Time of detection of APB. Fifty-five of 550 patients had APB detected on serum IFE. The percentage of patients who had APB detected before the first transplant (PRE–Tx-1) (n = 55), after the first transplant (POST–Tx-1) (n = 55), and after the second transplant (POST–Tx-2) (n = 45) is shown. Twenty-eight patients had APB in more than one interval. Forty-eight patients had OB; of these, 24 (50%) had OB detected in more than one interval, 2 patients (4%) before and after the first transplant, 3 patients (6%) before and after the first transplant and after the second transplant, and 19 patients (40%) after both first and second transplants. Twenty-three patients had apparent IS; of these five (22%) had IS detected in more than one interval (one patient had both OB and IS in more than one interval). Two patients (9%) had IS before the first transplant and after the second transplant and three patients (13%) after both first and second transplant.