The CD34+cell concentration in peripheral blood predicts CD34+cell yield in the leukapheresis product

Background Measurement of the bem cells collected by leukapheresis has unde rgone marked improvement through the recent advent of CD34 analysis with fl ow cytometry. Methods The relationship between CD34(+) cell count in the peripheral blood (PB) and the leukapheresis product CD34(+) cell yield was examined. One hu ndred patients with hematologic and non-hetamtologic malignancies underwent mobilization, with either growth factors combined with chemotherapy, or gr owth factors alone. Prior to each leukapheresis, PB was obtained for measur ing the WBC, differential and percentsge of CD34(+) cells. The same tests w ere then performed for the corresponding leukapheresis products and the fol lowing correlations quantified: PB to product CD34(+)%, PB to product CD34( +) cell concentration and PB CD34(+) cell concentration, WBC and mononuclea r 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 CD34cell concentration x 10(6)/mL), pi-edicts, with 50% probability, a minimall y acceptable yield of 0.2 x 10(6) CD34(+) cells/kg with a CD34(+) cell conc entration equal to 0.006 CD34(+) cells x 106/mL. A cell concentration of gr eater than or equal to 0.023 CD34(+) cells/mL will ensure that a very, high fraction (> 97%) of the patient population exceeds the minimally-acceptabl e yield. Discussion The CD34(+) cell concentration measured in the PB prior to leuka pheresis 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.