It’s enormously complicated and also unique to you. Immune cells are generated from lymph nodes, bone marrow, the spleen, the thymus and more. You have, at the least, three hundred different types of immune cells at work (e.g., lymphocytes, T-cells, antibodies). The system must respond to toxins, drugs, cancers, foreign objects, and even your state of mind (if stressed, you are much more likely to suffer an infection). No wonder the system sometimes makes mistakes and attacks innocent cells, giving us autoimmune diseases such as multiple sclerosis, lupus, rheumatoid arthritis, and Crohn’s disease.
We have two kinds of immunity: Innate immunity, which
kicks off the immune response, stimulating our bodies to combat invaders and build
defenses; Adaptive immunity, which creates pathogen-specific antibodies
and memory T-cells, making it possible for our bodies to quickly respond if the
same invader strikes again.
As we age our immune systems stiffen up, becoming slower to
turn on and off. For one thing, the system becomes chronically active as though
our bodies were constantly responding to attack. As the years go by, our level
of inflammation rises. It’s partly the result of cellular senescence, in which cells
stop replicating and trigger an immune response. What’s more, our thymus glands
atrophy, which reduces their production of killer T-cells that fight infection (T
for thymus). To make matters worse, around twenty percent of our T-cell repertoire
is devoted to fighting a single virus: human cytomegalovirus (HCMV), a strain
of herpes that usually has no symptoms and does nothing but consume T-cell resources.
Great. Maybe that's why some days everything seems to hurt.
By the way, even though I'm mostly anti-medical intervention, I plan to get the coronavirus vaccination. I'm not irrational.
For an introduction to this blog, see I Just Say No; for a list of blog topics, click the Topics tab.
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