Your immune system protects your body from viruses and disease. It is an essential part of the body such that without it humans cannot survive. The functioning of the immune system depends on several factors such as the presence of a chronic illness or mutation, but one very important factor which affects the degree of immune response is genetics. Recent studies have shown that people belonging to different genetic descents have different immune responses. Researchers of the Institut Pasteur in France found that people having African ancestry immune activity responds differently in comparison to Europeans. Click here for more information.
What is your immune system?
The immune system is a complex network consisting of cells, tissues, and organs that work in harmony with each other to protect the body from foreign invaders. These invaders could be microbes like bacteria, fungi, viruses, and parasites that can cause disease and infection. The human body is vulnerable to millions and trillions of these so-called foreign invaders all the time. It is the job of our immune system to prevent them from entering it and if they somehow succeed then fight and destroy them. Our immune system is unique, complex and well-adapted.
- Complexity of the immune system The immune system is dynamic and complex in itself. Since there is a great number of disease-causing microbes out there it can remember millions of foreign particles individually and react to each one of them in a very specific way.
- The immune system is diverse Our immune system is so diverse and developed that it produces different secretions in response to different foreign bodies to prevent them from disrupting the normal functioning of our body.
How does the immune system work?
One very important thing about the working of the immune system is the difference between ‘non-self’ and ‘self’ substances.
- Non-self refers to substances found on foreign bodies. These are called antigens and are proteins found on the surface of microbes. When a microbe enters the body, the immune system detects these proteins and immediately acts to fight and destroy them.
- Self refers to similar proteins found on the surface of the body’s own cells and are not harmful. Fortunately, the immune system can distinguish between self and non-self-proteins. However, sometimes certain factors trigger the immune system to act against the body’s cells by identifying them as ‘non-self’. Such an action is called an autoimmune reaction.
What are the important organs of the immune system and how do they work?
The immune system is composed of entire organs and lymph vessels as well as individual cells and proteins. All of these organs and cells work together in coordination to protect the body from disease and infection.
- First line of defense (skin and mucous membrane of organs) The outer and inner surface of the human body and organs are the first defense barrier in the body. This barrier is comprised of skin and mucous membranes of organs. They form a protective wall against microbes that is supported by several other substances such as mucus and cilia (tiny hair-like projections) in bronchi (airways leading to the lungs), enzymes in saliva and tears, acid in the stomach and normal flora (harmless bacteria). [Note: Mucous traps the microbes, debris and other invaders whereas cilia move them up and out of the system]
- Primary lymphoid organs The primary lymphoid organs are the next most important part of the immune system. They include the bone marrow and thymus. These organs produce different defense cells called “leukocytes” also called white blood cells. They are found in blood vessels and lymph vessels.
- Bone marrow: The bone marrow, found in the center of bones produces defense cells called “lymphocytes”. These cells coordinate immune response by attacking and destroying infected cells in the body.
- Thymus: Thymus is a gland found just below the neck. It’s function is to educate T-lymphocytes and make them able to distinguish between self and non-self substances.
- Secondary lymphoid organs The secondary lymphoid organs include the spleen, lymph nodes, and tonsils. These are the organs where the leukocytes perform their functions and are in continuous contact with foreign invaders and non-self-substances.
- Spleen: The spleen is located under the rib cage just above the stomach. It acts as a filter for the immune system. It recycles old red blood cells and stores platelets and leukocytes.
- Lymph nodes: These are located in different areas of the body such as neck, jaw, collarbone, armpits and groin. Their function is to filter out foreign particles from the blood and lymph fluid and strengthen immune response.
- Tonsils: Tonsils are masses of soft tissues that are located at the back of the throat. Their function is to trap foreign invaders like bacteria and viruses which may enter the body while breathing.
- Immune cells Immune cells are the cells produced by the bone marrow. They are called white blood cells or leukocytes. These cells are of two types; lymphocytes and phagocytes.
- Lymphocytes: Lymphocytes are of two types T- and B- lymphocytes.
- T-Lymphocytes: Those lymphocytes that travel from the bone marrow to the Thymus to become mature are called T-lymphocytes. Their function is to destroy infected cells and to direct other cells to initiate an immune response.
- B-Lymphocytes: Those lymphocytes that stay in the bone marrow are called “B-lymphocytes”. They produce antibodies, substances that attach to foreign antigens. Each B-lymphocyte produces one specific antibody against a specific antigen. These antibodies are a part of substances called “Immunoglobulins”, that mark and kill germs.
- Phagocytes: They constitute the second type of leukocytes. Their job is to surround the invading particles detected by lymphocytes. This is followed by engulfing and eating them.
- Lymphocytes: Lymphocytes are of two types T- and B- lymphocytes.
What are the various types of immunity?
