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The Immune System and Cancer

Primary functions of the Immune system

The immune system defends the body against infection and sickness caused by bacteria, viruses, fungi, and parasites. It collects the body’s reactions and responses to damaged cells or infections. As a result, it is commonly referred to as the immunological response.

The immune system is crucial for cancer patients because,

  • Cancer can weaken the immune system.
  • Cancer therapies also weaken the immune system.
  • The immune system may aid in the battle against Cancer.

By spreading to the bone marrow, cancer can damage the immune system. The bone marrow produces blood cells that aid in infection resistance. This is most common in leukaemia and lymphoma, but it can also occur in other malignancies, where cancer can prevent the bone marrow from producing enough blood cells. Also, specific cancer treatments can temporarily weaken the immune system. This is because they can reduce the number of white blood cells produced in the bone marrow. Cancer treatments such as chemotherapy, targeted cancer drugs, steroids and radiation therapy generally affect the immune system. 

The immune system against cancer

While it is true that the immune system can become weak in a cancer patients. But at the same time, it helps cancer patient to fight against it. It is because, some immune system cells can identify cancer cells as abnormal and kill them. However, this may not be enough to eradicate Cancer. Some cancer treatments rely on the immune system to fight the disease.

The immune system is divided into two parts:

  • The safeguards we have had from birth (in-built resistant protection)
  • The defense mechanisms humans build after contracting certain diseases (acquired immunity)

Built-in Immune system

Innate immunity is another term for this. They can act very quickly. This built-in protection comes from various things like 

  • The barrier formed by the skin around our body, 
  • The inner linings of the guts and lungs which produce mucus and trap invading bacteria,
  • Hair that moves the mucus and the trapped bacteria out of the lungs,
  • Stomach acid that kills the bacteria,
  • Helpful bacteria growing in the bowel prevent other bacteria from taking over,
  • Urine flow that flushes out bacteria from the bladder and urethra, 
  • White blood cells called neutrophils can find and kill bacteria. 

A variety of factors can harm these natural defense mechanisms. Consider the following scenario:

  • Something like a trickle in your arm or a surgical wound can compromise the skin barrier.
  • A catheter inserted into your bladder can allow bacteria to enter the bladder and cause infection.
  • Anti-acid drugs for heartburn may work by neutralising stomach acid and killing bacteria.

Specific cancer treatments can also work through these defences. Chemotherapy reduces the number of neutrophils in the body momentarily, thus making it more difficult to fight infections and radiotherapy to the lungs can harm the hairs and cells that produce mucus, which helps eliminate pathogens.

Function of Neutrophils

Neutrophils are a type of white blood cell that plays a critical role in infection resistance. They can:

  • Stick to the invading bacteria, viruses, or fungus in sites of infection in the body.
  • Bacteria, viruses, and fungus are swallowed and chemically killed.
  • migrate to infected regions of the body

Doctors may diagnose you as neutropenic if your blood contains low neutrophils.

The number of neutrophils in the blood can be reduced by chemotherapy, targeted cancer medicines, and some radiation therapies. As a result, you may get more bacterial or fungal infections due to these therapies.

When receiving cancer therapy, you must understand the following:

  • In those with low neutrophil counts, infections can quickly become quite dangerous.
  • Antibiotics could save your life, so if you have a fever or feel ill, call your doctor or go to the hospital immediately. 
  • If your blood levels are low, you may require antibiotics to help prevent severe infection.

It is more common to fall unwell from bugs you bring with you rather than catching them from someone else. So, you shouldn’t have to avoid contact with your family, friends, or children after therapy.

Acquired Immunity

This is a type of immunological protection that the body develops after exposed to certain infections. The body learns to recognise each new kind of bacterium, fungus, or virus it encounters. As a result, the immune system will have an easier time fighting the insect the next time it invades the body. This is why some contagious diseases, such as measles or chickenpox, are usually only contracted once.

