Covid-19 and the Immune System: This Doctor Makes House Calls
At the first hint of invading organisms, the immune system launches an orchestrated attack that usually destroys and eliminates them
Our immune system will memorize the pathogen after an infection and after reinfection recognize and destroy the same pathogen.
Three different cells in the immune system retain memory: Memory B cells, memory T cells, and follicular memory T cells.
Like the neurons, immune cells store and share information, memory with each other and the rest of the embodied mind.
Our bodies are patrolled 24/7 by a silent army of vigilant police officers, health inspectors, doctors, and ambulances. They protect us from uninvited guests including bacteria, viruses, fungi, as well as intrusive substances such as a splinter or an ingrown toenail. Basically, anything that does not belong in our bodies attracts their attention. They repair injuries and dispose of waste. And they keep records of the miscreants they encounter for future reference. All this and more is what our immune system does for us to keep us healthy.
How It Works
The immune system has evolved to recognize and respond to threats to health, and to provide life-long memory designed to prevent recurrent disease. The immune system is made up of a large variety of white blood cells, some of which circulate through our arteries and veins, while others reside in various tissues of the body, including the lymph nodes and the skin.
The immune system protects the body by producing antibodies, which are proteins that help to prevent intruders, called antigens, from causing much harm. After an infection with a pathogen, a cascade of reactions will usually sets into motion. Among others, the immune system will start to produce the specific type of antibody designed to protect against that particular pathogen. The body is capable of creating literally billions of antibodies that are adept at fighting off billions of potential invaders. And our immune cells are very clever. They can learn on the job, remember what they have learned, and apply this education in response to future challenges.
Among the key players in the immune system are two types of white blood cells known as T cells and B cells. B cells make antibodies specific to particular pathogens. T cells change their own shape to surround, engulf, and thus destroy the invader. Then, after the disease is eliminated some T cells and B cells are converted into memory T and memory B cells.
Vaccination (immunization) is based on this premise. When a person is immunized (for polio, chickenpox, COVID, and others) they are given a small dose of the appropriate antigen, such as dead or weakened live bacteria or virus, to activate immune system “memory,” which then allows the body to react quickly and efficiently to future exposures. This is also why, generally speaking, once you’ve had chickenpox or measles, or some other childhood illness, you don’t get it again—the antibodies that were activated the first time, are still there in your immune system.
An interesting corollary to this kind of learned immunity is something called the Hoskins Effect, which refers to the fact that the immune system responds most powerfully when it re-encounters the exact same infection to which it was previously exposed, and less powerfully to a slightly different strain or version of it. This explains why having been vaccinated against one variant of the COVID virus is less effective against a new variant. Researchers at the University of Birmingham demonstrated that a single cycle of activation of naïve T cells leads to long-term epigenetic changes in these cells forming the basis of a long-term memory that allows for an immediate response when the body encounters an infection and T cells are activated for a second time.
In addition to the memory cells that are on patrol in the circulation, Australian scientists have discovered that the immune system also leaves behind a garrison of memory cells, follicular memory T cells, strategically positioned at the entrance of the lymph nodes, particularly those that are potential sites of microbe re-invasion, like in the neck, under the armpits and in the groin area, to screen for return of antigens they have encountered before. This is an important finding because, until now, people have thought that memory is provided by only circulating cells.
Professor Jochen Hühn at the Helmholtz Centre for Infection Research in Germany has pointed out that lymph nodes are basically the immune system’s meeting points. His team also found that the location of the lymph nodes was directing the development of the immune cells they contained. They did so by collecting lymph nodes from various parts of rats’ bodies and transplanting them to different locations. It seems that the transplanted cells retained their original capacities for weeks. Since all the cells within the lymph node, including immune cells, are constantly regenerated, the researchers further concluded that this memory was being encoded and passed on from one generation to the next.
Response to Stress
What role does the immune system play in how we respond to stress? We know that stress increases the production of cortisone by way of the HPA axis. Increased cortisone levels inhibit the immune system. That is why when people are under stress or feel anxious or depressed, they are more likely to suffer a cold or the flu or have higher rates of infections. On the other hand, when the adrenal glands become depleted and can no longer produce adequate amounts of cortisone, the immune system goes into overdrive and may turn against its own body. Ideally, what you want is a Goldilocks condition, not too much and not too little cortisone—just the right amount. Biologists refer to a system that is in equilibrium as being in a state of homeostasis.
The Good News
How do we counteract the effects of stress to our existence at the molecular level?
What are the concrete things we can do to actively promote more favorable gene expression particularly, in the immune system? One answer is through mind-body practices, like meditation, that according to Steven Cole, Professor of Medicine, Psychiatry and Biobehavioral Sciences UCLA School of Medicine, has been shown to cultivate positive and happy immune cells. Research has linked meditation to higher antibody production, reduced negative inflammatory activity, increased positive antiviral response and improved function of specific strains of immune cells.
References
Bevington, S. L., Cauchy, P., . . . & Cockerill, P. N. et al., (2016). Inducible chromatin priming is associated with the establishment of immunological memory in T cells. The EMBO journal, 35(5), 515-535.
Dörner T, Radbruch A. (2007). Antibodies and B cell memory in viral immunity. Immunity. 27(3): 384-92.
Moran, I., Nguyen, A., & Munier, C. M. L. et al., (2018). Memory B cells are reactivated in subcapsular proliferative foci of lymph nodes. Nature communications, 9(1), 1-14.
Cording, S; Hühn, J; Pabst, O et al., (2013). The intestinal micro-environment imprints stromal cells to promote efficient Treg induction in gut-draining lymph nodes. Mucosal Immunology 7(2), 359-368.
Davidson, R. J., Kabat-Zinn, J., Sheridan, J. F. et al., (2003). Alterations in brain and immune function produced by mindfulness meditation. Psychosomatic medicine, 65(4), 564-570.
About the Author
Thomas R. Verny, M.D., the author of eight books, including The Embodied Mind, has taught at Harvard University, University of Toronto, York University, and St. Mary’s University of Minnesota.
