We concur with the comments by Grimaldi and Napoli that the degree of HLA-ABC mismatching will likely have an effect on rejection, sensitization, and graft survival in children. In our study,1 which was limited to a single center, we chose to focus on HLA-DR matching because the current US allocation system gives extra allocation points (in adults) for HLA-DR matching only. The national decision for awarding points for HLA-DR matching alone was based on data demonstrating a significant survival advantage for HLA-DR matching without disadvantaging minorities based on the relatively low frequencies of HLA-ABC matching.2 Indeed, as the data demonstrate in our study,1 the frequency of matching at the DR locus alone is so low that any attempts to match at HLA ABC as part of an allocation system would not be a realistic goal. Because DR matching has previously been shown to be most important in terms of graft survival without disadvantaging minorities, we focused on HLA-DR matching. The current US allocation system would require regional or even national sharing to match children for just HLA DR alone, and attempts at matching at both class I and class II major histocompatibility complex antigens would not be practical, even with broader sharing.
Stock PG. The Effect of HLA-DR Matching on Pediatric Kidney Transplantation—Reply. Arch Surg. 2012;147(1):97-98. doi:10.1001/archsurg.147.1.97-b