The HLA-matching Effect in Different Cohorts of Kidney Transplant Recipients: 10 Years Later.

Sasaki N, Idica A.

Clinical Transplants 2010, Chapter 25

Abstract

Almost all the HLA-matching effects found by the 2000 analysis were confirmed by this study. The only HLA-matching effect found in the 2000 analysis that disappeared were those of "small matching effect" found in sub-populations of type I diabetes (PRA < 10% donor age 20-35). The 2000 analysis found a lack of HLA matching effect in non-African American kidney transplant patients with type I diabetes between 1987 and 2000. The 2000 analysis found that a patients' ethnic group was a factor in graft survival; African American patients were found to have a significantly lower 10-year graft survival in the 5 or 6 mismatched group (27%) compared to Caucasian patients (40%). In addition Asian patients (42%) had higher graft survival compared to that of Caucasian patients. In this study we observe a similar pattern with death-censored graft analysis for all ethnic groups with 10-year graft survivals at 72.9% for Asians 69.5% for Caucasians and 49.3% for African Americans. There was an overall lack of HLA-matching effect on patient survival in the 2000 analysis. In our current analysis the patient survivals remained virtually the same despite moderate increase in graft survival over the same period of time. The HLA-C locus mismatch was found to have additive effect to the 10-year graft survival trends observed in A and B mismatch cases. HLA-DQ mismatch on the other hand showed limited HLA-matching effect and did not show the same additive effect as C. There are various possible issues in the DQ mismatch analysis from the consistency of DQ typing results lack of diversity in the DQ antigen to the possibility of DQ mismatch having little effect on the graft survival. Utilizing kidney transplant cases performed from 1995 through 2000 the 2000 analysis projected 10-year survivals of 64% and 47% for the 0 ABDR mismatch and 5 or 6 ABDR mismatched cases respectively; the 2000 projection only missed actual death-censored survivals by 9% lower for the 0 mismatch and 17% lower for the 5 or 6 mismatch cases. Utilizing the transplant cases of 2005 through 2009 we projected their 10-year graft survivals for year 2020. The 10-year graft survival for 0 ABDR mismatched patients is expected to be over 85% and nearly 70% for 5 or 6 ABDR mismatched patients. The general upward trend of graft survival we have observed in the last 10 years has been dependent upon the development of novel transplant protocols and use of novel immunomodulatory reagents. This trend is likely to continue given the promise of new drugs and personalized healthcare. The decreasing range of the differences in the 10-year graft survival between best matched and worst matched HLA groups is also likely to continue. One interesting trend that is clearly evident is the increasing difference between the best and worst HLA-matching in terms of the associated graft half-life. The positive HLA-matching effect on long-term graft survival is clearly evident and should be taken into consideration for all kidney transplants."