The role of the histocompatibility laboratory in desensitization for transplantation:

HLA antibody detection and characterization by solid phase immunoassays: methods and pitfalls

Solid phase immunoassays for the detection and characterization of HLA-specific antibodies provide greatly increased sensitivity, specificity, and time and reagent efficiency, compared to the traditionally used cell-based methods. Testing is performed using commercially available test kits. The assays are of two general types: enzyme-linked immunosorbent assays and multianalyte bead. The types vary in both sensitivity and equipment requirements.While these assays afford great improvement over the cell-based assays, they can be confounded by interference from substances within the serum that result in high background reactivity. The high sensitivity of the assays also makes them more susceptible to environmental factors and operator variability. The user must be aware of the capabilities of the various formats, the factors that can affect test results, and lot to lot variability of any single product. Knowledge of the characteristics of each product and thorough and accurate analysis of the results are essential to the utility of these assays.

Does lymphocyte cross-matching predict acute rejection and graft survival in liver transplantation?

INTRODUCTION

The role of lymphocyte cross-matches (LCM) remains controversial in the liver transplant field. The aim of this study was to correlate the risk for acute rejection episodes and graft survival in liver transplantation with pretransplant LCM results.

PATIENTS AND METHODS

We enrolled 184 adult liver transplantation patients, excluding pediatric and second grafts. The 129 living donor and 55 deceased donor liver transplantations were divided into 2 groups: LCM (+); (n=20) and LCM (-); (n=164).

RESULTS

There were no differences in the demographic features, such as gender and recipient age, original disease, Model for End-Stage Liver Disease score, donor type, number of human leukocyte antigen mismatches, and cold ischemia times. There were no hyperacute rejection episodes in the LCM (+) group. Also, posttransplant complications such as acute rejection episode, biliary complication, or hepatic artery thrombosis were not different. Acute rejection episodes occurred in 5.0% of the LCM (+) group and 15.2% of the LCM (-) group (P=.317). Bile duct complications after transplantation arose in 20.0% of the LCM (+) group and in 32.9% of the LCM (-) group (P=.312). The 2 groups showed no difference in graft survival rate analyzed by the Kaplan-Meier method according to LCM results.

CONCLUSION

Pretransplant LCM results were not associated with overall graft survival or acute rejection episodes in this study.

Does a positive lymphocyte cross-match contraindicate living-donor liver transplantation?

BACKGROUND

There is still no consensus on the importance of lymphocyte cross-matching (LCM) in the field of living-donor liver transplantation (LDLT).

METHODS

LCM examinations are routinely performed before LDLT, and the results of complement-dependent cytotoxicity were used in this study. A total of 1157 LDLT cases were evaluated. The recipients were divided into four groups based on the LCM and ABO compatibilities: (1) negative LCM and identical/compatible ABO; (2) negative LCM and incompatible ABO; (3) positive LCM and identical/compatible ABO; and (4) positive LCM and incompatible ABO. The diagnosis of antibody-mediated rejection (AMR) was made based on the clinical course, immunological assays and histopathological findings. C4d immunostaining was added if AMR was suspected.

RESULTS

The LCM-positive LDLT recipients showed significantly poorer outcomes than the LCM-negative recipients. Among the LCM-positive recipients, 44.1% of recipients eventually died and 85.2% of recipients revealed positive C4d findings. The survival rate of LCM-positive and ABO-incompatible group was 0.50. The survival days were compared with the LCM-negative and ABO-identical/compatible group, and the LCM-positive and ABO-identical/compatible group clearly showed early death after LDLT, although the ABO-incompatible groups did not show significant. The factors of age, disease, pre-transplant scores, LCM, ABO compatibility and graft-recipient weight ratio showed statistical significance in multivariate analysis for important factors of LDLT outcomes. However, the LCM and ABO compatibilities had no synergetic effects on the LDLT survival.

CONCLUSION

HLA antigens are more widely expressed than ABO antigens, and advanced immunological strategies must be established for LCM-positive LDLT as well as for ABO-incompatible LDLT.