Comparison between G-CSF and GM-CSF for Mobilization of Dendritic Cells, CD34+ Cells, and CD3+ Cells in Normal Donors.

Donor lymphocyte infusions (DLI) can induce an allo-immune mediated graft-versus-malignancy (GVM) effect in patients (pts) that relapse after allogeneic stem cell transplantation (ASCT). Dendritic cells (DC) are effective antigen presenting cells and an important regulatory element of T-cell mediated immune responses. Previously, we have shown that NHL pts given GM-CSF mobilized up to 5 fold more immature DC (CD14+CD80+ cells) compared to G-CSF mobilization (Gazitt et al. J. Hematother. Stem Cell Res. 2001. 10:177). We hypothesized that increasing the DC populations in DLI may augment the GVM effect, particularly if GM-CSF mobilization resulted in increased DC1 cells. We designed a pilot study to treat pts with relapsed disease after ASCT with GM-CSF mobilized DLI. Total DC, DC1, DC2, and CD34+cells from the same donor were compared from G-CSF mobilized peripheral blood stem cell (PBSC) collections and GM-CSF mobilized DLI collections. Donors received G-CSF 10 ug/kg/day for 5 days prior to PBSCH, and GM-CSF 500 ug/day for 5 days prior to DLI collection. All donors were HLA matched related siblings and DLI was collected when pts demonstrated relapse or persistent disease after ASCT. Total DCs were defined as CD80+CD14- cells, DC1 cells as CD11c+HLADR+lin-, and DC2 cells as CD 123+HLADR+lin-. Analysis was done by flow cytometry using a 3 color assay. No unexpected adverse events occured to the donors who received GM-CSF prior to DLI collection or to the pts during DLI administration. Diseases of patients prior to ASCT were CML accelerated phase (n=1), high risk acute leukemia (n=4), chemotherapy refractory NHL (n=2) and refractory multiple myeloma (n=1). Four of 8 pts developed aGVHD (grade II: n=3, and grade IV: n=1). Three patient had remissions post DLI for 1 to 6 months. Subsequently, seven pts died of progressive malignacy and 1 pt died of sepsis with no active GVHD or malignancy. The mean number of cell types collected for the G-CSF and GM-CSF apheresis collections are described in the table below. Mobilization with G-CSF resulted in up to a 10 fold larger number of CD34+ cells/kg and 3–5 fold larger number of total DC, DC1 and DC2 cells within the same donor compared to GM-CSF. The ratio of DC1 to DC2 in each donor remained constant in both the G-CSF and GM-CSF mobilized apheresis products. We conclude that GM-CSF mobilization results in adequate collection of CD3+ cells for DLI, and infusion of these cells is tolerated well. In this small sample of normal donors it appears that G-CSF mobilizes more CD34+, total DC, DC1 and DC2 cells within the same donor compared to GM-CSF, with no polarization by G-CSF or GM-CSF for either DC1 or DC2 cells.

Mean cell counts/kg x 10⁶ (range)