Microbial Chess

Queen of the Bean contends that a continuous chess game is going on inside of us every day:

The human body is constantly being bombarded by pathogens day in and day out and as such has evolved a number of defences to help protect it....The body's first line of defence is a physical one ... mainly consists of skin ... and mucous.... The body's second line of defence is the non-specific phagocytic cells (white blood cells).... The third line of defence is the specific humoral response and cell mediated response.

If you link the second and third lines of defence it's sort of like a game of chess. The second line of defence are the pawns, they just go where you tell them to and haven't got much of a range of things they can do. The third line of defence is like [the] back row that has all the other fancy pieces in it. When they're called out to battle you know the fate of the fight will be decided because they're the last hope. Like with the rules of chess, there are only certain things that they are allowed to do, but they each do their thing and sometimes pull out surprising little tactics...