to inflammatory cytokines

Xanthine oxidoreductase (XOR) in human mammary epithelial cells was shown to have low true specific activity, similar to that in breast milk. Enzymic activity was increased in response to inflammatory cytokines; increases of 2–2.5-fold being seen with TNF-α and IL-1β and of approximately 8-fold with IFN-γ. No significant increase was seen with IL-6. A combination of IFN-γ and TNF-α, or of these two cytokines plus IL-1β, led to responses...