Sometimes scientists are so busy selling us a bill of goods that they seem to lose track of their train of thought.
Consider this from one of the foremost antioxidant researchers, Lester Packer (The Antioxidant Miracle, 2000. Chapter 9: The Flavonoids, p. 228):
“In cell culture studies, we used bacterial toxins to trigger the release of nitric oxide from macrophages. As expected, large amounts of the nitric oxide radicals started killing off the macrophages themselves!…However, when we added Pycnogenol to the mix, nitric oxide production decreased significantly, and macrophages were unharmed…”
Sure, the macrophages were unharmed. You succeeded in quenching their ability to kill anything – bacteria and themselves. A compound strong enough to quench the nitric oxide the immune system is using to kill invaders is probably not a good staple in the antioxidant defense system. Nature uses a weaker antioxidant to protect macrophages: a high (100-1000x serum levels) concentration of vitamin C. Protects macrophages without inhibiting their ability to kill invaders.