An in Vitro Comparison of Intra-Operative Isohemagglutinin and Human Leukocyte Antigen Removal Techniques in Pediatric Heart Transplant

Background: Highly sensitized pediatric patients awaiting heart transplantation experience longer wait times and higher waitlist mortality. To improve the likelihood of successful transplantation, various strategies have been utilized, including peri-operative plasmapheresis, to broaden potential donor pools. Methods: This in vitro study utilized two membrane-based plasmapheresis (MP, Prismaflex) and two centrifuge-based plasmapheresis (CP, Spectra Optia, Terumo BCT) circuits incorporated into four separate extracorporeal (EC) circuits primed with high titer, highly sensitized type O donor whole blood. Assays were performed to determine baseline anti-A and B isohemagglutinin titers (IT) and anti-human leukocyte antigen (HLA) antibodies and then at 30-minute increments until completion of the run at two hours. Results:  There was a decrease in anti-A and anti-B IgM and IgG titers with both MP and CP.  Mean anti-A and anti-B titer reduction was by 4.625 titers (93.7% change) and 4.375 titers (93.8% change) using MP and CP, respectively.  At two hours of apheresis, CP reduced mean fluorescence intensity (MFI) by 2-3.5 fold and MP reduced MFI by 1.7-2.5 fold. Conclusions: In this in vitro plasmapheresis model of IT and anti-HLA antibody reduction, both MP and CP can be used quickly and effectively to reduce circulating antibodies, and CP may have some greater degree of efficiency. Further in vivo research on incorporating CP or MP into EC circuits at the time of transplant is needed. However, with further clinical research, there is potential to broaden potential donors and improve patient safety in sensistized patients.