[An effective method for T-cell and B-cell simultaneous depletion in vitro from mobilized peripheral blood...

Depletion of T and B cells from the graft is prerequisite for haploidentical transplantation to decrease the risk of GVHD and EBV-associated lymphoproliferative disease. This study was aimed to investigate the performance of T-cell and B-cell simultaneous depletion from mobilized peripheral blood stem cells (PBSCs) for the first time in China, using anti-CD3 and anti-CD19 antibodies conjugated to magnetic microbeads by the CliniMACS device. The depletion efficiency of T-cell and B-cells was analyzed by flow cytometry; the function of the stem cells after depletion was evaluated using colony assays. The results indicated that the mononuclear cell count prior to T- and B-cell depletion was 4.88 x 10(10). After depletion, the percentage of T cells was 0.02% with a log (10) depletion of 4.4. The percentage of B cells was less than 0.01% with a log (10) depletion of at least 3.3. The product contained not only CD34(+) stem cells, but also NK cells, monocytes and granulocytes. After T- and B-cell depletion the purity of CD34(+) cells was 0.98%, the number of CD34 cells was 1.84 x 10(8) and their recovery rate was 69.7%. The number of NK cells was 2.54 x 10(9) and the recovery rate of NK cells was 71.7%. In vitro colony assays showed no negative impact on function of the hematopoietic stem cells. In conclusion, the CliniMACS system can be used to efficiently deplete T and B cells from PBSCs simultaneously, without adverse effect on biological function of hematopoietic stem cells. This study provides technical platform for haploidentical hematopoietic stem cell transplantation.