Immune: A Journey Into the Mysterious System That Keeps You Alive

by Philipp Dettmer

Maybe one of the most important differences to our evolutionary past may be that modern diets contain vastly less fiber than they used to. Fiber is an important power food for a lot of useful and friendly commensal bacteria, and the fact that we just eat less and less of it means that we can’t...

The transition of our microbial microenvironment and stunted microbiomes was probably a gradual one that happened only in the last century or so. As every generation moved a bit farther away from the natural environment their microbiomes became less diverse and their children inherited their microbiome. Over time the average diversity of the microbiome in developed countries seems to have fallen considerably, especially compared to humans still living a more traditional and rural lifestyle.

Boosting the Immune System is a horrible idea that is used by people trying to make you buy useless stuff! Luckily the danger is pretty mild that you could actually boost your immune system since basically nothing you can buy legally actually does it! Even the mere term “strong immune system” is a misnomer. Over everything else, you want a balanced immune system. Homeostasis. Aggression and calmness. You want elegant dancers who remember the choreography really well over pumped-up rugby players who want to smash stuff. In all likelihood, your immune system works exactly as intended.

At least for now, there are no scientifically proven ways to directly boost your immune system with any products that are easily available. And if there were, it would be very dangerous to use them without medical supervision.

The most important thing you need to do to have a healthy immune system is to eat a diet that provides you with all the vitamins and nutrients your body needs. The reason is, simply, your immune system constantly makes many billions of new cells. And all these newborn cells need resources to function properly. Malnutrition is strongly associated with a weak immune system. If you are starving, you are more susceptible to infections and diseases because your body has to make hard decisions and the immune system suffers from that. But if you eat at least somewhat of a balanced diet with some fruits and vegetables, you will get all the micro and macronutrients for your immune system to work just fine. Interestingly, even in developed countries there is micronutrient malnutrition, especially among elderly people. Which just means that someone has a deficiency of essential nutrients and vitamins—usually because they don’t eat enough or have too little variety in their diets. So only eating pizza is not healthy but this should already have been clear. In all likelihood if you eat sort of OK, your immune system works just as it should.

On top of just eating right, the positive health effects of even moderate regular exercise have been known for a long time. Your body is made for movement and so moving it around a bit keeps a variety of systems in good health, especially your cardiovascular system. Working out also directly boosts your immune system, because it promotes good circulations of fluids throughout your body. In a nutshell, just by moving, stretching, and squashing your various body parts, your fluids flow better and more freely than if you lie on your couch all day. And good circulation is go...

OK, so boosting and strengthening the immune system is complicated for experts, and outside of a healthy lifestyle is pretty impossible (and ill-advised) for regular people. But there is actually a huge thing you could do to at least prevent damage. It turns out that many people are actually suppressing their immune system without being aware of it.

The thing about stress is that it is similar to your immune response in one extremely important aspect: When it works as it is intended to, stress is a great mechanism that helps solve an immediate problem and then shuts itself off afterwards. But the nature of the stressors we encounter in the modern world is different than the ones we evolved with. In the past the lion either got you or you escaped—either way, your stress stopped. It rarely followed you around for weeks or months, like exam season or a large project for a demanding client. And so a mechanism that was meant to support short bursts of activity has turned into a chronic background noise.

Stress also releases hormones like cortisol that shut down and suppress your immune system, making it weaker and less able to do its job properly in a variety of ways. Wounds heal slower, infections are more likely to break out and to cause disease. Already present pathogens or diseases can no longer be held in check efficiently, leading to an outbreak of herpes, for example. Or in more serious cases, to a much faster progression of HIV. Chronic stress means a chronic release of cortisol, which generally slows your defense systems down.

When cancer cells form in solid tissue, like your lungs, muscles, brain, bones, or sexual organs, they form tumors. You can imagine tumors basically like cells starting a new small village that eventually grows into a metropolitan area sprawling across the continent that is your body.

