Comparison of HISTO SPOT HLA AB With Cross-Match Results

Single antigen bead assays have revolutionised the identification and definition of HLA-specific antibodies and HLA-specific antibody profiles present in patients awaiting transplantation are routinely characterised to inform organ allocation. For highly sensitised patients with a lower likelihood of finding a compatible donor, de-listing of unacceptable antigens is an option to release organ offers. In this study, 164 serum samples from 106 potential renal transplant recipients were tested using HISTO SPOT HLA AB in parallel with testing by LABScreen Single Antigen (One Lambda) and cross-matching by both CDC and flow cytometry. The results were analysed to assess the ability of HISTO SPOT HLA AB to predict a cross-match result and to understand the relative sensitivity of this test compared with other available assays. 136 samples analysed were positive for donor-specific antibodies (DSAs) using HISTO SPOT HLA AB. Of these, 17 (12.5%) were CDC positive, and 82 (60.3%) were positive by flow cytometry. A total of 28 sera which were negative for DSAs using HISTO SPOT HLA AB were negative by CDC and 25 (89.3%) were also flow cytometry cross-match negative. In this early study, HISTO SPOT HLA AB has a 100% negative predictive value for CDC and 89.3% for flow cytometry cross-matching. HISTO SPOT may therefore prove a useful additional tool to inform de-listing strategies and to facilitate transplantation in highly sensitised patients.