The Thymus Gland

I’ve been reading about the thymus gland. I thought this was a good review:

An Overview of the Thymus Gland, Lynne Eldridge MD, Very Well Health, 18 April 2022
Playing a role in immunity, autoimmunity, and aging

The thymus gland is a small organ in the upper chest … under the breast bone, above the heart, and sandwiched between two lung lobes. (it is distinct from the thyroid gland which sits several inches higher.)

The site above has a great interactive that you can use to view the gland from various perspectives. Here’s its basic location:

Note the location of the thyroid.

As we age, the thymus – a very important immune system organ – shrinks.

Your thymus gland reaches its maximum size when you’re a teenager. Then, it starts to shrink slowly. By the time you turn 75 years old, your thymus gland turns to fat.

The thymus makes lymphocytes or white blood cells. Actually, those cells are made in bone marrow and travel to the thymus to mature.

T-lymphocytes (T-cells) protect against infection and keep cancer cells at bay.

There are 3 main types:

  • Cytotoxic T-cells: These cells directly kill infected cells (include CD8+ T-cells)
  • Helper T-cells: These cells enlist B-lymphocytes (B-cells) to make antibodies. They also activate cytotoxic T-cells to kill infected cells. (include CD4+ T-cells)
  • Regulatory T-cells: These cells function as “police.” They suppress both B-cells and other T-cells if they are mistakenly harming the body.

As T-cells mature inside the thymus, they are taught to recognize foreign particles:

The part of the thymus called the cortex is where the T-cell boot camp training is held. Here, young T-cells learn to identify antigens or toxins linked to foreign cells and matter. This process is called “positive selection.”

Once the T-cells recognize specific pathogens, they travel to another part of the thymus gland called the medulla. Here, they get a different kind of training, “negative selection.” They’re introduced to the body’s antigens, so they don’t attack and harm them.

This prevents autoimmune disorders. These are medical conditions where things go wrong, and your cells attack your body tissues and cells instead of foreign invaders.

Not all T-cells make it through this selection process. Only about 2% eventually make it through both positive and negative selection.

Next, the survivors get exposed to hormones produced by the thymus gland to complete their training. Then they are released to do their job.

The body takes autoimmunity – self attacks – quite seriously. If T-cells start attacking our own tissues, we’re cooked. Multiple sclerosis, Type 1 diabetes, rheumatoid arthritis, are some of the autoimmune diseases that develop when the immune system goes awry.

The tapping issue …

Some people tap or thump their chest in the area of their thymus purportedly to “stimulate” it. I can’t find any good research that says tapping the thymus “strengthens or boosts” the immune system. (Vague terms!) Does it increase production of T-cells or something else that can be measured? Maybe it does, I just haven’t seen it.

I am inclined to believe that tapping this area, or any particular area, falls under the umbrella of energy therapy (e.g. acupressure or qi-gong tapping). Some of these therapies do have research to back them up (like this study on wrist acupressure and nausea.)

People are either quick to dismiss energy therapies as unscientific or quick to embrace them. In the middle are people like me who try to keep an open mind. I like to see well-run trials or controlled population studies but just because I don’t understand how something may work doesn’t mean it doesn’t work.

One more point … Saying that tapping near the thymus somehow affects the immune system seems like a way to legitimize energy therapy to a non-energy-therapy-believing Western world. It gives focus to an actual immune system organ.

Further reading:
Histology, T-Cell Lymphocyte, StatPearls, 8 May 2022
Is There Any Benefit To “Tapping” Therapy?, Dr. Weil, 14 October 2021

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