A retrospective evaluation of HLA-A, B and -DRB1 matching in liver transplantation

Vaccination for hepatitis C virus: closing in on an evasive target

Hepatitis C virus (HCV) infects more than 170 million people globally and is a leading cause of liver cirrhosis, transplantation and hepatocellular carcinoma. Current gold-standard therapy often fails, has significant side effects in many cases and is expensive. No vaccine is currently available. The fact that a significant proportion of infected people spontaneously control HCV infection in the setting of an appropriate immune response suggests that a vaccine for HCV is a realistic goal. A comparative analysis of infected people with distinct clinical outcomes has enabled the characterization of many important innate and adaptive immune processes associated with viral control. It is clear that a successful HCV vaccine will need to exploit and enhance these natural immune defense mechanisms. New HCV vaccine approaches, including peptide, recombinant protein, DNA and vector-based vaccines, have recently reached Phase I/II human clinical trials. Some of these technologies have generated robust antiviral immunity in healthy volunteers and infected patients. The challenge now is to move forward into larger at-risk or infected populations to truly test efficacy.

Risk factors for acute rejection in living donor liver transplantation

The influence of human leukocyte antigen (HLA) compatibility and lymphocytotoxic crossmatch on acute rejection in living donor liver transplantation (LDLT) has not been well examined. We analyzed 100 consecutive adult LDLT cases. The patient and graft survival rates and post-operative complications were assessed. The relation between the incidence of acute rejection and some clinical factors including HLA and lymphocytotoxic matching was also examined. Patients with HLA DR zero mismatching (p = 0.02) or negative T-lymphocytotoxic crossmatch (p = 0.04) had a significantly lower chance of rejection within 6 wk after LDLT. However the results had no influence on the patient survival. Our results demonstrate that in LDLT, a graft from an HLA-DR zero mismatching or negative T-lymphocytotoxic crossmatch might be advantageous because of the decreased probability of early acute rejection.

Allograft rejection in pediatric liver transplantation: Comparison between cadaveric and living related donors

The aim of this study was to determine whether living related liver transplantation has an immunological advantage compared with cadaveric liver transplants in children. The records of 100 pediatric primary liver transplant recipients performed between January 1992 and December 1998 at the University of California, San Francisco Medical Center, were reviewed retrospectively. Ten children who died or required a second graft within the first 14 post-operative days were excluded from this study group. Two children with combined kidney-liver transplants were also excluded. As a result, the study group included 51 children in the cadaveric liver transplantation (CLT) group and 37 children in the living-related liver transplantation (LRLT) group. Until 1995, primary immunosuppression consisted of cyclosporin A, azathioprine and steroids. Since 1995, primary immunosuppression consisted of cyclosporin A, mycophenolate mofetil and steroids. Actuarial graft survival rates at 1, 2 and 5 yrs were 90%, 80.9% and 80.9% in the CLT group vs. 94.6%, 91.6% and 78.5% in the LRLT group, respectively (NS). Rejection was diagnosed in 40 of 51 cadaveric first grafts (78.4%) and 25 of 37 living-related primary grafts (67.6%). Rejection episodes were diagnosed greater than 1 yr post-transplantation in 11 of 51 cadaveric first grafts (21.6%) and none of 37 living-related primary grafts (0%) (p < 0.05). LRLT succeeded in reducing the immunosuppressive therapy compared with CLT at 24 months after transplantation (p < 0.05). The overall incidence of rejection and graft survival rate were comparable in CLT and LRLT; however, rejection episodes in LRLT recipients diagnosed greater than 1 yr post-transplant were significantly fewer than CLT recipients. LRLT have a partial immunological advantage compared with CLT.

Detection and characterization of HLA class I molecules in the supernatant of an hepatocarcinoma cell line and of EBV-transformed B cell lines

Human leukocyte antigens (HLA) class I molecules can be detected in "soluble" form in the supernatant of cultured cell lines and in serum and plasma of humans. These "soluble" HLA class I molecules are assumed to play a role in liver transplantation. In order to define the nature and composition of HLA class I molecules found in solution, we studied the HLA class I production of an hepatoma carcinoma cell line (HepG2) and of EBV-transformed B-cell lines. Based on molecular weight (MW) analysis, it was demonstrated that different forms of HLA class I molecules were produced by HepG2 cells and EBV B-cells. Monoclonal antibodies (mAbs) specific for HLA class I alleles were able to recognize the mature 45 kDa form, but failed to interact with the 42 kDa and 39 kDa MW forms of HLA class I. Of these different MW forms of HLA class I molecules the mature 45 kDa product was found predominantly to be associated with subcellular vesicles whereas the alternative MW forms of 42 kDa and 39 kDa exist as truly free entities in supernatants.