Characterization of the humoral immune response in two paediatric patients transplanted with split livers from ABO‐incompatible living‐related donors: appearance of cytomegalovirus‐induced ABO antibodies

Two blood group O paediatric patients, 12 and 6 months old, were transplanted with liver segments from their blood group A2Le (a–b+) Se and blood group A1Le (a–b+) Se fathers, respectively. Recipient anti‐A antibody titres were reduced prior to transplantation by blood exchange. Both patients had rejection episodes in the post‐transplant period that were reversed by anti‐rejection therapy. No anti‐A antibody titre rise occurred concomitant with these rejections. Postoperatively both patients had cytomegalovirus (CMV) infections, and simultaneous with these infections, a strong increase in anti‐A antibody titres was seen, but no rejection occurred. The anti‐A antibody titre increase seemed to be specific for A antigens, because the anti‐B and anti‐αGal (anti‐pig) antibody titres did not show any changes. CMV infection is a serious cause of morbidity and mortality in immunosuppressed patients, and the virus can influence glycosylation of infected cells. Whether this can explain the importance of the infection in relation to the increase in titre remains to be elucidated.