A one-step large-scale method for T- and B-cell depletion of mobilized PBSC for allogeneic transplantation

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Abstract
The presence of Tand B cells in allogeneic grafts contributes to GvHD and to EBV-associated lymphoproliferative disease (LPD). Depletion of T and B cells from the graft decreases the risk of these complications. T and B cells were depleted from mobilized peripheral stem cells from volunteer donors (n = 5) using anti-CD3 and anti-CD19 Abs conjugated to magnetic microbeads, and the CliniMACS device. The function of the stem cells after depletion was evaluated using colony assays and non-obese diabetic (NOD)/SCID repopulating experiments. The mean mononuclear cell (MNC) count prior to T- and B-cell depletion was 2.19 × 1010 (range 1.48–3.53). After depletion, the mean percentage of contaminating T cells was 0.02% (range 0.01–0.04%) with a mean log10 depletion of 3.4 (range 3–3.8). The mean percentage of contaminating B cells was 0.1% (range 0.01–0.4%) with a mean log10 depletion of 2.2 (range 1.4–3). The mean recovery of CD3- and CD19-negative MNCs after depletion was 70% (range 54–88%) and the mean recovery of CD34 stem cells was 69% (range 52–98%). The mean number of natural killer (NK) cells after T- and B-cell depletion was 5.2 × 108 (range 2–10 × 108). In vitro colony assays and in vivo NOD/SCID repopulation assays showed no negative impact of this method on the function of the hematopoietic stem cells. Our results show that the CliniMACS system can be used to efficiently deplete PBSC of T and B cells simultaneously, without adverse effect on the graft.