What is tolerance?

Tolerance after solid organ transplant is defined as the absence of anti-donor immuno-reactivity without the need for immunosuppression. Operational tolerance refers to the clinical state of being off all immunosuppression after solid organ transplant with maintained normal transplant organ function. This state has been difficult to achieve clinically in a predictable and stable fashion.

Why does ISOrTT exist?

The goal of ISOrTT is to prospectively document the outcomes of patients from multiple centers across the world that have successfully been maintained off immunosuppressive drugs after organ transplantation.

How do I get involved?

See our contact page for email access to our coordinating center staff.

The International Solid Organ Transplant Tolerance Registry would like to thank the following sponsors:



Welcome to the International Solid Organ Transplant Tolerance (ISOrTT) Registry

Achieving and understanding patients' ability to undergo solid organ transplantation without the need for ongoing immunosuppression is a key goal of transplantation research. The ISOrTT Registry Website exists to fulfill two key missions. The first is to establish a multi-center, international database registering patients who have been successfully maintained off immunosuppression for at least one year after transplantation. Also, ISOrTT will serve to facilitate enrollment of interested patients into appropriate studies of transplant tolerance and serve as a resource on tolerance studies and literature for interested patients, physicians, and families.


How do I participate?

Patients and families who are interested in participating should contact their transplant center and physicians so that their medical team can participate in enrolling them into the registry. Of course, you are also welcome to view the materials on the public website and contact us directly for any questions you may have. There is no charge or payment for participating.

Physicians and transplant centers are encouraged to participate and enroll their patients by contacting our Off Site Coordinator and becoming a Participating Institution. Depending on your center or location, institutional review board may be required. The goal of the Registry is to include as many transplant centers as possible and to allow access to the de-identified database for research or clinical use. There is no cost to centers and participation is voluntary. Data entry and access to your center's data will be provided by a secure access user name and password. Please contact us for any questions and we will assist you in the process.

Who is Eligible?

Although the ability to have satisfactory organ function in the absence of immunosuppression has been reported more frequently after liver transplantation, organ transplant tolerance in theory may be seen after any solid organ transplant. This Registry will include patients who have maintained normal organ function after withdrawal from immunosuppression for at least one year after any solid organ transplant. With patient informed consent, the Registry will then be able to prospectively follow these patients on an annual basis and prospectively document the natural history of their transplant organ function and any need for subsequent re-instatement of immunosuppression.