Inside our body there is an amazing protection mechanism called the immune system. It is designed to defend us against the millions of bacteria, microbes, viruses, toxins and parasites that would love to invade our body. To understand the power of the immune system, all that we have to do is look at what happens to anything once it dies. That sounds vulgar, but it does show you something very important about the immune system. When something dies its immune system (along with everything else) shuts down.
Within hours, all sorts of bacteria, microbes, and parasites invade the body. None of these things are able to get in when our immune system is working, but the moment the system collapses the invasion begins. It takes these organisms only a few weeks to completely dismantle a dead body and carry it away, until all that’s left is a skeleton. Obviously our immune system is doing something amazing to keep all of that dismantling from happening when we are alive!
More than a 100 years ago, scientists did a simple experiment. They used a group of volunteers who were allergic to a flower. During a series of tests, it was demonstrated that an artificial flower triggered the allergic reaction just like the real one did. It seemed that the brain could influence the working of the immune system. In a more recent study conducted on professional actors1 they were required to do either a tragic scene or a happy one.
The ones doing the tragic scene showed a stress response with decreased immune function. In contrast, the actors who were doing an euphoric scene showed an improvement in their immune response. It seems clear that the brain can poke its proverbial nose into the affairs of the immune system. How does the brain go about meddling in the immune system? The autonomic nervous system sends nerves into the tissues that form or store the cells of the immune system that end up in the blood circulation.
Further, the tissues of the immune system are sensitive to all the hormones released by the pituitary.2 Studies such as these clearly show the strong link between the nervous system and the immune system. The obvious conclusion is that stress can alter the immune functions. To appreciate the role of stressors in disrupting the immune system, we need to take a look (as is the case in this book, it will be a brief look) at the functioning of the immune system and then analyse the functioning during stress.