What is Immunology?

Immunology is all about how our bodies defend themselves against germs and other invaders. Imagine your body as a castle, and the immune system is the army protecting it from enemy attacks. This army has cells, tissues, and organs. They work together to keep you safe from viruses and bacteria.

But here’s where it gets really interesting: the immune system isn’t just about fighting off bad guys. It also helps our bodies accept or reject things that don’t belong, like when someone gets an organ transplant. See, when someone gets a new organ, their immune system might see it as foreign, think it is a threat and try to attack it, thinking it’s an invader. Immunology helps us understand how to prevent this from happening, so the new organ can stay and do its job without any trouble.

In simple terms, immunology is about how our bodies stay healthy. They do this by fighting off germs and ensuring that everything inside works well together.

What is Rejection?

Rejection is when the body’s defense system, called the immune system, treats a transplanted organ or tissue as if it doesn’t belong.  This can cause serious damage or even make the new organ stop working. To prevent this, doctors use special medicines called immunosuppressive medicines to calm down the immune system and stop it from attacking the new organ.

Types of Rejection

There are three types of rejection that transplant patients may experience:

1. Hyperacute Rejection: This is when rejection happens super quickly, within minutes to hours after the transplant. It’s not very common nowadays because doctors are really good at matching organs to patients. But if there’s a big mismatch in blood type or other cells in the body (called major histocompatibility complexes) it could still happen.
2. Acute Rejection: This is the most common type and it usually occurs within days to months after the transplant. Even if doctors give patients medicines to calm down (or “modulate”) their immune systems, some level of acute rejection can still happen.
3. Chronic Rejection: This is the trickiest type because it can take months or even years to show up. With chronic rejection, the organ slowly stops working as well as it should. It’s a more complicated situation because it can involve lots of different factors, not just the immune system.

Causes of Rejection

Rejection mostly happens because of genetic differences between the person who gets the organ (the recipient) and the person who donated it. This means the body might notice that something in the new organ is a bit different from its own.

HLAs (human leukocyte antigens) are like little tags or markers on our cells. They help our immune system recognize which cells belong to us and which ones do not. Imagine each cell in your body wearing a name tag. Your immune system looks at these name tags to make sure everything is okay. But when someone gets an organ transplant, the new organ might have different name tags (HLAs) than the rest of their body. This can confuse the immune system and make it think the new organ is an intruder.

If your immune system spots an intruder, it can fight against this new organ, leading to rejection. Even though doctors give patients medicines to calm down their immune systems, they can’t completely get rid of the risk of rejection.

Signs of Rejection and Monitoring

It’s really important for someone who has had a transplant to keep an eye out for signs that their body might be rejecting the new organ. Here are some things they should watch for:

• Pain or swelling where they had the transplant
• Fever
• Feeling tired a lot
• The organ not working as well as it should (like making less urine if it’s a kidney transplant)
• High blood pressure (for kidney transplants)
• Having trouble breathing (for lung transplants)

It’s also important for organ recipients to see their doctors regularly so they can do tests to make sure everything is going okay. These tests might include blood tests, imaging (pictures of the inside of the body), and sometimes biopsies, which is taking tiny pieces of tissue from the organ to check it under a microscope. This helps catch any rejection early so it can be treated quickly.

What is Tolerance?

Tolerance in transplant means that the body accepts the new organ or tissue without needing lots of medicine (immunosuppression) to keep the immune system calm. It’s like the body and the new organ becoming best friends, so the immune system doesn’t see it as a stranger anymore.

Scientists are working hard to figure out how to make this happen more often because it would make life a lot better for people who get transplants. They’re trying different methods, like using special immune cell types, certain therapies that change how the immune system works, and even new techniques like gene editing. The goal is to teach the immune system to treat the new organ like it belongs in the body, instead of trying to get rid of it.

Conclusion

Understanding how the body’s defense system works, which is called immunology, is really important for people who have had transplants. To make sure the new organ stays healthy and works well, it’s crucial for transplant patients to:

1. Know the signs that the body might use to tell them that it might be rejecting the new organ;
2. Take their immunosuppressive medicines as instructed by their doctors; and
3. Go to their doctor for check-ups and testing regularly.

Scientists are hopeful that as they continue doing research, they will find ways to enable the body to more easily accept new organs, making a huge difference in the lives of people who have had transplants.

This article is made possible by the support of ITB-MED LLC. 

Glossary

Acute Rejection: A type of rejection that occurs within days to months after a transplant. It is common but usually treatable if caught early.

Biopsy: A medical test involving the removal of a small piece of tissue to examine it for signs of disease or rejection.

Chronic Rejection: A type of rejection that happens over a long time, causing gradual damage to the transplanted organ.

Gene Editing (CRISPR): A technique used in research to alter genes to help the immune system accept transplanted organs.

Human Leukocyte Antigens (HLAs): Proteins on the surface of cells that are unique to each person and help the immune system recognize which cells belong in the body and which do not.

Hyperacute Rejection: A type of rejection that happens very quickly, within minutes to hours after a transplant, due to immediate blood clotting in the transplanted organ.

Immune System: A complex network of cells, chemicals, tissues, and organs that work together to defend the body against harmful invaders.

Immunology: The study of the immune system, which protects the body from harmful things like viruses, bacteria, and even transplanted organs.

Immunosuppressive Drugs: Medications that reduce the activity of the immune system to prevent it from attacking the transplanted organ.

Long-Term Immunosuppression: Ongoing treatment with immunosuppressive drugs to prevent rejection of a transplanted organ.

Monitoring: Regular check-ups and tests with healthcare providers to detect and treat any signs of rejection early.

Rejection: When the immune system attacks a transplanted organ or tissue, thinking it is harmful.

Tolerance: A state in which the immune system accepts the transplanted organ as part of the body and does not attack it, reducing the need for long-term immunosuppressive drugs.