This study will explore why severe scarring of the liver (cirrhosis) develops so rapidly in hepatitis C-infected patients who have had a liver transplant and possibly in kidney transplant patients as well. The hepatitis C virus (HCV) can cause cirrhosis in about 20 percent of infected persons. Generally, it takes 20 years or more for cirrhosis to develop. After liver transplantation, however, patients may develop cirrhosis in as little as 5 years. Cirrhosis does not develop as rapidly in kidney transplant patients, but it may develop faster than in people who do not undergo transplantation. The study will look at the possible role of immune-suppressing medications given to liver and kidney transplant patients in increasing the severity of hepatitis C infection and in speeding the cirrhotic process.

Patients 18 years of age and older with chronic HCV infection who require a liver transplant for end-stage liver disease or a kidney transplant for kidney failure may be eligible for this study. Liver transplant patients are recruited from the Inova Fairfax Liver Transplant Center in Fairfax, Virginia, and from the Georgetown University Medical Center Liver Transplant Institute in Washington, D.C. Kidney transplant patients are recruited from the Transplantation Branch of the National Institute of Diabetes and Digestive and Kidney Diseases.

Participants undergo the following procedures:

• Regular care: As part of their regular transplant-related treatment, patients have a medical history, physical examinations and blood draws before their transplant and on regularly scheduled visits after the transplant.
• Blood draws for research: Special blood tests are done to measure the immune response to HCV. They measure the amount of HCV in the blood, the number of HCV strains present and how they change over time and the HCV antibodies in the blood.
• Liver biopsies: This procedure is done at 3 months, 1 year, 3 years and 5 years after the transplant to determine the extent of scarring of the liver and to study the immune responses within the liver, the proportion of liver cells infected with HCV and the presence of scar-producing cells. The biopsy is done during a 1- to 2-day inpatient hospital stay. The patients are given a sedative medication through a vein before the procedure. The skin over the biopsy site is numbed and the biopsy needle is passed rapidly into and out of the liver to collect a small sample of liver tissue for study.
• Apheresis: This procedure is done to collect a large number of white blood cells needed to test the immune response to the HCV. On the day before each liver biopsy, blood is drawn through a needle from a vein in one arm and run through a machine that separates and collects the white cells. The red cells and plasma are returned to the patient's body through the same needle or a second needle in the other arm.