Serial measurement of Flt3L after hematopoietic stem cell transplantation. (A) Serial serum Flt3L measurements in patients with non-APL AML undergoing hematopoietic stem cell transplantation remaining in continuous remission (n = 8; open circles and broken lines; shaded region indicates normal range). Patients were sampled prior to conditioning (day −7), on the day of transplant (day 0), and on days and months posttransplant, as indicated. Patients were selected over the same period as panel B. (B) Serial serum Flt3L measurements in 7 patients with non-APL AML undergoing hematopoietic stem cell transplantation who relapsed (n = 7; filled circles and broken lines). Consecutive relapsed patients ≤2 years posttransplant are reported. (C) Interval between drop in Flt3L below the normal range and diagnosis of relapse. Summary of calendar-driven Flt3L measurement in 17 patients indicating timing of the point at which Flt3L first went below normal relative to the hematological diagnosis of relapse. Includes all patients in B with 10 additional patients in whom ≥1 Flt3L measurement was recording posttransplantation.