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Doctors tell us that you’ll develop immunity to your new organ at 120 days post transplant. What does this actually mean, and how will you know? That is a good question, which we’ll try to answer here. Let’s take a look at what happens in your body as you get closer to being fully immunized.

How does the immune system develop immunity?

Immunity is your body’s natural ability to fight off or resist infection. It’s the reason why colds don’t usually last long, and why some people never get chicken pox as kids. The immune system is complicated, but it’s designed to remember how to fight off diseases that you’ve had before. The more stem cells you have, the more immune cells you can make. That’s why immunity develops quickly when you have lots of stem cells. These cells must train or “learn” how to fight diseases from your stem cells, which take time. It usually takes a few months for immunity to develop, so patience is key! Someday, you’ll know that you’re fully immunized.

What is Immune Tolerance?

Another way your body protects you from infection is through a process called immune tolerance. This is when specific immune cells recognize an antigen (a foreign substance), and then they “tolerate” that antigen. A tolerance is like a truce between two sides. So, the immune system doesn’t attack the “tolerant” antigen anymore. This is a huge part of why transplanted stem cells can produce tolerance in your body. Immune tolerance is helpful for transplanted stem cells because it allows your body to recognize the foreign stem cells, but not attack it. This allows transplanted cells to continue to do their job. Another way that your body can tolerate transplanted stem cells is through the HLA gene. HLA is found on the surface of your cells and is responsible for helping the immune system recognize foreign cells.

The Immune System and Stem Cell Transplants

The process of creating immunity via the adaptive response is a lengthy one. Your body must receive large amounts of immune cells to adequately develop immunity. Stem cells are the ones responsible for this, so as soon as they are transplanted into your body, there is a rush to create more immune cells through the adaptive response. This can take a while, in which case your immune system will need time to recognize the foreign stem cells and make antibodies to attack them. In most cases, this immunity takes 120 days. Immune responses are complex, and there are variables that can affect the timing. Some of these variables are the type of transplant, the age of the patient, and the patient’s own immune response.

How can you tell if you’re developing Immunity?

If you’re on the immunotherapy path, you will notice some changes in your health. You might feel better, or be less symptomatic. Some patients notice that when their immune system is trained, they don’t have to take as many pills. When you’re immunized, you’ll also be able to stop taking your immunoglobulin (IG). IG is a protein that is used to “tag” antibodies to the immune system. This tag is a way of keeping the antibodies from being destroyed, so you don’t lose them. Immune responses are complex, and there are variables that can affect the timing. Some of these variables are the type of transplant, the age of the patient, and the patient’s own immune response.

Symptoms of Improper Immunity Development in SCID Patients

There are a few symptoms you may notice when your immunity is not developing properly. If you develop any of these, you should get medical attention immediately. These include: – Fever – Any time you have a fever, get it checked out! It could mean something is wrong with your health, but it could also mean that your immunity is underdeveloped. – Poor appetite – If you don’t feel like eating, or eating a lot less than normal, it could be an indication of immunity underdevelopment. – Fatigue – If you feel weak all the time, it could mean you’re not creating enough antibodies. – Serious infections – If you’re getting sick often, or with serious infections, it could mean that your immunity is not sufficient.


It’s a good idea to visit your doctor regularly to check on the status of your immunity. He or she can also give you guidelines for how long you should wait to visit again. Immunity takes time to develop, and it’s important that your body has enough time to develop antibodies. Immunotherapy is a lengthy process, so don’t feel bad if it takes a while to develop. If you notice any symptoms of immunity underdevelopment, report them to your doctor. You’ll want to get them looked into as soon as possible.

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