BACKGROUND: Measurement of the stem cells collected by leukapheresis has undergone marked improvement through the recent advent of CD34 analysis with flow cytometry. METHODS: The relationship between CD34+ cell count in the peripheral blood (PB) and the leukapheresis product CD34+ cell yield was examined. One hundred patients with hematologic and non-hematologic malignancies underwent mobilization, with either growth factors combined with chemotherapy, or growth factors alone. Prior to each leukapheresis, PB was obtained for measuring the WBC, differential and percentage of CD34+ cells. The same tests were then performed for the corresponding leukapheresis products and the following correlations quantified: PB to product CD34+%, PB to product CD34+ cell concentration and PB CD34+ cell concentration, WBC and mononuclear cell (MNC) concentration to product CD34+ cell yield/kg. RESULTS: The best predictor of product yield of CD34+ cells/kg x 10(6) was the PB CD34+ cell concentration with r = 0.93. The resulting regression formula (on log-log scale), log10 yield/kg = 1.52 + (0.99 x log10 PB CD34+ cell concentration x 10(6)/mL), predicts, with 50% probability, a minimally acceptable yield of 0.2 x 10(6) CD34+ cells/kg with a CD34+ cell concentration equal to 0.006 CD34+ cells x 10(6)/mL. A cell concentration of > or = 0.023 CD34+ cells/mL will ensure that a very high fraction (> 97%) of the patient population exceeds the minimally-acceptable yield. DISCUSSION: The CD34+ cell concentration measured in the PB prior to leukapheresis is an excellent predictor of the yield of CD34+ cells generated in the PB stem cell product and should be used to signal the initiation of leukapheresis for post-mobilized patients.
BACKGROUND: Measurement of the stem cells collected by leukapheresis has undergone marked improvement through the recent advent of CD34 analysis with flow cytometry. METHODS: The relationship between CD34+ cell count in the peripheral blood (PB) and the leukapheresis product CD34+ cell yield was examined. One hundred patients with hematologic and non-hematologic malignancies underwent mobilization, with either growth factors combined with chemotherapy, or growth factors alone. Prior to each leukapheresis, PB was obtained for measuring the WBC, differential and percentage of CD34+ cells. The same tests were then performed for the corresponding leukapheresis products and the following correlations quantified: PB to product CD34+%, PB to product CD34+ cell concentration and PB CD34+ cell concentration, WBC and mononuclear cell (MNC) concentration to product CD34+ cell yield/kg. RESULTS: The best predictor of product yield of CD34+ cells/kg x 10(6) was the PB CD34+ cell concentration with r = 0.93. The resulting regression formula (on log-log scale), log10 yield/kg = 1.52 + (0.99 x log10 PB CD34+ cell concentration x 10(6)/mL), predicts, with 50% probability, a minimally acceptable yield of 0.2 x 10(6) CD34+ cells/kg with a CD34+ cell concentration equal to 0.006 CD34+ cells x 10(6)/mL. A cell concentration of > or = 0.023 CD34+ cells/mL will ensure that a very high fraction (> 97%) of the patient population exceeds the minimally-acceptable yield. DISCUSSION: The CD34+ cell concentration measured in the PB prior to leukapheresis is an excellent predictor of the yield of CD34+ cells generated in the PB stem cell product and should be used to signal the initiation of leukapheresis for post-mobilized patients.