A person’s immune system becomes stronger with time as it matures from childhood to adulthood and gets exposed to more pathogens, thus developing more immunity. When a certain antibody is produced in the body against a particular antigen, a copy of that antibody is stored in the system. This is to deal with the same antigen more quickly when it attacks the body again. That’s why some diseases such as chickenpox occur only once in a lifetime as the stored antibody from previous attack kills the antigen second time even before it attacks. There are three types of immunity found in the human body:
- Innate immunity: Humans by birth have this type of immunity i.e., natural immunity against foreign particles. This includes the first line of defense i.e., skin and mucous membranes of organs. Innate immunity involves a generalized response to antigens. If pathogens are successful in dodging innate immunity than acquired immunity becomes active.
- Acquired immunity: This is also called adaptive immunity. This type of immunity develops as the body matures and becomes exposed to more and more pathogens. A library of antibodies is formed against particular antigens which become active when a specific antigen attack again.
- Passive immunity: This refers to immunity borrowed from some other source. When a person’s immune system cannot produce antibodies itself then it borrows it from another source. For e.g. newborn baby acquired passive immunity from his mother’s via the placenta. Antibodies move through the placenta from the mother’s immune system to provide immunity to the baby.
What weakens your immune system?
Different people have different immune systems in terms of strength. Some people naturally have a weak or exceptionally strong immune system. The normal working of the immune system is very important to protect the body from disease or illness. However, there are some factors which can weaken the immune system, making you more susceptible to diseases and infections:
- Stress: Stress has a very negative effect on the working of the immune system. When your body is under some kind of stress, a stress hormone ‘cortisol’ is released. It reduces the production of ‘good prostaglandins’ (hormones that coordinate normal immune functioning). As a result, the immune system gets disturbed, making you susceptible to infections like cold and flu.
- Unhealthy diet: Consumption of large amounts of refined sugars, processed foods, carbonated drinks and food containing chemicals and preservatives can weaken your immune system to a great deal according to research.
- Excessive consumption of alcohol: Consumption of alcohol in very large amounts can reduce the ability of leukocytes to kill foreign germs and invaders thus making you vulnerable to infections.
- Inadequate sleep: Like all other systems of the body the immune system also needs rest. When you do not get enough sleep, your immune system becomes weak with time. Poor sleep reduces the production of immune cells like T-lymphocytes, thus compromising your ability to fight disease.
- Inactive lifestyle: A sluggish, lazy or inactive lifestyle can be very damaging for your immune system. Reports show that people who exercise for 20 mins daily have a much stronger immunity as compared to those who do not exercise at all.
- Unnecessary medication: The use of excessive medications like painkillers and antibiotics can decrease immune functioning. This is because antibiotics reduce the production of cytokines, the hormonal messengers of the immune system, ultimately reducing immune strength.
How to strengthen your immune system
In the fast pace of life, humans forget or somehow ignore the importance of keeping their body healthy and nourished. Healthy diet and active lifestyle are very important for the normal functioning of the body and more specifically the immune system. Here’s how you can strengthen your immune system:
- Keep your gut healthy. Most of the immune cells in your body live along the path of your gastrointestinal tract which constitutes about 70% of your immune system. The intestinal lining is involved in secreting antibodies and producing immune cells. You must take several steps to keep your gut health in check such as
- Take probiotics, good bacteria required for normal intestinal health
- Avoid intake of refined sugars, processed foods, and carbonated drinks
- Avoid taking foods that your gut cannot tolerate such as dairy foods.
- Take your vitamins. Vitamins like Vitamin D and C are very important for the health of your immune system. Ask your doctor to check your vitamin levels and take supplements to prevent any deficiencies. Adequate vitamin levels strengthen the immune system and prevent the occurrence of infections.
- Incorporate power foods into your diet. Power foods refer to whole unprocessed foods which are very good for immune health. These include vegetables like mustard, lettuce and collard greens, mushrooms and a lot of garlic. Garlic contains a substance called allicin which helps the immune system in fighting bacteria.
- Keep your hormones balanced. Excessively high or low levels of hormones like estrogen and progesterone can damage immune function. Get your hormone levels checked frequently to keep them at an optimum level.
- Exercise daily. Incorporating cardio exercise for 30-40 minutes at least five days a week can boost blood circulation and flow of lymphatic fluids. Good flow in the lymphatic vessels improves immune functioning.
Your immune system and Fighting Cancer?
The human immune system can detect non-self substances like bacteria, viruses, fungi, parasites and even unhealthy cells like cancer cells. The detection of such substances by immune cells triggers a series of reactions and pathways. This ultimately leads to the destruction of the foreign invader or non-self-particles. Your immune system has the ability to detect and fight abnormal cancer cells to some extent. However, when cancer spreads further or directly to immune system organs such as bone marrow, it weakens the immune functioning. Similarly, some cancer treatments like chemotherapy and radiotherapy reduce the level of leukocytes which are very important for normal immune health. However, recently scientists have developed immunotherapies for cancer treatment. This treatment enhances and boosts the immune system to fight cancerous cells in the body. It depends on the immune system’s ability to detect and differentiate between normal body cells and cancerous cells. Thus, the immune system plays a very significant role in fighting against chronic diseases like cancer.