What Is The Immune System?

Our body’s defense system is actually what immune system is all about. A well-maintained health is a name given to a proper working immune system.

The immune system is fighting against all the pathogens, infections, viruses, bacteria, etc. It acts as a bodyguard of the human body and as a protective agent.

The immune system against invaders:

The immune system is a network of cells, organs, and tissues found in the body to fight diseases and cancers. Immune system and immune responses are the series of steps that attack the harmful organisms and the substances lurking in the body systems and destroy them. It acts as a home defense, especially in cold and flu season.

Significance of the immune system:

The significance is marked by the example of those people who are born with problems in their immune system (like immunodeficiency). Such people are infected very easily. Thankfully many individuals can be treated easily with bone marrow transplants allowing them to activate their working immune system.

The human body is supposed to protect itself particularly against the minor bacteria and the viruses (contrarily known as germs) that cause disease. Else they will find an easy environment to settle down and multiply due to shelter and free food.

Components Under The Umbrella Of The Immune System:

The bodily system protecting our body from foreign or domestic organisms include the following:

  • Lymphocytes or white blood cells (act as Knight) comprising of B cells (which make antibodies attack bacteria and noxious stimuli) and T cells (which help to destroy infected or cancer causing cells).
  • Thymus (small organ situated beneath the breastbone. It can trigger and conserve antibodies production resulting in muscle weakness.
  • Spleen (large organ on the left side just above the stomach and below the ribs, containing White Blood Cells to fight disease. It also disposes deteriorated and old blood cells
  • Lymph nodes (Bean-shaped structures to manufacture and store cells to fight infections. When a body is fighting any disease, these nodes get enlarged.
  • Deposits of lymphoid tissues (as in bone marrow that is yellow tissue present in the center of bone and produce WBCs and gastrointestinal tract)
  • Antibodies (series of proteins)
  • Macrophages (significant cells of immune system that are held responsible for identifying, engulfing and destroying the target cells)
  • hormones (lymphokines-protein mediators released by lymphocytes on contact with a toxin and produce macrophage activation and immune response, Thymosin-produced by thymus to encourage lymphocyte activity)

*Although there are hormones like steroids and corticosteroids that suppress the immune system.

Obstruction to infections:

There are numerous ways to protect the body from infections. One of the easiest and effective way is to create a physical barrier such as skin that blocks the germs.

Similarly, some substances produced by the body like saliva and tears that neutralize the germs escalating the barrier effect.

In the same way, in lungs ‘mucous’ coats the lining of lungs to capture the foreign bodies.

Security breach:

Sometimes the barrier effect is weak, and these methods mentioned above don’t work hence, the body searches for alternative methods like some specialized cells to combat the infections.

These specialized cells are part of the tissue barriers hence they identify the invading cells immediately as they reach here. While some cells move around in the body or locate themselves in lymph nodes or spleen while waiting for the signs of disease or infection to reach via the bloodstream.

Mechanism of action:

Immune system gives resistance to an infection or disease. The immune system has two parts:

  1. Innate immunity
  2. Adaptive immunity

Innate immunity:

As the name says “innate” meaning “present from birth.” It is furnished relatively by the non-specific mechanism. Such as Rapid inflammation that occurs immediately after an injury or trauma. It hinders the entrance and initially spreading of the disease, a process called “Phagocytosis” takes place. In this quick response process, the specialized cells called phagocytes follow and engulf the infected germs.

Adaptive immunity:  

In contrast to the innate mechanism, adaptive immunity is more specific and selective in its action to particular germs that are more difficult to deal with the innate immunity. It is a rather slow process i.e. it doesn’t respond instantly. But since it remembers the germs that it has encountered previously, so it fights immediately the next time they infect the body.

There are two kinds of adaptive immunity response:

  • Humoral immune response
  • Cell-mediated immune response

Humoral immune responses are active against the substances that display their action outside the cells such as the bacteria and toxins. Proteins called antibodies bind to and kill the germs

Cell-mediated response resists the pathogens that hide and reside within the cells like viruses. They may also kill cells that are changing forms or make irregular amounts of normal cells as in the case of cancers.

Vaccines use the adaptive immune system by tricking the body in creating an adaptive response without the danger of any infection.

What’s Good And What’s Bad For Our Immune System:

Harmful For Immune System:

  • Malnutrition
  • Inadequate sleep
  • Stress

Boosters Of Immune System:

  • Vitamin D
  • Nutrients with antioxidant capacity (Vit C, E, selenium, beta-carotene, and carotenoids)
  • Positive attitude and staying happy

Immuno-oncology: Affinity of Immune system in cancer

Cancer and its treatment may weaken the immune system by reaching in the bone marrow although the immune system has great potential to combat the tumors. Last 30 years of research on immuno-oncology have shown proven evidence that tumors can easily be detected by the immune system and its development is controlled through a process called immunosurveillance. The specificity of tumor response of immune system resides in recognizing the antigens (toxins) of the tumor.

However, in many cases malignant progression interferes with an effective antitumor response and tumor elimination.

Significance of the immune system to cancer patients:

Immune system is important to cancer patients in numerous ways because:

  • Cancer weakens the immune system
  • Cancer treatments may disturb and slows down the immune system
  • Immune system may help fight cancer big time

Cancer and its treatment weaken the immune system:

As cancer spreads to the bone marrow, it starts to weaken the immune system. Bone marrow forms leukocytes (white blood cells) that combat infections. Weakening happens in case of leukemia (cancer of blood-forming tissues) and lymphoma (cancer occurring in lymphocytes)

Chemotherapy and radiotherapy also frail the immune system as it destroys the normal white blood cells too along with the tumor cells made in the bone marrow. These therapies can also lower neutrophil (which are also white blood cells) count. Hence one may develop bacterial and fungal infections after the therapy.

The main parts of immune system are:

  • Immunity we have since birth
  • The protection we induce from being exposed to diseases

B and T cells Of Lymphocytes:

As mentioned before B cells and T cells are two main types of lymphocytes.

B-cells mature in the bone marrow and make proteins called antibodies and hence react against invaders (bacteria/viruses)

T-cells mature in the thymus and are of two different types:

  • Helper T cells
  • Killer T cells

The Helper T cells assist B cells in making antibodies and help the killer cells to develop.

Killer T cells help destroy cancerous or infected cells that are infected with viruses and other pathogens. It is these cells that are held responsible for killing tumor cells.

Cancer Treatments Using Elements of The Immune System:

In treating cancer, some of the elements of the immune system are used.


A biological therapy using natural body substances or drugs to treat cancer. Since, the cancer cells are different from the normal cells s they are easily detected by the immune system.

Different chemicals part of the immune system are made in the laboratory. They include interferon, interleukin 2 and monoclonal antibodies (all antibodies are of the same type).


The immune system is the first defense mechanism against pathogens. It fights whatever it takes to defend the body from toxins. Specialized cells, tissues and organs are given this task.

The immune system has a very deep connection with cancer and its treatment. The immune system has a strong potential of decreasing tumor cells by an adaptive immune response and T lymphocytes.

Most doctors agree to the fact that reducing stress through meditation and massage can be very relaxing and can boost the immune system against all odds.