'Our Immune System'

SUBSTACK ARTICLE #56

‘Our Immune System’

Substack Article #56

Before retiring I was a family doctor, a generalist. That means I knew a little bit about many things but I didn’t know a lot about any one of them. As a frontline generalist I have diagnosed and treated many patients with infectious diseases, and I provided vaccines as well. Despite that, I would in no way consider myself an expert with respect to the immune system. So, this article is a shallow overview of the immune system from the perspective of a non-expert. Nevertheless, I hope that it will be useful.

It is easy to think that the immune system is like our military—it is only called into serious action when a conflict breaks out. But the truth is, the immune system is battling potential invaders constantly. Our skin is covered in germs, our gastrointestinal tract contains more bacteria than we have cells in our body, and our brain is being continuously protected from microbes entering its space by what is referred to as the ‘blood brain barrier’ (BBB). And those are just the germs with whom we live in a more or less symbiotic relationship. There are also all of those other foreign and potentially more pathologic organisms we must be on the lookout for at all times. In addition, on a constant basis lots of our own cells become dysfunctional because of normal aging and decay, which to some degree is accelerated by environmental factors like radiation and toxins. Those cells, too, must be dealt with by our immune system before they become a threat to us, by becoming cancerous, for example.

So, our immune system doesn’t suddenly jump into action only when we get a ‘cold’; it’s always at work. We get exposed to germs all the time, and if the amount we get exposed to (referred to as ‘load’) is small, and our immune system is healthy, we are much less likely to get sick. In fact, a small enough ‘load’ might be what we need to recognize the organism sufficiently well to develop antibodies without getting terribly sick at all. By doing so, the next time we see it, our immune defenses are primed and waiting, like an army with their weapons locked and loaded. We are not nearly as helpless against infectious diseases as is sometimes portrayed.

Vaccines try to take advantage of this reality—expose the body to a very small amount of inactivated virus, for example, and the patient will not get sick but develop antibodies that will be protective when the intact virus is next encountered. But we must remember that a frail and elderly person in a nursing home may succumb to a very small loading dose of an organism. And no matter how effective the vaccine against such an organism, their immune system may also be so frail that it can’t mount a sufficiently potent protective response. Sometimes even a good immune response may not be enough if a patient has such a compromised respiratory system, for example, that they still can’t fend off a microbe that infects their lungs.

One way to keep our immune system healthy is to keep our entire body healthy—a good diet, regular exercise, sunshine and fresh air, etc. Given the powerful mind-body connection, looking after our mental health helps a lot, too. The converse is also true—an unhealthy body or mind will adversely affect our immunity. Lots of factors, many I suspect we do not as yet fully understand, can help or hinder. So, it is a multi-pronged approach; like the rest of our body, there is no one magical potion or activity that can keep the immune system strong. By analogy, there is no one intervention that will make an old clunker of a car work like new again—there may be many parts to be replaced for it to run well. There aren’t always easy fixes.

There are three major elements of our immune system: innate and the two adaptive ones, humoral and cell-mediated. The innate is the one with which we are all born and is a general defense mechanism; it is probably the one most affected by poor lifestyle and habits. Our skin and mucous membranes (the covering tissues inside of our bodies are mucous membranes, as opposed to the covering tissue on the outside we call skin) are part of our first line of defence and that is where good self-care plays a big role.

But you can have too much of a good thing—bigger is not always better. You may have heard of ‘cytokine storm’, for example. As well, we don’t always know why, but sometimes our immune system goes overboard and attacks us—autoimmune disease—so we must recognize that like much of life it too is a delicate balance. The control of autoimmune disease often requires drugs that suppress the immune system quite broadly, although research has led to more focused ones which have less effect on the immune system as a whole.

And like everything else, there is still a lot we do not know. Dengvaxia, the vaccine against Dengue Virus developed several years ago, surprised researchers when they discovered a new phenomenon referred to as Antibody Dependent Enhancement (among other names). Sadly, children who had had Dengue who then took the vaccine and were later infected with a different strain died unexpectedly. The universe is a complicated and complex place.

And it doesn’t help that many organisms mutate; bacteria develop resistance to antibiotics, for example. Unfortunately, Coronaviruses mutate frequently which has always been part of the problem with developing effective vaccines against them. Before COVID, this virus family so commonly caused disease that lots of time, effort and money had already been poured into research for vaccines but without success.

Prior to the pandemic many of us probably took our immune system for granted more than we do now. Do you feel that the authorities provided enough education about our immune system and how to strengthen it during the pandemic? Or did you have to do most of the research on your own? Have you ever wondered if some of the things they suggested or required we do may have weakened our immune systems? One thing is likely true: many of us will appreciate our immune system more than ever.

J. Barry Engelhardt MD (retired) MHSc (bioethics)

CAERS Health Intake Facilitator