Abstract 2962: Donor-specific Antibodies Correlate with Events in Heart Transplant Patients

Abstract

Antibodies (ab) against human leukocyte antigens (HLA) in transplant (tx) recipients are associated with poor outcome. Flow PRA (panel reactive ab) detects non-specific ab against Class I & II HLA (%). New technology detects ab against donor HLA = Donor-Specific Ab (DSA). Experience with DSA in heart tx patients (pts) is limited. Purpose: To evaluate presence of non-specific ab & DSA and to correlate it with events in heart tx pts. Methods : We included all pts with heart tx done Feb 1986-Feb 2008 followed at our ctr with post-tx flow PRA drawn March 2006-Feb 2008 on random sample or event-related sample, ordered at clinician’s discretion. Random sample was drawn during clinic visit or hospital admission not related to graft rejection. Event is defined as hospital admission for suspected graft rejection. There were 277 samples drawn for flow PRA from 93 pts. To reduce bias related to multiple samples from 1 pt we included only 1 sample with highest PRA %. Pts were categorized in 2 groups: PRA ≥ 10% (high) and PRA < 10% (low). Low titer DSA was < 100,000 molecules of equivalent soluble fluorescence units (MESF). Results : Among 93 pts, 27 pts had PRA ≥10% (29%), among which 13 pts had event (14% of 93 pts) and 66 pts had PRA < 10% (71%) among which 3 pts had event (3% of 93 pts). Low PRA Group: Among 66 pts with PRA < 10%, 63 pts had no events (95.5%). Among 66 pts with PRA < 10%, 42 pts had no DSA tested and 24 pts had DSA tested. Among 24 pts with DSA tested, 23 pts had negative DSA and 1 pt had positive low titer DSA (this pt had no event). Three pts with negative DSA had an event; one of them had cross-reactive ab. High PRA Group: 27 pts with PRA≥10% were subcategorized in 2 groups based on the presence or the absence of the event. Group 1(N = 14 (52%)) had no event:8 pts did not have DSA drawn, 5 pts were DSA negative and 1 pt was positive with low titer DSA. Group 2(N = 13 (48%)) had an event:10 pts were DSA positive with high-titer, whereas 3 pts were DSA negative (1 pt had cross-reactive ab to donor-specific antigen). Difference between Groups 1 and 2 was significant by Fisher’s exact test (p < 0.05). Conclusions : Majority of pts hospitalized for suspected rejection (75%) had high-titer positive DSA (62.5%) or cross-reactive ab to donor-specific antigen (12.5%). This study will be basis for future prospective DSA monitoring.