What Are Immunosuppressants?

In the vast range of medicines and drugs developed by mankind, there are some that seem rather counterproductive at first glance. These drugs inhibit some essential aspect of our body, but are still used on a large scale all around the world. One type of such drugs are immunosuppressants.


Immunosuppressants are drugs that suppress or weaken our immune system, as the name implies – “immune” + “suppress”. These drugs are usually not specific and affect the immune system as a whole, thus weakening it overall. However, if our immune system is supposed to protect us, then the use of immunosuppressants seems counter-intuitive.

These drugs are mainly used in the case of organ transplants and autoimmune diseases. Autoimmune diseases occur when our immune system begins to attack our own cells. In such a case, it is necessary to weaken the immune reaction in order to reduce and control the damage being caused to our own body.

In the case of organ transplants, the body eventually recognizes that the organ is not part of itself and attacks it. This leads to a rejection of the transplanted organ. In such a case, immunosuppressants are very important, as they lead to a milder reaction from the immune system. The milder the immune rejection, the longer the transplanted organ can function properly.


Photo Credit : Max Pixel

Mechanism of Immunosuppressants

Different types of immunosuppressants work by inhibiting different parts of the immune system. Most of them target the T-lymphocytes, since these are mainly responsible for carrying out our cell-mediated immune response.

Drugs that fall under the category of calcineurin inhibitors target the compound calcineurin. This compound catalyzes reactions that are integral in the activation of our T cells.

T cells are a critical part of our adaptive or acquired immune system. This is the more advanced part of our system and requires activation. Therefore, blocking it leads to a suppressed immune response, as T cells play an important role in transplant rejection and autoimmune diseases.

Another category of immunosuppressants prevents the proliferation or multiplication of our T cells. These drugs target a protein kinase, which is integral in the progression of the cell cycle. Thus, this approach also leads to immune system suppression.


Some drugs block the proliferation of T-cells

There is also a class of drugs known as glucocorticoids, which inhibit the genes that code for molecules that are important in cell proliferation (interleukins). These affect the T and B lymphocytes, thus affecting our humoral and cell-mediated immunity.

Antibodies can also be used as immunosuppressants. They can be designed and immunized to bind to specific receptors, thus blocking the production of essential chemicals, such as interleukins.


The use of immunosuppressants is essential, especially in cases of transplants. Almost 90% of transplants are rejected without the use of these drugs. However, no matter how essential they are, they also have some notable side effects

Suppression of the immune system leaves it weak and vulnerable. It becomes open to infections, and sometimes even opportunistic organisms. These are organisms that are usually found in some part of the body, but can become a nuisance in any other part. Weakening of the immune system also makes it inefficient in fighting the formation of benign and malignant tumors, thus leading to increased chances of cancers.


Immunosuppressants make us vulnerable to cancers

Being potent drugs, these medicines may also lead to negative drug interactions if the patient is consuming other drugs as well. Therefore, care must be taken to ensure that such a potentially deadly blunder does not occur.

Immunosuppressants are an important part of certain medical procedures. Without them, carrying out any transplants would be next to impossible, as the body would start rejecting the new organ within days. However, immunodeficiency is the necessary evil in this scenario. After all, we can’t have our own cake and eat it too!


  1. NPS MedicineWise
  2. The National Kidney Foundation
  3. Wikipedia.org
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About the Author:

Mahak Jalan has a BSc degree in Zoology from Mumbai University in India. She loves animals, books and biology. She has a general assumption that everyone shares her enthusiasm about the human body! An introvert by nature, she finds solace in music and writing.

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