In contrast to tumor-forming solid cancers, “liquid” cancers affect your blood, bone marrow, lymph, and lymphatic system and often start in your bone marrow, and what basically happens here is that the superhighways of your vascular and lymphatic systems are overwhelmed and crowded out by useless cancer cells. (Liquid cancers still are made from cells, they are not actually liquid.) Leukemia, or blood cancer, is often used as a sort of catchall name for these kinds of cancers.

Despite the horrible harm they cause, cancer cells are not evil. They don’t want to hurt you. They don’t want anything, really. As we established, cells are protein robots that just follow their programming, which unfortunately can be broken and corrupted.

In your cells most of this damage just happens through the basic process of living life, through your cells dividing and keeping the body going, without any special reason or cause. It is just statistics and bad luck. You can do a lot to increase your chances of getting cancer through your lifestyle by doing things that damage your genetic code, like smoking cigarettes, drinking alcohol, or being obese, through contact with carcinogenic substances like asbestos, or simply by enjoying beautiful summer days without sunscreen.

All in all, the easiest way to get cancer is to be alive long enough. It is statistically impossible to not develop some cancer at some point in your life, even if it ends up not being the cause of your death.

If cells lose the ability to kill themselves when it is time, when they become unable to fix the mistakes that are naturally amassing in their genetic code, and when they begin to grow without restraint, they become cancerous and dangerous.

Cancer cells walk this process back and stop being part of the collective and in some sense, become individuals again. And that would be OK in principle. Your body can handle a few cells doing their own thing and even live in harmony with them. But unfortunately cancer cells usually do not content themselves with doing their own thing, but divide and divide, again, and again. They turn from being an individual to a collective again. A sort of new organism within you. Still part of you but also not you at all. They take the resources you need to survive, destroying the organ systems they used to be a part of, and begin competing for the space that you inhabit.

So congratulations, you have a proper cancer cell. It is no longer able to monitor and repair its genetic code, it can’t kill itself anymore, and it has lost its restraint and is beginning to multiply rapidly. And it mutates more with each generation. Not great, not terrible.

For example, one of the genius and horrifying methods cancer cells have to protect themselves from the immune system is targeting inhibitor receptors on Killer T Cells and on Natural Killer Cells. Inhibitor receptors inhibit these cells from, well, killing. They are a sort of off switch that deactivates Killer Cells before they can attack a cell and destroy it—which in principle is a good idea. We’ve hit on the fact of how dangerous your immune system is many times, and there need to be mechanisms to stop overeager immune cells, so inhibitor receptors play an important role in the complex concert of your immune system. But unfortunately cancer cells can mutate in a way where they are able to shut down your Killer Cells. So now we have a cancer cell that is able to shut down the defenses of the immune system. And so a new tumor begins growing, producing thousands of new clones that are changing and mutating again.

If all of these things come together the cancer has basically won and tamed the immune system successfully. All avenues of attack have been shut down and uncontrollable growth is the consequence. In the end, if left untreated, these new and optimized cancer cells become metastatic, which means that they want to explore the world and expand into other tissues or organs, where they continue growing. If this affects vital organs like the lungs, the brain, or the liver, the intricate and complex machine that is your body begins breaking down.

Imagine installing new but useless parts into your car engine every day—your car will work for a while but at some point the engine will no longer start. This is how cancer kills you in the end. By taking up so much space and stealing so many nutrients that your true self has no room to properly function anymore and your affected organs have to shut down.

Cigarette smoke is saturated with over 4,000 different chemicals, many of them with unknown properties and interactions with each other. But we know for sure that nicotine, the magic and vile substance that makes smoking addictive, suppresses your immune system. It makes your immune cells slow and ineffective.

All of this beautiful complexity carries a hint of sadness. It stings a bit to know that life is too short and too busy to truly learn about all the layers that make up reality. But hey, in the end there is nothing we can do about that. What we can do is to take up the challenge from time to time and put in the effort to get a glimpse into something so much larger than us. Even if we will never get to the bottom of it.