Isolation of CD34+progenitor cells from peripheral blood by use of an automated immunomagnetic selection system: factors affecting the results

BACKGROUND: The isolation of CD34+ cells from mobilized peripheral blood is being increasingly used in the setting of allogeneic or autologous hematop oietic cell transplantation. Investigation of variables that may influence the effectiveness of CD34+ cell selection is of interest. STUDY DESIGN AND METHODS: Fifty-one CD34+ cell selections from peripheral b lood progenitor cells (PBPCs) (39 allogeneic and 12 autologous) were perfor med using a magnetic cell separator (Isolex 300i, Baxter), including versio n 2.0 software. The results obtained were analyzed for different processing variables. The feasibility of transplanting these isolated CD34+ cells was also analyzed. RESULTS: The isolated CD34+ cell fraction had a median purity of 88.9 perce nt (range, 47.8-98.3). The median recovery of CD34+ cells was 45.1 percent( 13.8-76.2), and the median colony-forming unit- granulocyte-macrophage (CFU -GM) content was 17.2 percent (0.8-58.6). Logarithms of T- and B-cell deple tion had median values of 3.7 and 2.8, respectively. The version 2.0 softwa re of the Isolex 300i gave a higher CD34+ cell recovery in the enriched cel l fraction (median 57.8%) than did version 1.11 (39.4%) or 1.12(44.4%) (p = 0.01). The use of recombinant human deoxyribonuclease I during cell proces sing yielded more CD34+ cells (53% vs. 41%, p = 0.01) and higher purity (92 .8% vs. 87%, p = 0.03). There was a cor relation between the percentage of CD34+ cells labeled with the monoclonal antibody 8G12 clone and the percent age of CD34+ cells labeled with the monoclonal antibody used during the pro cessing technique (9C5 clone) in the initial, enriched, and depleted CD34cell fractions (R-2 = 0.95; 0.92; 0.78, p< 0.005, respectively). Median tim es for recovering >0.5 x 10(9) per L of granulocytes and >20 x 10(9) per L of platelets were 13 and 16 days in the allograft patients and 13 and 14 da ys in the autograft patients. CONCLUSION: CD34+ cells can be highly and effectively isolated from allogen eic and autologous grafts by use of this automated technique, with a high g rade of T- and B-cell depletion. These purified CD34+ cell components can e ngraft normally.