In a post a while back, I offered a brief overview of how it is that our immune cells get from the the blood to the site of inflammation: rolling, adhesion, activation, transmigration and chemotaxis. By far the best (if detailed) visual demonstration of this was the one I wrote about here.
But I've recently been sent two lovely clips focusing on the last step: chemotaxis. Basically, chemotaxis, in the context of our immune cells, refers to their ability to move towards a chemical substance. These are usually signals from either other immune cells or from foreign microorganisms. If you're really nasty and want to see your own neutrophils run around in circles, you can do what these researchers did: introduce a chemotactic substance by a constantly moving pipette, and watch the poor neutrophils go on a wild goose chase:
Of course, this is highly artificial, but it does show how amazingly, well, dextrous these tiny cells can be in pursuit of (what they think is) their prey. The following video clip, more than 50 years old now, shows a ferocious car chase between the local police and an intruder. Spoiler: the police get their man.