Your Body’s Defenders: The Role of Cells, Proteins, and Organs in Keeping You Healthy

This is the first post in a two part series on the immune system, to learn what happens when the immune system is not working check out Part 2 (When the Defenders Go Awry).

We rely on our immune system all the time, but what does it actually do and how does it work?

The immune system is made up of a variety of cells, proteins and organs all throughout our bodies. These respond to different kinds of threats ranging from a cold virus, to germs, from a cut, to cancer cells. The immune systems main job is to recognize things that should not be in our body and to remove them. Most often these are foreign germs or substances from outside our body, but they also protect us from abnormal cells that form inside our body such as cancer cells.

The cells of your immune system

White Blood Cells are the heavy lifters of your immune system. They are constantly circulating through your blood stream as they watch for and respond to any threats. They are also located in your lymph nodes where they help to destroy and remove substances they recognize as being harmful for your body. There are five different types of white blood cells and they all have a different role in your body’s immune response

• Monocytes: These cells are on the lookout for invading cells and mount a response to infection and inflammation. They envelope and remove the foreign substance or damaged cell. They can also produce cytokines. Some will alert other cells that they are needed in the area, while others help with healing by letting the body know it is time to stop it’s inflammatory response.
• Lymphocytes: These cells are identified as being either “B cells” or “T cells.” Simply put, B cells make antibodies, while T cells destroy infected cells.
• Neutrophils: These are the first cells called in by the body to fight an infection. They work to attack and remove the infection.
• Basophils: These cells will attack organisms they don’t recognize as being part of your body. They are also part of the body’s allergic response when they release histamine. They also release heparin which helps to prevent your blood from clotting.
• Eosinophils: These cells help to prevent any foreign substance to be able to grow inside your body’s cells.

The proteins of your immune system

• Antibodies: Any foreign substance that enters the body is considered an antigen (think virus, bacteria or even your own cells that become cancerous). Your immune system has the amazing ability to learn. It does this by creating antibodies in it’s B cells. Once it has fought off a foreign substance, antibodies against that substance will continue to circulate throughout your body, ready to recognize and attack if that same foreign antigen ever enters your body again. They are found everywhere from your bloodstream to your lungs, mucus, saliva and breast milk.
• Cytokines: These are small proteins that allow cells within your immune system to communicate with one another. They are able to stimulate and stop inflammation, stop cells from replicating, and signal the body to create more of specific blood cells.
• The Complement System: Complement is a component of normal blood plasma. It is made up of proteins that help with the inflammatory response to kill certain bacteria.

The organs of your immune system

• Lymph Nodes: Lymph is cell waste product left behind by the capillaries. Lymph is then picked up by the lymph vessels and passes through a series of lymph nodes on its way to exit the body. The lymph nodes filter the lymph and contain white blood cells that destroy unhealthy and foreign cells and particles. They also create antibodies against them.
• Spleen: Your spleen is a filter for your blood. It recognizes red blood cells that are no longer working and has white blood cells to destroy them. As it filters your blood it also recognizes foreign antigens and releases white blood cells to produce antibodies to fight the infection.
• Tonsils: These are strategically located to be able to catch germs as they enter your nose and mouth and destroy them before they get any further into your body. They contain a large amount of white blood cells.
• Thymus: The thymus is responsible for making T cells. They form in the bone marrow but then travel to the thymus to develop and mature before they can fight as part of your body’s immune response.
• Bone Marrow: Your bone marrow is where all of your blood cell formation takes place. Even if the cells travel to other places to mature, they start production in the bone marrow.
• Skin: The skin is obviously very important as a barrier in preventing germs from ever entering into our bodies. But it also contains immune cells within it’s layers. These are continually monitoring the environment on your skin and are also ready to jump in to defend your body when the skin is injured by a cut and to help with healing.
• Mucosa Immune System: This is the immune defense we see in epithelial cells that are vulnerable to infection because of their location so close to the outside of the body. These include areas such as the gut, the upper respiratory tract and lungs, the eyes, and the vagina and uterus. It includes T cells and antibodies as part of it’s immune defense.
• Peyer Patches: This is part of the gut-associated lymphoid tissue and helps to protect the body from ingested antigens and help to make antibodies.

Two parts of your immune system

You have two “subsystems” within your immune system. The innate and acquired. Your innate immune system is manned by your neutrophils. Your acquired response utilizes B Cells and T Cells as they can create antibodies to respond to a specific invader and they can remember germs that they have fought off before. Your innate immune system is what you are born with. Your acquired immune system is what the cells of your immune system teach themselves as they learn and grow as they fight off different and new foreign antigens. Pretty amazing, right?