Efficacy of Low Dose, SubQ Interleukin-2 (IL-2) to Expand Endogenous Regulatory T-Cells in Liver Transplant Recipients

A common complication of organ transplantation is 'rejection' of the transplanted organ. This occurs when the body's immune system tries to attack (or reject) the transplanted organ.

Drugs known as immunosuppressants (anti-rejection medications) are prescribed for patients after transplantation to prevent rejection. But, anti-rejection medications are associated with significant side effects including high blood pressure, high blood sugars, and high cholesterol - all of which may increase the risk of heart and vascular complications. Anti-rejection medications also increase the long-term risk of some types of cancer.

Sometimes, liver transplant patients who stop taking anti-rejection medications do not experience rejection of their transplanted liver and the liver keeps working. These patients are said to "tolerate" the transplanted liver, and this condition is referred to as "tolerance". Doctors are working to learn more about why some liver transplant patients develop tolerance after receiving a transplant, while others do not.

Studies have shown that patients who develop "tolerance" have an increase in a type of immune cell called regulatory T-cells or "Tregs". This means Tregs may be important in preventing rejection of a transplanted organ.

Studies have also shown that a human cytokine (a type of protein), called interleukin-2 (IL-2) aids in increasing the number of Treg cells in the body, and IL-2 has been given to patients to successfully treat disorders of the immune system such as graft vs host disease - a serious condition sometimes seen in patients after bone marrow transplantation.

The purpose of this investigation is to study if low dose IL-2, given to liver transplant patients by subcutaneous (under the skin) injections, over a 4 week period of time, will cause an increase in the number of Treg cells in the blood.

In addition, investigators will learn about the kinds of side effects low dose IL-2 will cause and how severe those side effects will be.