CD34 and infection: It is unclear, if the ex vivo CD34+ selection of stem cells truly confers a benefit over non-selected cells.16 The potential risk of reinfusing autoreactive T-cells with non-selected grafts may be outweighed by reduced numbers of transplanted cells and increased immunosuppression in patients receiving CD34+ grafts.46 Reducing cyclophosphamide doses may on the one hand decrease toxicity in terms of infections, but on the other hand decrease the efficacy of HSCT.