VOL 23
Issue 11v28
Str Date: 2023.332.

Immunology: the study of the immune system

Immunology: the study of the immune system

With the triple threat of RSV, COVID, and the flu, can our immune systems adequately protect us? Immunology is the medical and biological sciences branch that studies the immune system.

The Immune system

The immune system is a combination of molecular and cellular components. The immune system is divided into two mechanisms: the non-specific immune mechanism and the responsive immune mechanism. Immunology includes the study of structure, function, blood banking, organ transplantation, and disorders of the immune system.

Figure 1: Complex network of the immune system

Innate immunity

The innate immune response is the non-specific immune system, the first line of defense against pathogens. The innate immunity system is what you are born with and comprises cellular, chemical, and physical defense against pathogens. The innate immune system responds immediately against pathogens to prevent them from spreading and moving into other regions of the body.

The cellular non-specific immune system includes mast cells, basophils, neutrophils, and macrophages which kill the harmful microorganism (Janeway et al., 2001)

The physical barriers include skin, saliva, etc., which are ready-to-go components of the innate immune system and protect the body from the initial stage of the disease.

The humoral non-specific response system includes enzymes, endogenous messenger substances, or other non-cellular components of the immune system.

Adaptive immunity

The adaptive immune response is the second line of defense and reacts slower than the innate immunity system. The major components of the adaptive immune system are B lymphocytes and T lymphocytes, as well as their antibodies and antigens. Antibodies target foreign pathogens freely moving in the bloodstream, and lymphocytes target the colonized pathogen cell and can directly kill the infected cell.

History of Immunology

 In 1796 Edward Jenner introduced artificial immunity against disease by using a cowpox injection to protect people from smallpox disease. But scientifically, immunology was not oriented until scientists recognized that there is some proliferating microorganism that causes many diseases, and the body has some cellular component that responds and destroys antigens within the body.

Components of the immune system

(Cologne, 2006) The components of the immune system are:

  • Antibodies
  • White blood cells
  • Lymphatic system
  • Bone marrow
  • Complement system
  • Spleen
  • Thymus


Antibodies are the immunoglobulins that help the body fight against microbes or the toxin they produce, and they are derived from plasma cells, which in turn are formed from B lymphocytes. Antibodies attack the microbes by recognizing substances (antigens) marked on the microbe’s surface as foreign, then antibodies kill those microbes.

White Blood Cells

White blood cells (phagocytes) are critical components in our immune system as they kill or engulf foreign invaders and bacteria to protect the body from disease. Phagocytes have three main groups; monocytes and macrophages, dendritic cells, and granulocytes:


Under the microscope, monocytes have a large kidney shape nucleus, also known as the largest type of phagocyte. Monocytes are found in the bloodstream and circulate in the body; they attack in such a way that when microbes infect any tissue, they leave the bloodstream and enter the tissue; thus, they kill the microbe or foreign invader.


Macrophages originate from monocytes and play a crucial role in the phagocytosis of microbes, foreign substances, and cellular debris. Macrophages are termed differently based on location in such a way that macrophages present in Central Nervous System are known as microglia and in the liver, known as Kupffer cells. In addition, macrophages help initiate the adaptive immune response by activating T cells.

Dendritic cells

Dendritic cells play a significant role in the innate and adaptive immune response as the immature cell moves through the bloodstream. When the cell becomes mature and enters into the lymphoid region, such as the spleen, gut-associated lymphoid tissue, and lymph node activates the T-cell. Then it starts an adaptive immune response system.


Granulocytes combine basophils, eosinophils, and neutrophil granules in the cytoplasm. Neutrophils are found in large numbers, a group of phagocytes with dense granules in their cytoplasm, and include neutrophils (short lived-cells), eosinophils, and basophils. Neutrophils are a significant part of white blood cells found in the bone marrow.

Lymphatic system

The lymphatic system, also known as a sub-system of the circulatory system of vertebrates, consists of a complex network of delicate tubes, vessels, organs, and tissue. They play a vital role in the body by maintaining the fluid level in the body by collecting the excess material from tissue and organ and release into the bloodstream. It also can fight against infectious particles by removing cells known as lymphocytes. It can also deal with cancerous cells and absorb fats from the intestine. The lymphatic system consists of lymph nodes (called lymph glands), lymph vessels (that carry lymph), and lymphocytes (white blood cells).

                                                                                            Figure 2: B Lymphocytes


The thymus is a bi-lobed gland and is responsible for the production of a hormone known as thymosin. Thymosin, in return, produces T cells and different proteins on the T cell surface, such as CD4, CD8, etc. In the thymus and bone marrow, B and T cells and lymphocytes mature, then enter into lymph nodes and spleen, where they are activated when required by the immune system.


Spleen is located behind the stomach, and its critical function is to filter blood. The spleen filters blood so healthy red blood cells pass through the spleen, but macrophages engulf damaged cells.

Bone marrow

Bone marrow is essential in producing red blood cells that carry oxygen, white blood cells, and platelets.

Complement system

A complement system utilizes a combination of proteins to defend your body. It helps clean up damaged cells and helps your body heal after an injury.

What is immunotherapy?

Immunotherapy, also known as immune-oncology (cancer immunotherapy), is a cancer treatment in which the immune system initiates a response to control and eliminate cancer (Bulk et al., 2018). One of the most famous patients of immunotherapy was former president Jimmy Carter. In Mr. Carter’s case, a drug called pembrolizumab helped his immune system target melanoma. Another benefit of immunotherapy is that it is less toxic than other cancer treatments because it uses the body’s power to treat cancer rather than chemical treatment methods (Markman, 2021).

Final Thoughts

Whether by accident or treachery, humankind is more likely than not to face some new virus that our body will have to adapt to. Our immune system can be trained to fight off disease and viruses. New Immunology breakthroughs, like immunotherapy, hold promise for the future.   Immunology, the study of the immune system, is more than just science; it’s survival.







Bulk J., Verdegaal E. and Miranda N. (2018). Cancer immunotherapy:  broadening the scope of targetable tumors. National Library of Medicines, doi: 10.1098/rsob.180037.

Markman M. (2021). Immunotherapy. Cancer Treatment Center of America.

Janeway CA Jr., Travers P. and Walport M. (2021). Immunology: The immune system in Health and Disease. Garland Sciences.

Cologne. (2006). What are the organs of immune system? Institute for Quality and Efficiency in Health care.

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