Liver transplant recipients weaned off immunosuppression lack circulating donor-specific antibodies

Human leukocyte antigen (HLA)-specific antibodies (Abs) were examined in 73 clinically stable liver transplant recipients divided into group A (n = 19; clinically tolerant), group B (n = 34; undergoing weaning, on minimal immunosuppression), and group C (n = 20; had failed drug withdrawal or weaning never attempted). Of 19 patients in group A, six (32%) had anti-HLA Abs; none were donor-specific. In contrast, 23 of 34 patients (67%) in group B and nine of 20 patients (45%) in group C exhibited anti-HLA Abs (p = 0.02). Furthermore, 15 of 19 patients in groups B and C (9/12, p = 0.01 and 6/7, p = 0.01, respectively) exhibited donor-specific anti-HLA Abs. The prevalence of donor-specific HLA Abs was significantly higher in nontolerant patients. Five years after initial evaluation, >90% (18/19) group A patients remained off immunosuppression. One of seven of these patients available for retesting exhibited donor-specific Abs. In group B, two-fourths of 34 patients (12%) weaned successfully were HLA-Ab negative; four patients who experienced rejection while undergoing weaning exhibited anti-HLA Ab initially and at 5 years. Thus, most of the liver recipients off immunosuppression lacked donor-specific alloAbs. The occurrence of these alloAbs should now be examined prospectively in a drug weaning trial.