Unintended Consequences of the New National Kidney Allocation Policy in the United States

available at http://www.ncbi.nlm.nih.gov/pubmed/26137963 Editorial Comment: The new kidney allocation system that was activated last year increases the opportunity for transplantation in those with the highest levels of antibody sensitization. Specifically those candidates with panel reactive antibody levels of 98% to 100% will have the greatest increase in opportunity. This system is predicated on tissue typing that assesses the HLA-A, B, DR and DQ loci. It has become apparent that other loci, notably the DP locus, are important targets for antibodies, especially in highly sensitized candidates. The new system shares well matched kidneys across broader geographic areas, so it is important that cross-match predictions are accurate. This system will ensure that the matched kidney is transplanted into the intended candidate. Reassigning a new recipient after a positive cross-match will lead to increased ischemic times and possible discard. The authors describe the importance of characterizing the DP locus. Overall 11% of positive cross-matches in a test cohort were positive only due to HLA-DP antibodies. In their experience 6% of HLA-A, B and DR zero mismatches had a positive cross-match due to HLA-DP directed antibodies. This article is a plea for universal reporting of more complete HLA antibody testing so that virtual cross-match prediction can be more accurate.