How Your Immune System Functions
Doctors and researchers often describe the immune system in military terms. They’ll call it our “first line of defense” against “invaders.” Some describe it as the body’s “defense department,” which “captures and destroys.”
It’s not a bad metaphor. Your immune system is a complex network of cells located throughout your body. It knows how to recognize and attack harmful bacteria, germs, microbes and parasites. These harmful “invaders” enter your body in one of four ways—through the skin (if there’s a cut, for example), through the respiratory system (nose or lungs), through sexual contact and through the gastrointestinal tract, or gut.
The gut is possibly the biggest challenge to the immune system. The surface area of the gastrointestinal tract is about the size of a tennis court. There’s plenty of opportunity for germs to cross the lining of your intestine and enter your bloodstream, causing the immune system to respond immediately.
White blood cells—crucial to immune system functioning
White blood cells are important components of the immune system. Some white cells send out signals to block an infected area, so that the infection isn’t able to spread to other areas of the body. Other white cells chew up the infectious agent and send out messages that cause the creation of even more immune cells to help in the fight.
We all have our own, unique molecular code that appears on the surface of the cells of our body. Certain white cells of the immune system—T cells, they’re called—learn how to recognize this code. When the T cells come in contact with a cell whose code they don’t recognize, they attack and eliminate it, and then create new T cells that are programmed to remember to fight off that particular “invader.” The new cells are called helper T cells, and they can help the immune system react even faster the next time the invader appears.
The immune system is constantly working in this way, identifying, destroying and preparing for the next attack. The white cells circulate through the body’s lymphatic system, which is connected to every organ in the body except the brain. The cells go into “battle mode” when an infection takes hold, causing lymph nodes to swell.
When the balance is lost
Some T cells take target bacteria, viruses and parasites. These are called TH1 cells. Other T cells, called TH2 cells, focus on allergic reactions and responses to already-recognized invaders. If your diet is not healthy, if you’re under stress or if you’re exposed to toxins in the environment, your TH1 cell activity may not be up to the level it should be. When the TH1 activity is weakened, TH2 activity can become overactive. The TH2 cells secrete a substance that can cause inflammation and fever.
If this imbalance continues unchecked, the immune system becomes less effective, and autoimmune disease, such as rheumatoid arthritis, lupus, multiple sclerosis, and many other conditions can be the result.
Be sure to read this month’s other two topic-of-the-month articles about the immune system, describing what’s going on in your body when you have an autoimmune disease and what you can do to give yourself the best chances of keeping your
Baron-Faust, J. Buyon. The Autoimmune Connection. Contemporary Books, 2003; M. Hyman, M. Liponis. Ultra-Prevention, The 6-Week Plan That Will Make You Healthy for Life. Scribner, New York, 2003. R. Klatz, R. Goldman. Infection Protection. HarperCollins Publishers, New York, 2002.