P162 Unexpected positive flow crossmatch with a deceased donor organ: Timing of autologous flow crossmatch?

Abstract

We describe two recipients of deceased donor organs who had a positive flow crossmatch despite being negative for donor specific antibodies (DSA), as determined by single antigen beads (SAB; LabScreen, One Lambda). The first patient, a 56 year old male, was offered a kidney from a deceased donor. The positive allogeneic flow crossmatch results are shown in Table 1. Interestingly, a recent SAB was negative for DSA. To facilitate clinical interpretation, an autologous flow crossmatch was immediately performed, which demonstrated significant auto-reactivity. Therefore, the positive allogeneic flow crossmatch was interpreted as most likely due to auto-reactive antibodies and the medical decision was to proceed with transplantation. The second patient, a 60 year old female, was offered a kidney from a deceased donor. The positive allogeneic flow crossmatch results are shown in Table 1. A recent SAB was negative for any antibodies greater than mean fluorescence intensity of 300. An autologous flow crossmatch was immediately performed, which demonstrated significant, although somewhat attenuated, auto-reactivity. Concerned that auto-antibodies didn’t explain all the reactivity seen, an additional two random donors were flow crossmatched using this recipient’s serum and identified similar B-cell reactivity. Ultimately the medical decision was to proceed with transplantation. In conclusion, an autologous flow crossmatch is our first step to evaluate an unexpected positive allogeneic flow crossmatch. As illustrated in our second patient, the results of the autologous flow crossmatch may require further testing to fully explain results and make the best possible transplant decision. We have modified our protocol to perform an upfront autologous flow crossmatch for potential recipients of deceased donor organs. This practice change has decreased turn-around-time and improved communication with surgical colleagues. Download : Download high-res image (38KB) Download : Download full-size image