Immune System

What is your immune system?

The immune system is your first line of defense against infections, both viral and bacterial, as well as other diseases. The immune system, which is made up of special cells, proteins, tissues, and organs.

How does it work?

Your immune system works through a series of actions known as the immune response. This response attacks invaders including organisms and substances that attack and your body’s systems and cause illness and disease.

Three Types of Immunity

Blood Cells
One can see red blood cells, several white blood cells including lymphocytes, a monocyte, a neutrophil, and many small disc-shaped platelets. By Bruce Wetzel (photographer). Harry Schaefer (photographer) (Image and description: National Cancer Institute) , via Wikimedia Commons

Adaptive Immunity

This type of immunity is very active, developing throughout our lives as we are exposed to various germs and diseases, as well as when we are vaccinated. Adaptive immunity involved the parts of our immune system that are in our blood.

Most people know that their blood is made of white and red cells. The white blood cells are part of your immune system. They are also known as leukocytes.

There are two basic types of leukocytes:


Phagocytes are cells that destroy invading organisms. The most common type of phagocyte is the neutrophil. Neutrophils fight bacterial invaders.


Lymphocytes are created in the bone marrow. If they stay in the bone marrow to mature, they become B lymphocytes (think B for bone marrow). B lymphocytes produce antibodies.  Antibodies are special proteins that lock onto specific antigens. Antigens are foreign invaders in the body. These antibodies stay in your body, preventing you from getting sick with the same disease in the future. An example of this is the chickenpox. Once you get chickenpox, you usually won’t get it again.

Immunizations utilize this function to prevent certain diseases. Most immunizations are an inactive virus or disease which doesn’t make you sick but still causes your body to produce antibodies, protecting you from getting sick with that disease/illness in the future.

B lymphocytes are great at finding invaders, but they can’t destroy them on their own. They need the help of another type of lymphocyte.

While the B lymphocytes are maturing in the bone marrow, there is another type of lymphocyte that leaves the bone marrow early and head for the thymus gland, where they mature into T lymphocytes (think T for thymus). T lymphocytes destroy the invaders the B lymphocytes have identified. Sometimes, people call T lymphocytes, “killer cells.” Another thing that T lymphocytes do is signal other cells in the immune system, such as phagocytes, to do their job.

Antibodies can neutralize toxins. They can also activate a group of proteins called a complement, which assists in killing viruses, bacteria, and infected cells.

Innate Immunity

Everyone is born with natural immunity. This is known as innate immunity. This type of immunity protects one species from getting illnesses of another. For example, humans don’t get heartworm and Dogs don’t get HIV.

Some of our innate immunity comes from parts of our immune system that form a barrier between us and potential invaders.

One of these barriers is our skin. If you get a cut, the defensive barrier is broken. As the cut heals, you are vulnerable to infection. Thankfully, immune cells on the skin attack invading germs, protecting us.

Mucous membranes are also part of our innate immune system. These gooey barriers to germs and other invaders line our nose, throat and gastrointestinal tract. As you breathe, the mucus membranes that line your nose trap air pollutants. It’s your first line of defense.

Passive Immunity

In the early years of life, we are most vulnerable to infections and viruses because we haven’t yet developed a strong immune system that recognizes and destroys invaders. Thankfully, babies can get antibodies in their mother’s breast milk. These antibodies protect them against many early childhood illnesses and infection.

What if it doesn’t your immune system doesn’t work right?

There are 4 main things that can go wrong with the immune system:

  • Immunodeficiency is when part of the immune system isn’t working properly.

Primary Immunodeficiency is when you are born with the problem.

Acquired (or secondary) immunodeficiency develops later. They can be the result of malnutrition, disease, or medication such as chemotherapy or steroids.

  • Auto immune disorders are when the body’s own immune system attacks its own tissue as if it were a foreign invader. Examples of autoimmune disorders are rheumatoid arthritis and lupus.
  • Allergies happen when the immune system over-reacts to antigens (allergens), producing excess histamine, causing a variety of symptoms ranging from mild itching to life-threatening anaphylaxis. Associated disorders include eczema, allergies to food, environmental allergies, and asthma.
  • Cancers of the immune system include lymphoma and leukemia. Both are common childhood cancers. Thankfully, most cases of these cancers in kids are curable with current treatments. Leukemia involves out of control growth of leukocytes. Lymphoma involves lymphoid tissues. Both cancers weaken the immune system making it harder for the patient’s body to fight off infection.

How does cancer treatment affect your immune system?

Medications like chemotherapy and radiation destroy cancer cells. Unfortunately, they also destroy healthy cells like those found in bone marrow and other parts of the immune system. Patients lose neutrophils, which fight infection-causing bacteria. Doctors call this “neutropenia.”

Immune System
By Volker Brinkmann – (November 2005). “Neutrophil engulfing Bacillus anthracis”. PLoS Pathogens 1 (3): Cover page. DOI:10.1371. Retrieved on 2009-01-04., CC BY 2.5,

Boosting your Immune system

Doctors sometimes give patients non-specific immunotherapies alongside traditional cancer treatments such as chemotherapy and radiation. This improves their overall immune system function.

An example of this is the Neulasta shot which prevents/treats neutropenia. This is a colony-stimulation factor, a man-made form of a protein which stimulates the growth of white blood cells. There are no common side effects of Neulasta. My husband, Dan, experienced one side effect that occurs in less than 30% of patients. The side effect was bone pain. This is caused by the rapid production of white cells in the bone marrow.  It feels like growing pains, only much worse. Dan was in the worst pain of his life.

When someone is in active cancer treatment, they must be more careful about coming into contact with bacteria and viruses. One person’s minor cold can put a cancer patient in the hospital since they are immunocompromised and can’t fight the illness. Cancer patients often decline to shake hands or attend social functions when their immune system is compromised.

Can your immune system fight cancer?

Immunotherapy is one of the most recent developments in cancer treatment. The goal is to stimulate a patient’s immune system, causing it to be more effective in fighting cancer.

Cancer cells grow and spread because the immune system doesn’t recognize them as foreign, Immunotherapies are inactivated forms of cancer cells or proteins that are unique to cancer cells. These are introduced to the patient’s immune system to try to “teach” it to recognize cancer cells and attack them. These therapies aren’t without side effects, and they only work for certain patients with certain cancers. For those patients, immunotherapy can be a powerful; weapon in their cancer battle.

Immunotherapy is opening doors to new ways of fighting cancer. With every new discovery, researchers gain a greater understanding of the enemy we are up against, and the possibilities for eliminating that enemy.


I am an author, writer, and speaker and homeschooling mom of 3. Since my husband, Dan was diagnosed with stage IV lung cancer in 2012, I’ve focused my writing and speaking on helping cancer patients and their families advocate for themselves and live life to the fullest, despite their illness.

My goal is to help people face cancer with grace.

My book Facing Cancer as a Friend: How to Support Someone Who Has Cancer, is available on

The Erickson Family, August 2016. Photo By Jim Bovin

2 thoughts on “Immune System”

  1. So, don’t take this creepy or anything, but I just love the photo of your family sitting there in the park. (I think it’s a park, but that’s a pretty big open space in the background.) It’s a photo that shouts out to me. And I may hear it wrong, but what it says to me is that these are five individuals who are also one family. And I love that!

    Anyway, stay strong. You’re awesome.

    • Thanks, John. You’re reading it right. We are all, very unique individuals that fit together like a wonderful jigsaw puzzle. 🙂

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