Anyway, Karsak and the rest of the research team decided to take things a step further, and see if cannabinoids from Cannabis itself could reduce skin sensitivity in normal mice. So they cooked up some kind of marijuana salve and applied it to mice that had been exposed to a synthetic allergen (2,4-dinitrofluorobenzene). The results: a 50% reduction in inflammation and swelling. While the mechanism of action is still unclear, preliminary evidence seems to point to cannabinoids' role in modulating the expression of genes that code for pro-inflammatory compounds like histamine. I'd be curious to hear more about this: it could help explain how effective marijuana has been in curbing GI and upper respiratory inflammation (colitis, asthma, e.g.) in previous studies, some of which were in humans.
One final note of wisdom from Roman Rukwied, a pain and inflammation researcher: "We are far before the day when we could say 'oh, I have a nickel allergy. I will smoke marijuana and I won't have it anymore'," he says. "That is definitely not the case." Fair enough.