Anti-B-mediated rejection of an ABO-incompatible cardiac allograft despite aggressive plasma exchange transfusion.

A group A recipient received a group B cardiac allograft. Aggressive plasma exchange with replacement by group AB FFP initially reduced the recipient's anti-B titer to a low level. Once a secondary anti-B response was mounted, plasma exchange was ineffective and IgM and IgG anti-B titers rose to high levels. Associated with the increased anti-B titers, cardiac function deteriorated and on day 13 the group B heart was replaced by a group A allograft. The compatible allograft functioned well initially but was eventually rejected, and the patient died 51 days after the initial transplantation. Histologic examination of the first allograft revealed a delayed form of typical antibody-mediated rejection with destruction of the microvasculature associated with antibody deposition and acute inflammation. By contrast, the histopathology of the second compatible allograft was typical of cell-mediated allograft rejection. Extracts of myocardium from the incompatible heart contained IgM and IgG anti-B, while no anti-B alloantibody was demonstrable in the extracts of the ABO-compatible allograft and a control heart. The utility of plasma exchange with group AB FFP replacement in such a circumstance requires further study.