Like an antenna, antibodies pick up signals. But each antibody is finely tuned. It picks up only one type of signal. In fact, so particular is each antibody that most of the billions of white cells coursing through us generally have unique antibodies on their surfaces. So unlike most antennae—say, radio towers—the antibody receptor doesn’t pick up just any signal. It picks up one. It is evolved to connect to a single kind of organism.
