The Real Immune System

The integument is generally underappreciated as the true barrier against infection.

When physicians and medical researchers refer to the immune system, they usually mean the extremely complex system of white blood cells and antibodies that attack and destroy microbial invaders that get into the body’s tissues.  Yet this activation only occurs after there has been a breach, making that system more of a border patrol than one which confers true immunity.

The paradigm shift in medicine is to consider the integument as the true immune system.  The human is wrapped by a continuous sheet of integument: the epithelial lining known as skin is continuous with the epithelium lining the inner lumen of the intestinal tract, the two epithelia joining each other at the mouth and the anus.  These epithelial layers consist of continuous sheets of cells bound to each other by what are term tight junctions, and they sit on a solid basement membrane.

The body is roughly 60% water, which means that we are mostly water.  Yet, we don’t leak.  The reason we don’t leak is that our bodies are wrapped by this continuous sheet of integument.  If water can’t get out, then bacteria cannot get in, because molecules of water are infinitely smaller than bacteria, which themselves are made up of water.  (The sweat and other fluids that flow off the intestine do not represent leaks; they are actively secreted by the lining cells.)

Where we really live is in the interstitium, which houses the cells (nerve, bone, and muscle) responsible for our movement through the environment.  The so-called immune system (i.e., border patrol) also lives in the interstitium seeking defects and invasion.  Unless the integument is violated, there is no work for them to do.

If the integument is intact, we are truly immune.  It takes a breach of the integument, even microscopic, to enable microbes to infect us, thereby activating the so-called immune system.