YOUR THYMUS GLAND

I WILL PROTECT YOU EVEN AFTER I’M LONG GONE. – THYMUS GLAND

WHAT IS IT? WHERE IS IT LOCATED? WHAT IS ITS ROLE IN THE BODY?

Your thymus gland is a specialised organ of the immune system. It’s also part of the endocrine system because it produces and releases hormones. The thymus gland is named as such because it resembles a bunch of thyme leaves.

Your thymus gland is located behind your breastbone (sternum) and between your lungs. It has a pinkish-grey colour and has two lobes. It doesn’t function throughout your entire life, but it plays a huge role when it’s active.

The thymus gland started performing its role way before you were born. Unlike most organs in your body, the thymus is different because it is at its biggest and heaviest when you are a child until puberty (up to 50 grams). After puberty, your thymus slowly loses its mass, shrinks, and is primarily replaced by fat. Under normal conditions, you’ll be

surprised to know that in your 70s, the thymus is reduced to a small lump of fatty or adipose tissue (less than 5 grams). But your thymus gland promised that it would protect you even after it’s long gone. So that’s precisely what it does. By the time you reach those wonderful teen years, your thymus has produced all your needed T-cells.

THE FUNCTION OF THE THYMUS GLAND LARGELY DEPENDS ON THE CELLS FOUND IN IT. THERE ARE THREE PREDOMINANT GROUPS OF CELLS FOUND IN THE THYMUS: T-CELLS, THYMIC EPITHELIAL CELLS, AND B-CELLS.

1. As part of the immune system. The T-cells (also called T-lymphocytes and thymocytes) start first as stem cells in your bone marrow. Stem cells are your body’s raw material from which all the other specialised cells come from. They arrive at the thymus gland via the bloodstream. The stem cells then mature into T-cells that can attack foreign bodies (like viruses) but not your own cells and tissues. The primary function of your thymus is to produce mature and battle-ready T-cells. The T-cells are ready to deal with pathogens (viruses, bacteria), allergens, and cancer cells. T-cells also help your body protect itself against autoimmunity. Autoimmunity happens when your immune system attacks itself.


2. As part of the endocrine system. Thymic epithelial cells, or TECs for short, produce hormones (thymopoietin, thymosin, thymulin) needed in the development of T-cells. The time will come when these mature T-cells will leave your thymus gland and go to other parts of your immune system. Further maturation develops through the action of hormones released by thymus cells. Some evidence suggests that thymosin and other hormones slow down the ageing process. (2)


3. B-cells (also called B-lymphocytes or thymic B cells) are present in small numbers in the thymus gland. The latest research on this type of cell indicates that they’re different from other B-cells found in other lymphatic issues. There’s also evidence that they have originated deep within the thymus. Their main function is not fully understood, and more research is being done to address this. For now, it’s accepted that they help determine harmful cells that have interacted with foreign antigens. Besides these three groups of cells, there are other cells found in the thymus, like macrophages and dendritic cells.

YOUR THYMUS GETS SICK TOO

Like any other gland or organ in your body, the thymus has its fair share of diseases that affect its function throughout its lifespan. Below are some examples:

1. A baby may be born without a thymus or a hypoplastic (arrested in development) thymus. This condition may be a part of a syndrome called DiGeorge syndrome. Other characteristics of the syndrome are best remembered with the phrase CATCH-22 (see below). The number 22 stands for chromosome number 22. A part of it is missing if you have DiGeorge syndrome. Infants with DiGeorge syndrome have frequent infections, delayed growth and development, and poor muscle tone.
1. C – cardiac defects or problems
2. A – abnormal facies (abnormal facial features)
3. T – thymic hypoplasia or absent thymus gland
4. C – cleft palate
5. H - hypoparathyroidism


2. A hyperactive thymus gland causes it to increase in size and may be secondary to the following conditions:



Myasthenia gravis is a chronic and debilitating autoimmune disorder wherein antibodies mess up the communication between muscle and nerves. This results in the weakness of skeletal muscles. It particularly affects the skeletal muscles of your body that move the throat, eyes, mouth, and limbs. It usually affects young women (between 20 to 30 years old). The exact cause of this disease is still unknown. People with myasthenia gravis have large thymus glands that produce antibodies that aggravate the miscommunication between muscles and nerves. Up to 50% of people with myasthenia gravis may have a thymic tumour.




Malignant tumours (cancer) of the thymus. Two types of malignant tumours primarily come from the thymus itself: thymic carcinoma and thymoma. Thymic carcinoma is a fast-growing cancer that’s difficult to treat. The symptoms of this type of cancer include a hoarse voice, chest pain, cough, shortness of breath, and swelling in the face, neck, or upper body. In addition, it can metastasise (spread to other organs) to your bones and lungs.




The other type of cancer, thymoma, grows slowly and is usually confined within the thymus. This tumour may be slow-growing, but it can lead to a condition called pure red cell aplasia, characterised by severe anaemia. This means you don’t have enough red blood cells in your body to sustain normal functions. Red blood cells carry oxygen to your cells and remove carbon dioxide.




NETTS, which stands for neuroendocrine tumours of the thymus, is a specialised type of thymic carcinoma. They’re quite rare and aggressive. They’re more common among males in their 40s and 50s. Approximately 8% of people diagnosed with NETTS have a second cancer somewhere in the body happening at the same time.




Cancers that affect the lymphatic system . Some types of blood cancer, called non-Hodgkin’s lymphoma and Hodgkin’s lymphoma, can affect your thymus.




Hyperthyroidism. Some people with hyperthyroidism also experience an increase in the size of their thymus. This is due to excessive levels of thyroid hormones. It’s a benign condition that commonly improves after treatment of hyperthyroidism.

WHAT DOES THYMECTOMY MEAN?

Thymectomy is the removal of the thymus gland through surgery. It’s commonly indicated as a treatment for thymoma and myasthenia gravis. Less common indications include neuroendocrine tumours, thymic cysts (and other benign tumours), and thymic carcinoma. If a normal functioning thymus is removed from a newborn, the T-cell population drastically decreases in the blood and lymphatic system. As a result, the immune system fails, and the infant experiences a gradual wasting disease. The child also has an increased risk for asthma, thyroid disease, infections, autoimmune disorders, and even cancers. Remember, T-cells also help in preventing cancer.

HOW TO HELP YOUR AGEING THYMUS GLAND – BOOST YOUR IMMUNE SYSTEM

By the time you have reached puberty (we’re assuming you’re an adult now), your healthy thymus gland has produced all of the T-cells you will need. At this time, the best way to support your thymus gland is to strengthen your immune system. When your thymus gland starts to decline in function because of getting older, your other lymphoid tissues take over and ensure that you maintain a healthy and fully functioning immune system. Boost your immune system if you really want to help your thymus gland. For now, the best way to boost your immune system is to adopt a healthy lifestyle. These include the following:

1. Eat a well-balanced diet. If you can’t maintain one, try taking good quality supplements.
2. Don’t smoke or stop smoking. Drink alcohol in moderation.
3. Keep your weight within the healthy range and exercise regularly.
4. Get enough sleep.
5. Reduce stress.
6. Take preventive measures to prevent infection, such as cooking meat properly and washing your hands frequently.

The thymus gland is an integral part of your immune and endocrine system. Your immune system can’t function optimally without it. It trains your immune system to protect itself against infections and possibly cancer way before you are born. It reaches its peak performance during your teen years. There’s still a lot to learn from the thymus. It’s only now that researchers and scientists are examining it closely, especially its enigmatic roles in the ageing process and autoimmune disorders. We’ll be hearing more from this previously forgotten organ.