Complement-activating donor-specific anti-HLA antibodies and solid organ transplant survival: A systematic review and meta-analysis

Background Anti-human leukocyte antigen donor-specific antibodies (anti-HLA DSAs) are recognized as a major barrier to patients’ access to organ transplantation and the major cause of graft failure. The capacity of circulating anti-HLA DSAs to activate complement has been suggested as a potential biomarker for optimizing graft allocation and improving the rate of successful transplantations. Methods and findings To address the clinical relevance of complement-activating anti-HLA DSAs across all solid organ transplant patients, we performed a meta-analysis of their association with transplant outcome through a systematic review, from inception to January 31, 2018. The primary outcome was allograft loss, and the secondary outcome was allograft rejection. A comprehensive search strategy was conducted through several databases (Medline, Embase, Cochrane, and Scopus). A total of 5,861 eligible citations were identified. A total of 37 studies were included in the meta-analysis. Studies reported on 7,936 patients, including kidney (n = 5,991), liver (n = 1,459), heart (n = 370), and lung recipients (n = 116). Solid organ transplant recipients with circulating complement-activating anti-HLA DSAs experienced an increased risk of allograft loss (pooled HR 3.09; 95% CI 2.55–3.74, P = 0.001; I2 = 29.3%), and allograft rejection (pooled HR 3.75; 95% CI: 2.05–6.87, P = 0.001; I2 = 69.8%) compared to patients without complement-activating anti-HLA DSAs. The association between circulating complement-activating anti-HLA DSAs and allograft failure was consistent across all subgroups and sensitivity analyses. Limitations of the study are the observational and retrospective design of almost all included studies, the higher proportion of kidney recipients compared to other solid organ transplant recipients, and the inclusion of fewer studies investigating allograft rejection. Conclusions In this study, we found that circulating complement-activating anti-HLA DSAs had a significant deleterious impact on solid organ transplant survival and risk of rejection. The detection of complement-activating anti-HLA DSAs may add value at an individual patient level for noninvasive biomarker-guided risk stratification. Trial registration National Clinical Trial protocol ID: NCT03438058.
In a systematic review and meta-analysis, Alexandre Loupy and colleagues study antibody biomarkers of solid organ transplantation outcomes.
Author summary Why was this study done? Allograft rejection is a major threat to allografts, with consequences for the patients in terms of mortality and morbidity. Over the last decade, studies on solid organ transplant patients have reported that complement-activating anti-human leukocyte antigen donor-specific antibodies (anti-HLA DSAs) are highly associated with allograft rejection and failure, with varying magnitudes of effect. What did the researchers do and find? This study was designed to evaluate the clinical relevance of complement-activating anti-HLA DSAs at a population level and across the entire solid organ transplants spectrum (kidney, liver, heart, and lung transplant patients). The present meta-analysis, including 37 studies and 7,936 patients, provides evidence that circulating complement-activating anti-HLA DSAs are a major determinant of long-term allograft rejection and allograft failure. What do these findings mean? These results suggest that circulating complement-activating anti-HLA DSAs are potential noninvasive biomarkers to stratify the risk for allograft failure and rejection. Further research will be needed to investigate the possibility that the detection of these antibodies might have therapeutic significance and could provide opportunities for a pathogenesis-driven approach to prevention and/or treatment of rejection for solid organ transplant recipients.