DETECTION OF ANTI-HLA ANTIBODY BY FLOW CYTOMETRY IN PATIENTS WITH A LEFT VENTRICULAR ASSIST DEVICE IS ASSOCIATED WITH EARLY REJECTION FOLLOWING HEART TRANSPLANTATION

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Abstract
Patients with a left ventricular assist device (LVAD) as a bridge to heart transplantation (HT) often have elevated levels of panel reactive antibodies (PRA).The clinical significance of anti-human histocompatibility leukocyte antigen (HLA) antibodies detected by flow cytometry in PRA negative patients remains unclear. Eighteen patients who underwent LVAD placement as a successful bridge to HT had standard anti-human globulin complement-dependent cytotoxicity and retrospective flow cytometry assays performed to detect class I anti-HLA antibodies. A positive flow result was defined as a fluorescent ratio of ≥3:1 versus a negative control. Six patients had anti-HLA antibodies detected by flow cytometry. Univariate analysis demonstrated more moderate-severe rejection episodes (ISHLT ≥ IIIA) at 2 months (0.83±0.75 vs. 0;P =0.04) and a trend toward decreased time to first rejection (61±17 vs. 225±62 days;P =0.06) in these patients. No differences were observed in donor-recipient HLA mismatch or 1 year Kaplan-Meier survival between patients with or without anti-HLA antibodies. Despite a negative PRA, LVAD patients with class I anti-HLA antibodies detected by flow cytometry have a greater incidence of moderate-severe rejection in the first 2 months after HT. Flow cytometry may be a useful clinical tool in screening PRA negative LVAD patients before transplantation. Patients with positive anti-HLA antibody screening by flow cytometry may require more intensive immunosuppression in the early post-HT period.