Impact of leukapheresis cell composition on immunomagnetic cell selection with the Baxter Isolex 300i device: a...

Immunomagnetic cell selection (ICS) of CD34(+) cells is increasingly adopted in allogeneic and autologous transplant settings. Because many variables can affect the final results of ICS, we focused our study toward the influence exerted by the leukapheresis (LKF) cell composition on recovery, purity, and log of T and B depletion of the immunoselected cells. A total of 39 consecutive CD34(+) ICS were performed with the Isolex 300i (Baxter) device on 39 LKF from 9 HLA haploidentical donors and 20 patients. Flow cytometric analysis was performed both on the leukapheresis content and on the immunoselected cells. The statistical analysis was performed utilizing the Pearson's correlation test and the Mann-Whitney U test. The median purity and recovery of the immunoselected CD34(+) cells were 95.3% (IR: 93.0-99.0) and 55.1% (IR: 41.8-68.2), respectively. The median log of T and B depletion were 3.87 (IR: 3.5-4.3) and 2.9 (IR: 2.5-3.5), respectively. Our data indicate that not only the CD34(+) cell load but also the ratio among the cells belonging to the starting fraction can influence the results of ICS. LKF collection protocols have to be addressed to collect an high number of CD34(+) cells (>500 x 10(6)) without taking care of the contaminating cells when the Baxter Isolex 300i device is employed.