This sort of immunity is used in vaccinations. A vaccination comprises a small amount of a disease’s protein. This isn’t damaging, but it does help the immune system recognise the disease if it happens to come across it again. The immune response may then be able to prevent you from contracting the disease.

Small amounts of live bacteria or viruses are used in some vaccinations. Thus, these vaccinations are live attenuated. Hence, scientists have modified a virus or bacteria to cause the immune system to produce antibodies. So, a live vaccine will not infect you.

Other vaccines use dead bacteria or viruses or fragments of proteins produced by bacteria and viruses.

B cells and T cells

Lymphocytes are white blood cells that play a role in the immune system’s acquired response. Lymphocytes are divided into two types:

  • B cells
  • T cells

All blood cells, including B and T lymphocytes, are made in the bone marrow. They, like all other blood cells, must reach complete maturity before they can contribute to the immune response.

In the bone marrow, B cells mature. T cells, on the other hand, mature in the thymus gland. The B and T cells develop and then move to the spleen. Lymph nodes can be found in a vocabulary item. Hence, to fight illness, open a vocabulary item.

B cells

Antibodies are proteins B cells produce in response to invading germs or viruses. Each type of germ causes your body to create a distinct antibody (bug). The antibody binds to the invading bacterium or virus’s surface. This labels the invader so that the body recognises it as a threat and must be eliminated. Antibodies are also capable of locating and killing damaged cells.

The immune system’s memory is made out of B cells. When the same germ tries to infiltrate again, the B cells that create the appropriate antibody are ready. They can produce their antibodies in a concise period.

T cells

T cells come in a variety of forms, including:

  • helper T cells
  • killer T cells

Helper T cells stimulate B cells to produce antibodies and aid in developing killer cells. So, Killer T cells are immune cells that attack and kill the body’s cells that viruses or bacteria have infected. This inhibits the germ from replicating and infecting other cells within the cell.


Immunotherapy is a cancer treatment, It uses the body’s immune system to fight the disease. It hunts down and kills cancer cells using the immune system. Because cancer cells differ from normal cells, they are helpful in cancer treatment. Furthermore, the immune system is capable of identifying and eliminating aberrant cells. In the lab, scientists may create many molecules involved in the immune response. As a result, they can develop a variety of immunotherapies, including:

  • Monoclonal antibodies (MABs) recognise and attack particular proteins on the surface of cancer cells.
  • Vaccinations aid the immune system in identifying and combating Cancer.
  • Cytokines to assist and improve the immune system.
  • Change the genes in a person’s white blood cells via CAR T-cell treatment (also known as adoptive cell transfer).


CTCA. (2017, October 19). How does immune system work when it comes to cancer? Cancer Treatment Centers of America. https://www.cancercenter.com/community/blog/2017/10/how-does-the-immune-system-work-when-it-comes-to-cancer-its-complicated

How does the Immune System work. (2019, April 30). Cancer Research Institute. https://www.cancerresearch.org/en-us/blog/april-2019/how-does-the-immune-system-work-cancer

Immune response to cancer. (2018, May 8). Immunopaedia | Advancing global immunology education. https://www.immunopaedia.org.za/immunology/special-focus-area/2-cancer-tumours/immune-responses-to-cancer/

The immune system and cancer. (2020, June 7). Cancer Research UK. https://www.cancerresearchuk.org/about-cancer/what-is-cancer/body-systems-and-cancer/the-immune-system-and-cancer#:~:text=Cancer%20can%20weaken%20the%20immune%20system%20by%20spreading%20into%20the,making%20so%20many%20blood%20cells

National Cancer Institute. (2019, September 24). Immunotherapy for cancer. https://www.cancer.gov/about-cancer/treatment/types/immunotherapyNational Library of Medicine. (2018, October 1). Roles of the immune system in cancer: From tumor initiation to metastatic progression. PubMed Central (PMC). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6169832/

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