Foreign invaders, be they mold on the walls, toxins in the polluted air, food contaminants, viruses, bacteria, parasites or fungi, pose a threat to our health. Luckily, our body has a way of fighting these invaders. A complex network of organs, white blood cells, proteins, and signaling molecules collectively known as the immune system are ready to wage war on the enemy.
The first step is a mobilization of macrophages, a type of white blood cell whose name derives from the Greek for “large eaters.” In a process known as “phagocytosis,” macrophages swallow intruders and break them down with enzymes they release from special sacs called lysosomes. If the disease-causing organisms (pathogens) turn out to be overwhelming, macrophages send “danger signals” to immune “security troops,” especially two types of T cells. “T” cells originate. in the bone marrow, but derive its name from the thymus gland of the chest where they mature and learn to distinguish the “I” from the “not I”. This prevents “autoimmune reactions” in which the body attacks its own normal components as happens in lupus, rheumatoid arthritis, and multiple sclerosis, all examples of autoimmune diseases. When the “non-self” is to be attacked, the killer T cells release “cytotoxins” that destroy the cells, while the “helper T cells” coordinate the attack by sending chemical messages that attract other cells. immune and cause killer T cells to multiply.
While they are formidable workhorses, T cells can suffer from “T cell depletion”. Confrontation with cancer cells is notorious for causing this depletion. Fortunately, T cells can recover after each immune mission and take on a new challenge.
After the macrophages and T cells have chewed the invaders, the B cells arrive and sweep away the debris. In doing so, they identify specific components of the waste that were responsible for triggering immune activity (antigens) and learn how to produce special proteins called antibodies that will recognize the antigen if they find it again. This encounter will lead to the destruction of any organism that has the antigen. This is known as acquired immunity.
A question often arises about the possibility of “boosting” our immune system. Since food is the only raw material that enters our body, it is logical that all the functions of the body, including our immune system, are affected by what we eat. A diet of whole grains, vegetables, fruits and legumes with a minimum of alcohol, processed foods and refined carbohydrates helps greatly to improve overall health, including that of the immune system.
But wait. There is another way to increase our immune health. Speed up your lymphatic circulation! Lymph is the pale yellow liquid that drains from the blood to the surrounding tissues where it collects and then circulates through the body through the lymphatic vessels that closely resemble the blood vessels. This “lymphatic system” also stores “lymphocytes,” such as the T cells and B cells we’ve already found, along with “natural killer cells” that specifically attack cancer cells and cells. cells infected with a virus.
Finally, the lymph, along with the lymphocytes it contains, returns to the bloodstream through the lymph nodes, about 600 of which are found throughout the body. Thus, intruders fight both the lymphatic system and the bloodstream.
The lymph nodes store lymphocytes and also filter out cellular waste, viral waste, and damaged lymph cells. During an infection they have to work harder, so they swell. Immune cells also grow and multiply in the bone marrow, spleen, tonsils, and thymus gland, which are considered part of the lymphatic system.
The lymphatic system has no analogues in the heart, which is the “pump” that circulates the blood and therefore must depend on the activity of the surrounding muscles for circulation. This is where exercise comes into play! The more muscle movement, the faster the lymph circulates and the more continuously the lymphocytes are delivered to anywhere in the body where they may be needed, and the more efficiently cellular waste is managed. The old adage “rest, you oxidize” makes a lot of immune sense.
However, as people age, so does our immune system. The thymus, for example, experiences a “thymic involution,” that is, it shrinks over time. Regression begins at puberty and at age 75 or so, thymus is reduced to just adipose tissue.
The smaller the thymus, the lower its ability to prepare T cells. A reduced thymus means that our T cells decrease in number as we age and our immune response is less effective. We can’t slow down time, but we can slow down immune aging with exercise. No need to run marathons or buy luxury Peloton equipment. A simple walk after dinner or 30 minutes of pedaling with the old exercise bike works just as well.
In addition to boosting immune health, exercise also produces endorphins, the body’s natural painkillers along with dopamine and serotonin, the “hormones of happiness”. A win-win.
Dra. Nancy Liu-Sullivan has a PhD. in biology and served as a senior research scientist at the Memorial Sloan Kettering Cancer Center. She is currently a professor of biology at Staten Island College, City University of New York.