Immunomagnetic selection of CD34+ cells: factors influencing component purity and yield

BACKGROUND: In immunomagnetic selection of CD34+ cells from HPC transplants, not all factors that affect yield and purity of CD34+ cells are known. METHODS: Forty-three consecutive procedures of immunomagnetic selection of CD34+ cells from peripheral blood HPCs and bone marrow harvests (autologous harvests, n = 27; allogeneic harvests; n=16) were performed by use of a cell selection system (Isolex 300i, Baxter Immunotherapy). The composition of the starting component and the subsets of CD34+ cells were analyzed for correlation with the yield and purity of the final component. RESULTS: The mean purity of the final components was 84.3 percent (range, 27-99%), and the mean yield was 51.4 percent (range, 9.4-80. 4%). Partial regression analysis showed that, among the factors correlating with purity and/or yield, the RBC volume in the starting fraction had the highest predictive impact on the purity and yield of CD34+ cells, even after the exclusion of procedures using bone marrow harvests as an HPC source (beta coefficient, -0.704; p = 0. 001). CONCLUSION: The use of the Isolex 300i system allows efficient recovery of CD34+ cells in routine selection procedures. The volume of RBCs in the starting component should be minimized to ensure a high yield and purity of the final component.