Immune cells called T cells battle infections and guard against cancer. But first they need to be tipped off about the threat. The informants are a group of cells called dendritic cells, which chew up infected and damaged cells and present the regurgitated pieces to T cells. If the T cells judge the pieces to be foreign or in need of removal, they reproduce, forming an army of clones that hunt down infected and rogue cells in the body.
--Dan Ferber, ScienceNOW Daily News

But here's the best news if you happen to be somewhere in the country right now that's getting a little sun. That which calls the T cells into army action is none other than a sunbeam producing a little vitamin D. Once the T cells are all over D'd, "the altered T cells make a beeline for the outer layer of the skin, where they began destroying defective and infected cells."

So yesterday p.m. I got outside in short sleeves and destroyed some defective cells with sunshine. I also chopped up a bit of ice on our front sidewalk and succeeded in turning our bumpy, navigable path into a skating rink.