FACTORS INFLUENCING THE TIMING OF PERIPHERAL-BLOOD STEM-CELL COLLECTION (PBSC)

High-dose conditioning regimens followed by autologous peripheral bloo d stem cell rescue are frequently used for the treatment of solid tumo rs and hematological malignancies. In 24 patients up to four periphera l stem cell collections (PBSC) were performed after priming with vario us chemotherapies and G-CSF (300 mu g s.c, per day). In 16 patients (g roup A) more than 2x10(6) CD 34 positive cells per kg bodyweight could be collected; fewer were harvested in the remaining eight patients (g roup B). The amount of collected CD 34 positive cells correlated with the median number of these cells in the peripheral blood at the start of PBSC. The two groups differed both in recovery time after priming-i nduced cytopenia (4 vs 6 days from nadir) and in the number of WBC (21 x 10(6) mL(-1) vs 6.1x10(6) mL(-1)) and platelets (133x10(6) mL(-1) v s 58x10(6) mL(-1)) reached at first day of PBSC. No difference between the two groups was seen according to age, duration of disease or dise ase status. However, the intensity of prior treatment was significantl y greater in group B than in group A. These observations indicate that the toxicity of previous chemotherapy is the most important factor fo r the mobilization of sufficient CD 34 positive cells into the periphe ral blood. (C) 1997 Elsevier Science Ltd.