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Immunosuppression plays a crucial role in the success of a solid organ transplant. It helps prevent a transplant recipient’s body from rejecting a donor organ, leading to better outcomes.

Through the pioneering work of Thomas E. Starzl, MD, PhD, and others, immunosuppression became a critical part of the transplant process. It can help prevent acute and chronic organ rejection.

More than 1 million organ transplants have occurred in the United States, and immunosuppression helps ensure their success.

What Is Immunosuppression?

Immunosuppression in organ transplantation is the process of suppressing an organ recipient’s immune system through drugs and other means.

Without immunosuppression, the recipient’s immune system would recognize a donor organ as foreign tissue and attack it. This typically would lead to rejection of the donated organ. Immunosuppression helps prevent organ rejection.

Immunosuppression became a key part of organ transplantation within the last 60 to 70 years, thanks in large part to Dr. Starzl.

Dr. Starzl — known as “The Father of Transplantation” — began testing the antirejection drug azathioprine in the early 1960s. He developed a protocol for implementing azathioprine and the steroid prednisone to prevent organ rejection. His findings led to the creation of an immunosuppression protocol for human patients.

Early antirejection efforts were less successful in human liver transplant patients than in kidney transplants. In the late 1970s, a breakthrough came with a new antirejection drug named cyclosporine. Dr. Starzl began using cyclosporine in liver transplant patients in 1978, and the drug dramatically reduced organ rejection. Cyclosporine is still used today to prevent rejection in kidney, liver, and heart transplants.

In the late 1980s, Dr. Starzl’s work showcased the success of another immunosuppressive drug called tacrolimus.

Tacrolimus helped to improve survival in organs that previously had high rejection rates. It is still used today to prevent rejection in patients who receive heart, lung, kidney, liver, and pancreas transplants.

How Does Immunosuppression Work?

The immunosuppression process can begin before or immediately after the transplant surgery. It typically continues throughout the recipient’s life after transplant.

There are three major stages of immunosuppression:

• Induction — Induction is the delivery of high-intensity immunosuppression either immediately before or after transplant. This can involve either immunosuppressive drugs or antibodies. The goal is to prevent acute rejection of the organ.
• Maintenance — The maintenance phase of immunosuppression involves using antirejection drugs over the long term (typically lifelong). This prevents rejection from occurring over time.
• Anti-rejection — Anti-rejection immunosuppression involves using immunosuppressive drugs or antibodies in the case of an acute organ rejection. This can stop the rejection.

The specific course of immunosuppression varies by patient. Medicines and dosages can depend on factors like the type of organ being received, the likelihood of rejection, and more.

Why Is Immunosuppression Important for Transplant?

Immunosuppression is a crucial part of the organ transplant process because it can help prevent organ rejection. This can help lead to both organ survival and patient survival.

Over the years, immunosuppression has helped significantly improve patient and graft survival rates. The specific rates of patient and graft survival vary by the type of solid organ transplant, but they continue to climb.

A 2022 study in The Annals of Thoracic Surgery reported that graft survival in heart transplants steadily increased over 30 years. The study found that immunosuppression was linked with a 15-year increase in graft survival.

Other studies have found similar associations between immunosuppression and better transplantation outcomes.

A 2020 report in Pharmacotherapy analyzed long-term trends with immunosuppression and transplant outcomes. The study reported that innovations in induction and maintenance immunosuppression over the decades helped lead to lower organ rejection rates and better graft survival.

What Are the Challenges of Immunosuppression?

Immunosuppression can lead to better transplant outcomes, but some challenges and complications can occur. As the name implies, these medicines suppress your immune system — your body’s first line of defense against disease.

Because transplant recipients take immunosuppressants over the long term (often for life), they may be at higher risk for:

• Cancer — Long-term immunosuppression can affect the body’s ability to recognize and kill cancer cells.
• Infections — Similarly to cancer, immunosuppressants affect your body’s ability to fight off infections. This can put you at higher risk for bacterial, fungal, parasitic, and viral infections.

Other potential complications of immunosuppression include:

• Gastrointestinal symptoms.
• High blood pressure.
• High cholesterol.
• Kidney failure.
• Medication side effects.
• Type 2 diabetes.

Transplant centers are taking steps to minimize the risks and maximize immunosuppression results.

According to the Pharmacotherapy study, transplant teams have become more multidisciplinary. This means pharmaceutical specialists work alongside transplant specialists to develop individualized immunosuppression plans for patients.

There has also been research into using novel therapies to reduce the need for long-term immunosuppression. This research is ongoing, but it could lead to fewer complications in the future.

A Transplant Recipient’s Guide to Immunosuppression

If you have received an organ transplant and are on immunosuppressants, the key to success is consistency. You need to take your pills daily, as recommended by your transplant team, to prevent organ rejection. Don’t stop taking any of your prescribed medications or change the dosage unless your care team specifically tells you to.

To establish consistency, try using a daily pill container and taking pills at the same time daily. Make sure you get your prescriptions refilled in time to avoid any lapses in coverage.

Ask your doctor about any drugs, food, or drinks that could cause a bad interaction with your antirejection medication, such as grapefruit or grapefruit juice.

Other things you can do to protect yourself while on immunosuppressants include:

• Getting vaccinated — Because people on immunosuppressants are at higher risk of infections, staying up to date on vaccines is key. Ask your doctor about recommended vaccines to lower your infection risk, and get them on the recommended schedule.
• Seeing your doctor — Go back for follow-up visits with your transplant team as recommended. See your other doctors, such as your primary care provider, regularly to stay on top of your overall health.
• Practicing healthy habits — Eating healthy, exercising, and getting enough sleep can all benefit your immune system.
• Washing your hands — Proper hand hygiene can help you lower your risk of infections. Wash your hands frequently with soap and water, scrubbing for at least 20 seconds before rinsing.