The thymus is the organ in the body that has taken scientists the longest to study. It is only active from birth to adolescence. However, it plays a huge role in educating your body to fight infection and even cancer for the rest of your life. It is also vital for the exchange of chemicals or the body's endocrine system.
Read on to learn more about the role of the thymus in immunity, autoimmunity, and aging, and how certain diseases can affect this important organ.
History and Anatomy
The thymus is usually located behind the breastbone, in front of the heart, and between the lungs. However, in some people, this organ is found in the neck or upper chest.
While it may seem strange, it is part of the mystery of the organs that has puzzled scientists for centuries. Researchers began to understand some of the functions of the gland only about 50 years ago.
They are still not sure where he got his name from. Some experts say that the ancient Greeks who discovered this organ called it a thymus because its shape is similar to the leaves of thyme, a culinary herb. Others say that the name comes from the Greek word for soul, because the organ is next to the heart.
In any case, the thymus is considered an organ of the immune system. Like the tonsils and adenoids, it helps fight infection.
Unlike the heart or lungs, what the thymus does is not obvious. His work involves many tiny chemical processes.
There are many different cells within the thymus gland. This includes:
- Epithelial cells line all surfaces of the body and act as a protective barrier.
- Kulchitsky cells produce hormones , chemical messengers for the thymus and other cells.
- Thymocytes are cells that develop into mature T lymphocytes , specialized infection fighters.
- Dendritic cells are found in the skin and other tissues. They help protect against toxins and other foreign substances.
- Macrophages are cells They are sometimes referred to as the "garbage trucks" of the immune system. They eat the foreign bodies and clean the tumors.
- B lymphocytes are cells that produce antibodies, proteins that attack viruses and bacteria.
- Myoid cells are muscle cells. Scientists believe that they trigger an autoimmune response in muscle diseases.
This list gives an idea of how difficult the thymus gland is. Its role also changes throughout your life.
Changes with age
The famous Greek philosopher and surgeon Galen was the first to notice that the thymus changes with age. Galen wrote that it is large in newborn animals and becomes smaller when they become adults.
Your thymus gland reaches its maximum size when you are a teenager. Then it begins to slowly shrink. At the age of 75, the thymus turns into fat.
The term scientists use to describe this process of organ contraction is called involution. Doctors also know that severe stress can cause the thymus to contract. In fact, at the beginning of the 20th century, researchers did not believe that babies had a bigger thymus. When they performed autopsies on babies who died of diseases like diphtheria, they declined.
From the moment of conception to puberty, the thymus is very active. It serves both the immune and endocrine systems. It is a system that produces hormones, the body's chemical messengers.
To understand the immune system function of the thymus, it is necessary to know the difference between the two types of white blood cells. These are T lymphocytes (T cells) and B lymphocytes (B cells). These cells are like the "special forces" of the immune system.
T cells versus B cells
T cells are also known as thymic lymphocytes. They help fight foreign invaders in the body, such as bacteria, viruses, and toxins. They can also identify and attack cancer cells.
B lymphocytes or B cells play a different role. They make proteins called antibodies and use them to kill specific invaders.
T cell boot camp
When early adopters and immune system advocates need extra help, they turn to T cells. They are made by bone marrow, the spongy tissue of bones. When T cells are young or immature, they travel through the bloodstream to the thymus gland.
The thymus has two lobes. One of them is a kind of training ground for T cells. This is where they mature into special disease-fighting cells with different functions.
Types of T lymphocytes
The T cells of the thymus become three main fighters against diseases of the immune system:
- Cytotoxic T cells : these cells are responsible for the direct destruction of infected cells.
- Helper T cells : These cells cause B cells to produce antibodies. They also charge T cells and make them attack foreign invaders.
- Regulatory T cells : These cells function as "police". They suppress both B cells and other T cells if they mistakenly cause harm to the body.
Positive and negative options
The part of the thymus gland called the cortex is where T-cell training takes place. Here, young T cells learn to detect antigens or toxins associated with cells and foreign matter. This process is called "positive selection."
Once the T cells recognize certain pathogens, they move to another part of the thymus called the medulla. Here they undergo a different type of training: "negative selection." They become familiar with antigens in the body, so they do not attack or harm them.
This prevents autoimmune disorders. These are medical conditions where something goes wrong and your cells attack your body's tissues and cells instead of foreign invaders.
Not all T cells go through this selection process. Only about 2% end up with both a positive and a negative selection.
The survivors are then exposed to the hormones produced by the thymus to complete their training. They are then released to do their job.
The role of mature T cells
These well-trained cells circulate in the bloodstream or wait in the lymph nodes for the immune system to sound an alarm. Mature T cells play a vital role.
T cells are part of the adaptive immune system. It is the immunity your body develops after your immune system has been exposed to an infection, vaccine, or foreign substance.
T cells are trained to recognize and eliminate external threats that overcome the body's first line of defense. When killer cytotoxic T cells recognize a foreign invader, they take over the cell and destroy it with helper and regulatory T cells.
This is what is known as cellular immunity or the use of immune cells to fight infection.
A negative selection process takes place in the thymus. It is used to kill T cells that have become too reactive and too bound to other molecules. The weeding process detoxifies T cells that can attack the body's own tissues and cells. This prevents the development of autoimmune disorders.
Scientists used to think that aging was simply a wear and tear on the body. They now understand that aging is an active chemical process.
Some scientists believe that the shrinkage of the thymus may be the cause of the aging process.
As the thymus contracts, your immunity decreases. This is why older people are more likely to get sick or develop diseases such as cancer. They are also less likely to respond to vaccines. Currently, research is looking for ways to slow the contraction of the thymus, boost immunity, and slow down the aging process.
