Depletion of T-cell receptor alpha/beta and CD 19 positive cells from apheresis products with the CliniMACS device

Background aims. The CliniMACS device (Miltenyi Biotec, Bergisch Gladbach, Germany) was used for depletion of T-cell receptor alpha/beta positive (TCR alpha beta(+)) and CD19 positive (CD19(+)) cells from apheresis products. Methods. Investigators performed 102 separations. Apheresis products with a median 5.8 (minimum to maximum, 1.2-10.4) x 10(10) mononuclear cells were used with a median 358 (92-1432) x 10(6) CD34(+) cells. There were 24.8% (6.1-45.7%) median TCR alpha beta(+) cells and 4.4% (1.2-11.7%) median B cells in the apheresis product. Results. After depletion, a median 0.00097% (0.00025-0.0048%) of TCR alpha beta(+) cells could be detected, and B cells, as determined as CD20(+) cells, were reduced to 0.0072% (0.0008-0.072%). TCR alpha beta(+) cells were depleted by log 4.7 (3.8-5.5), and B cells were depleted by log 4.1 (3.0-4.7). Recovery of mononuclear cells was 55% (33-77%), and recovery of CD34(+) cells was 73% (43-98%). Recovery of CD56(+/)3(-) natural killer cells was 80% (35-142%), recovery of TCR gamma/delta positive (TCR gamma delta(+)) T cells was 83% (39-173%) and recovery of CD14(+) cells was 79% (22-141%). Viability of cells was 98% (93-99%) after separation (all values median). Conclusions. Profound depletion of TCR alpha beta(+) T cells can be achieved with the CliniMACS system. Recovery of CD34(+) stem cells is in the same range than after CD34(+) enrichment and CD3/CD19 depletion. Transplantation with >4 x 10(6) CD34(+) cells/kg can be performed for every patient with 1-5 x 10(4) TCR alpha beta(+) cells/kg and about 5-10 x 10(6) TCR gamma delta(+) cells/kg with two rounds of apheresis.