The immune system – a brief overview

There are a lot of posts in this blog that require at least a minimum awareness of immunology. So, I decided to tell you what immunology really deals with and how you can understand previously discussed topics with this knowledge.

So, what is immunology? Basically, it is studying body’s defence mechanism. It is important to understand this in both healthy as well as diseased conditions because the body has different components “active” in different scenarios.

What are the different things involved in the immune system? Many components of the immune system are actually cellular in nature and not associated with any specific organ but rather are embedded or circulating in various tissues located throughout the body. There are some organs which are responsible for the production of these cells. They include thymus, bone marrow (Bone marrow, the soft tissue in the hollow centre of bones, is the ultimate source of all blood cells, including lymphocytes), spleen, tonsils, lymph vessels, lymph nodes, adenoids etc. The cells are in turn responsible for the production of different kinds of biomolecules (Eg: Antibodies)

The key to a healthy immune system is its remarkable ability to distinguish between the body’s own cells, recognized as “self,” and foreign cells, or “nonself.” The body’s immune defences normally coexist peacefully with cells that carry distinctive “self” marker molecules. But when immune defenders encounter foreign cells or organisms carrying markers that say “nonself,” they quickly launch an attack.

In abnormal situations, the immune system can mistake self for nonself and launch an attack against the body’s own cells or tissues. The result is called an autoimmune disease. Some forms of arthritis and diabetes are autoimmune diseases.

Where are the cells concentrated? Lymph nodes, which are located in many parts of the body, are lymphoid tissues that contain numerous specialized structures.

  • T cells from the thymus concentrate in the paracortex.
  • B cells develop in and around the germinal centers.
  • Plasma cells occur in the medulla.

Lymphocytes can travel throughout the body using the blood vessels. The cells can also travel through a system of lymphatic vessels that closely parallels the body’s veins and arteries.

Cells and fluids are exchanged between blood and lymphatic vessels, enabling the lymphatic system to monitor the body for invading microbes. The lymphatic vessels carry lymph, a clear fluid that bathes the body’s tissues.

The immune system stockpiles a huge arsenal of cells, not only lymphocytes but also cell-devouring phagocytes and their relatives. Some immune cells take on all intruders, whereas others are trained on highly specific targets. To work effectively, most immune cells need the cooperation of their comrades. Sometimes immune cells communicate by direct physical contact, and sometimes they communicate releasing chemical messengers.

Why are we using proteins and cells of the immune system for research purposes? If evolution is so perfect and we are the ultimate answer to all animals, why are we being plagued by so many diseases and disorders?

Unfortunately, we are not the only products of evolution. Viruses, bacteria and other harmful microbes have also had similar treatment from nature and they are equipped with arsenals that have the capacity to evade our immune systems. As for why we need to do research on the immune system, for the simple reason that we will have more information on how to tackle the diseases and disorders that are life threatening.

What kind of research is going on? Scientists are now able to mass-produce immune cell secretions, both antibodies and lymphokines, as well as specialized immune cells. The ready supply of these materials not only has revolutionized the study of the immune system itself but also has had an enormous impact on medicine, agriculture, and industry.

Read about monoclonal antibodies here. Ankur has provided a good description of its use and production.

Research into the delicate checks and balances that control the immune response is increasing knowledge of normal and abnormal immune system functions. Someday it may be possible to treat autoimmune diseases such as systemic lupus erythematosus by suppressing parts of the immune system that are overactive.

Scientists are also devising ways to better understand the human immune system and diseases that affect it. For example, by transplanting immature human immune tissues or immune cells into SCID mice, scientists have created “humanized” mice, a living model of the human immune system. Scientists are manipulating the immune system of humanized SCID mice to discover ways to benefit human health. Humanized mice are also being used in research on transplantation and autoimmune and allergic diseases, and to manufacture molecules that help regulate immune system function and immune tolerance.

In pioneering experiments, scientists are removing cancer-fighting lymphocytes from the cancer patient’s tumor, inserting a gene that boosts the lymphocytes’ ability to make quantities of a natural anticancer product, then growing the restructured cells in quantity in the laboratory. These cells are injected back into the person, where they can seek out the tumor and deliver large doses of the anticancer chemical. This is called cell therapy.

Now that you have enough information for understanding the immune system, you can appreciate all its myriad applications. There are several ways by which the cells, organs and even protein molecules of the immune system can be manipulated for the betterment of the society.

Hope you enjoyed this. If there is something you have difficulty understanding or you would like us to give you information on a specific topic, please don’t hesitate to ask.

Peace

Avi

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