P042 Accelerated antibody mediated rejection in a heart patient with weak donor specific antibodies present pre-transplant

Abstract We present a case on a 46 year old Caucasian female patient with hypertrophic obstructive cardiomyopathy. The patient’s sensitization history included 3 pregnancies and a flu vaccination 2 months prior to transplant. The pre-transplant single antigen bead assay revealed weak reactivity to the Bw6 epitope including B7 (1,149 MFI) and B8 (775 MFI). The patient received a heart transplant in which B7 and B8 were crossed. As expected, the retrospective flow crossmatch was weakly positive. The patient was treated with Simulect on the day of transplant (Day 0) and with anti-thymoglobulin on Day 3 ( Figure 1A ). On Day 7, the patient went into cardiac arrest and was placed on extracorporeal membrane oxygenation (ECMO). The antibody screen on Day 7 revealed a large increase in donor specific antibodies (DSA) to B7 (21,694 MFI) and B8 (21,460 MFI). Positive ERG, CD68, and C4d staining on the Day 7 biopsy corroborated antibody mediated rejection (AMR). The patient was treated with plasma exchange, IVIG, Rituxan, and Cytoxan. At Day 14, ECMO was discontinued. DSAs declined to levels observed at pre-transplant ( Figure 1B ). Although antibody and biopsy results demonstrated a reduction in AMR, the patient became neutropenic and developed fever, bacteremia, a necrotic leg wound, and a fungal infection in the brain. She progressed to brain death. This case describes an amnestic response to weak DSA which contributed to cardiac arrest. Augmented immunosuppression used to treat an anamnestic AMR is associated with a significant risk of fatal infectious complications.