HLA class I DNA typing of 215 ''HLA-A, -B, -DR zero mismatched'' kidney transplants

DNA typing for HLA class II improves the typing quality and this was shown previously to be relevant for kidney graft survival. In this project we addressed the question whether molecular typing for HLA class I also increases the efficacy of HLA matching in kidney transplantation. 215 HLA-A,-B,-DR zero-mismatched donor/recipient pairs as defined by serological typing were selected. Retrospective HLA-A and HLA-B typing was performed both by the PCR-SSP and the PCR-SSOP method. DNA typing for HLA-A revealed discrepant results to serology in 5.7% of the donors and 2.8% of the recipients. HLA-B typing discrepancies were found in 6.6% of the donors and 5.6% of the recipients. 10.4% of the donors and 6.5% of the recipients showed either an HLA-A or an HLA-B discrepancy. Nearly one-third of the HLA-A discrepancies affected A19 splits. The most common reason for HLA-A discrepancies was the erroneous assignment of serological blanks, whereas HLA-B errors were caused mainly by the assignment of incorrect specificities. DNA typing allowed the definition of KLA-A and -B split specificities in all 118 ''splitable'' cases for which only broad specificities were reported based on serological typing. A total of 183 DNA class I compatible transplants had a 15% higher one-year graft survival rate than 32 transplants for which DNA typing revealed a class I incompatibility.