Peripheral blood mobilization of different lymphocyte and dendritic cell subsets with the use of intermediate doses of G-CSF in patients with non-Hodgkin's lymphoma and multiple myeloma

Between June 2003 and November 2004, we collected mobilized peripheral blood units from 29 patients with non-Hodgkin's lymphoma and multiple myeloma for autologous peripheral blood stem cell transplantation. They received granulocyte colony-stimulating factor (G-CSF) (16 μg/kg/day) for a total of 5 days. Immediately before and 3 h after the fourth and fifth dose of G-CSF, we performed flow cytometry analysis to quantify: T cells (CD3+CD4+, CD3+CD8+), B cells (CD19+), NK cells (CD3-CD16+CD56+), NKT cells (CD3+CD16+CD56+), type 1 dendritic cells (DC1) (lin-HLA-DR+CD11c+), type 2 dendritic cells (DC2) (lin-HLA-DR+CD123+), regulatory T cells (Tregs) (CD4+CD25+), and activated T cells (CD3+HLA-DR+). All cell subsets were mobilized after G-CSF treatment with the exception of B, NK, and NKT lymphocytes. The median number of Treg cells before and after G-CSF was statistically different (29±14.9×10⁶/l vs 70.1±46.1×10⁶/l, P<0.02). DCs were mobilized significantly with a 5.9-fold increase in DC2 (15.1±30.3×10⁶/l vs 89.8±81.0×10⁶/l, P<0.02) and a 2.6-fold increase for DC1 (41±42.5×10⁶/l vs 109.5±58.0×10⁶/l, P<0.04). Patients received a mean of 3.1±1.2×10⁷/kg NK cells, 1.3±0.9×10⁷/kg NKT cells, 0.41±0.29×10⁷/kg DC1, 0.2±0.22×10⁷/kg DC2, and 1.8±1.9×10⁷/kg Tregs. In conclusion, intermediate doses of G-CSF induce mobilization of different lymphocyte subsets, with the exception of B, NK, and NKT cells. The mobilization of certain suppressive populations (DC2 and Treg) could be in theory deleterious, at least in patients with cancer.