If any microbes successfully weave their way through the mucus, run the gauntlet of phages and AMPs, and sneak through the epithelium, there’s a battalion of immune cells on the other side to swallow and destroy them. These cells aren’t just sitting around, waiting for the worst to happen. They are surprisingly proactive. Some reach through the epithelium to check for microbes on the other side, as if feeling around through the slats of a fence. If they find bacteria in the demilitarised zone, they capture them and bring them back across. By taking these prisoners, the immune system gets
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third layer, immune cells, anti-bodies
