Immunologic profiles of effector cells and peripheral blood stem cells mobilized with different hematopoietic growth factors

Background, Peripheral blood stem cells (PBSC) have become the preferred source of stem cells for autologous transplantation because of the technical advantage and the shorter time to engraftment, Mobilization of CD34(+) cells into the peripheral blood can be achieved by the administration of G-CSF or GMCSF, or both, alone or in combination with chemotherapy, G-CSF and GM-CSF differ somewhat in the number and composition of CD34(+) cells and effector cells mobilized to the peripheral blood, However, the molecular mechanism underlying the release and engraftment of CD34(+) cells is poorly understood. Purpose. The purpose of this review is to give a recent update on the type and immunological properties of effector cells and CD34(+) cells mobilized by the different growth factors with emphasis on A) mobilization of T cells, natural killer cells, and dendritic cells; B) coexpression of adhesion molecules such as VLA-4 and L-selectin in mobilized PBSC collection, and C) coexpression of CXCR4-the receptor for the stromal-derived differentiation factor 1-with latest information shedding light on the molecular mechanism underlying the release and subsequent engraftment of CD34(+) cells. Conclusions. A) The reported suppression of T cell and NK cell functions in PBSC apheresis collections in patients primed with G-CSF or GM-CSF is controversial and may merely reflect low effector cell activity before mobilization, B) A decrease in the expression of adhesion molecules such as VLA-4 and L-selectin is a necessary requirement for the release of CD34(+) cells to the peripheral blood. C) A decrease in the expression of CXCR4 is a necessary requirement for the release of CD34(+) cells to the peripheral blood and correlates with mobilization success.