Presence of Promyelocytes in Peripheral Blood as a Novel Predictor of Optimal Timing for Single-Step Peripheral Blood Stem Cell Collection

Abstract

Background: Peripheral blood stem cell (PBSC) collection places a burden on the patient and ideally should be completed in a single procedure. Consequently, a convenient predictive factor is needed for clinical use. Methods: This retrospective study included 72 patients who underwent autologous PBSC collection. A median volume of 3.9×10 6 CD34-positive cells/kg (range: 0.3-47.4×10 6 cells/kg) was collected on the first day. We defined failure as an inability to collect 2.0×10 6 cells/kg on the first day. Patients were classified into failure (n = 25, 34.7%) and success groups (n = 47, 65.3%), and their clinical backgrounds were analyzed. Results: The success group included a significantly larger number of cases in which a differential white blood cell count of the peripheral blood on the day of PBSC collection detected promyelocytes (n = 34, 72.3% vs. failure group: n = 11, 44.0%; P＝0.008). Sixty-two patients underwent autologous PBSC transplantation with a median of 5.6×10 6 transplanted cells/μL (range: 1.60-47.4×10 6 cells/µL). Among transplanted patients, no significant differences were observed between the success and failure groups in terms of the intervals until neutrophil, platelet, and red blood cell engraftment. Conclusion: The presence of promyelocytes in peripheral blood may be a useful indicator of the optimal timing for single-step PBSC collection.