This line of research is very new. In a small study of nine healthy men, researchers used growth hormones, steroids, and diabetes medications to restart the thymus.
For more than two years they have been doing blood and imaging tests on men. They also measured their epigenetic age. That is how old the body is according to biology. The men were between 51 and 65 years old,
The researchers say that after a year, the men had more T cells and a stronger immune system. According to biology, their bodies were about 2.5 years younger than their chronological age.
The thymus gland produces several hormones, including:
- Thymopoietin and thymulin: these hormones participate in the process by which T cells turn into different types of disease fighters.
- Thymosin: this hormone improves the response of the immune system. Thymosin also stimulates growth hormones.
- Thymic Humoral Factor: These hormones enhance the immune system's response to viruses.
The thymus also produces small amounts of hormones in other parts of the body. These include melatonin, which helps you sleep, and insulin, which helps control blood sugar.
The thymus gland can be affected by many conditions, from genetic diseases to cancer in the elderly. This can lead to immune and autoimmune problems.
Thymus hypoplasia / aplasia
DiGeorge syndrome is a rare developmental disorder in children that affects the thymus gland. This causes the gene to mutate.
In children born with this disease, the thymus is underdeveloped or there is no thymus gland at all. This leads to serious problems with the immune system and a high risk of infections. They also have thyroid problems or hypoparathyroidism .
Thymic follicular hyperplasia
In this condition, the thymus becomes swollen and inflamed. This can happen with autoimmune diseases such as:
- Lupus – When the immune system attacks the joints, skin, kidneys, blood cells, brain, heart, and lungs.
- Erythematous disease: when the immune system attacks connective tissue.
- Myasthenia gravis (MG): when the immune system attacks the musculoskeletal system.
- (for more details on MG, see below)
- Rheumatoid arthritis: when the immune system attacks the joints.
- Graves disease : when the immune system attacks the thyroid gland.
- Sjogren's syndrome: when the immune system attacks the cells that produce saliva and tears.
Cysts are abnormal growths filled with fluid. They are tiny, less than 3 centimeters (cm). Usually this is not a problem.
Thymus cysts are often only found when your doctor is treating you for something else. An example is lung cancer screening. In rare cases, thymic cysts can hide the cancer.
Thymomas are tumors that arise in the thymus gland. They can be harmless or cancerous. They can also occur in the neck, thyroid gland, or lungs.
Other tumors that can develop in the thymus include thymic lymphomas, germ cell tumors, and carcinoids. Symptoms of thymoma often depend on the location of the cancer. For example, the chest can cause shortness of breath.
Doctors can find these tumors because the patient has developed what is known as paraneoplastic syndrome . These rare autoimmune diseases occur when T cells try to fight a certain type of cancer. Cells mistakenly attack parts of the brain and spinal cord, nerves, and muscles.
These are some of these states:
- Myasthenia gravis (MG) : This is a condition in which your muscles become weak and tired and you lose the ability to control them. This autoimmune disease occurs in 25% of people with thymomas.
- Pure red blood cell aplasia : This is a condition in which T cells attack young red blood cells. This causes severe anemia, a lack of red blood cells that carry oxygen. This occurs in about 5% of people with thymomas.
- Hypogammaglobulinemia : This is a condition in which the B cells do not make enough antibodies. This occurs in about 10% of people with thymomas.
Thymomas can also cause a condition called thymoma-related multi-organ autoimmunity. This condition is similar to the rejection seen in some people after organ transplants. In these cases, the tumor produces T cells that attack the human body.
Under certain conditions, surgeons can remove the thymus with a thymectomy. One of the reasons is that the child was born with heart disease. The thymus is near the heart and is large in babies. Therefore, surgeons must remove it to operate on the baby's heart.
Surgeons may also remove the thymus if you have cancer or have been diagnosed with myasthenia gravis. Research shows that about 60% of people with myasthenia gravis achieve remission when the thymus is removed.
Surgery is usually performed between puberty and middle age to avoid the possible consequences of removing the thymus too early.
Consequences of removing the thymus
The thymus gland is important because it trains the immune system to fight infection. Most of this learning takes place before birth. However, research has linked removal of the thymus in babies with an increased risk of infections and autoimmune diseases.
Children are also at increased risk for thyroid disease, asthma, allergies, and possibly cancer. This is because T cells play a vital role in cancer prevention. There is also some evidence that removal of the thymus can cause premature aging of the immune system.
The thymus gland plays a vital role in teaching the immune system to defend the body against infection, including cancer. This process begins from the moment of conception. The thymus reaches its maximum size during adolescence. Then it begins to slowly shrink.
Some scientists believe that the natural contraction of the thymus causes aging of the immune system. So as we get older, we get sick more often and respond less to vaccines. Researchers are investigating ways to slow down the thymus twitch process.
Get the word of drug information
The thymus is important for both the immune and endocrine systems. The microchemical processes it controls are very complex. Until recently, researchers did not have the scientific knowledge to understand many of them.
They are still learning. The sharp rise in autoimmune diseases has increased scientists' interest in the thymus gland. Even more intriguing is its role in the aging process. So it is likely that in the future we will learn even more about the function of the thymus and its proper health.
Frequently asked questions
The thymus gland exists to train our immune system to fight disease, infection, and cancer. This process begins even before birth. The gland continues to grow until age 13, after which it begins to contract very slowly.
The thymus gland has two possible locations. It is usually located in front of the heart, but in some people, the thymus is located in the neck or upper chest.
Symptoms of thymus cancer include shortness of breath, cough (which may include bloody phlegm ), chest pain, trouble swallowing, loss of appetite, and weight loss. It can be the result of a tumor in the thymus gland pressing against nearby blood vessels, airways, or esophagus.