Background. Single antigen bead testing is currently accepted as standard practice for evaluating HLA alloantibodies. However, it is well established that the expression of HLA antigens, on beads, is not representative of actual cellular expression. It is well recognized that the cellular surface expression of certain HLA loci are expressed at relatively low levels. As such, single antigen bead data may overrepresent the impact of HLA antibodies for certain loci. Importantly, for clinical assessments, the cell surface expression of target donor HLA antigens is not routinely considered unless it is a known null allele. Methods. Using a panel of variably reactive DQ4 allosera, we have evaluated DQ4 antigen assembly and surface expression on cell lines and in transfectants carrying DQ4 variants. Results. A single amino acid change at residue 137 in the α2 domain of the DQα chain can significantly affect the stability of the αβ heterodimer and result in the reduced surface expression of the affected DQ antigens, resulting in changes in anti-HLA antibody reactivity. Conclusions. A single amino acid residue in the DQα chain can influence the expression of a DQ4 molecule. Importantly, such surface expression variability does significantly impact allo-antibody reactivity. As a result, amino acid sequence variations in the α2 and β2 domains of the HLA class II serological groups and alleles within serological groups should be further investigated to understand the scope of allelic expression variability. Identifying low surface expressing HLA antigens/alleles might facilitate the understanding of certain discordant clinical observations.
Background. Normothermic machine perfusion (NMP) promises to catalyze organ preservation, therapeutic discovery, and disease modeling. Commercial organ perfusion devices remain inaccessible for research because of restricted access, high costs, and steep technical learning curves. Methods. To overcome these barriers, an NMP circuit was developed using recycled, repurposed, and low-cost components. Porcine kidneys and autologous blood were used for iterative optimization. A porcine kidney autotransplantation protocol was adapted to evaluate in vivo kidney function after NMP. Nontransplantable human donor kidney, spleen, and pancreas specimens were perfused using human blood products. Results. This effort resulted in an ultra-low-cost (~$2000) NMP system capable of perfusing porcine kidneys and human organs (kidney, pancreas, and spleen) for up to 24 h with evidence of both function and viability. Key innovations included a mechanism to permit low-flow perfusion in nonheparinized organs and a containment bag with adjustable magnets to provide stabilization. Porcine kidneys perfused on this platform demonstrated in vivo function upon autotransplantation with survival for 30 d. Conclusions. We conclude that an ultra-low-cost NMP platform can be constructed from readily available materials. This financially sustainable and scalable model provides a road map to advance ex vivo discovery.
Background. To increase organ availability in areas with low transplant access, the use of deceased donors infected with Trypanosoma cruzi for liver and kidney transplantation has been adopted, balancing the risk of transmission. This Argentinean study aimed to analyze the reactivation rate and safety of this practice. Methods. This study combined 2 complementary approaches: a cross-sectional analysis of the Argentinean Transplant Registry (2006–2020) and a retrospective multicenter cohort study of solid organ transplant recipients. The cohort study was designed to assess the risk of donor-derived T. cruzi infection in liver and kidney transplant recipients across Argentina. Results. The cross-sectional analysis identified a seroprevalence of 3.52% (528/14 966) among deceased donors. Data were obtained from 129 recipients who received an organ from a T. cruzi -positive donor. With a median follow-up of 3.62 y, and high adherence to surveillance (83%), T. cruzi infection was diagnosed in 22% of recipients, with a median time of 57.5 d posttransplant. Seventy-five percent (n=21/28) of the patients remained asymptomatic. Neither prior T. cruzi seropositivity in the recipient (odds ratio, 0.27; 95% confidence interval, 0.01-4.89; P = 0.200) nor a history of rejection (odds ratio, 0.63; 95% confidence interval, 0.19-2.12; P = 0.452) was significantly associated with Chagas reactivation. Almost all infected patients received benznidazole, and the infection resolved without sequelae in those treated. The treatment was well tolerated. Chagas disease was never identified as the cause of death. Conclusions. The use of T. cruzi -positive donors for liver and kidney transplantation is safe, but requires careful monitoring, especially during the first year posttransplant.
