In vivo induction of T-cell hyporesponsiveness and alteration of immunological cells of bone marrow grafts using granulocyte colony-stimulating factor

Abstract

BACKGROUND AND OBJECTIVES: Granulocyte colony-stimulating factor (G-CSF)-primed bone marrow (G-BM) transplantation is associated with a low incidence of graft-versus-host disease (GVHD) and has been used successfully in patients with human leukocyte antigen (HLA) matched/mismatched donors. This study evaluated the function of T cells and the quantities of immunological cells of G-BM. DESIGN AND METHODS: Bone marrow was obtained from fifteen donors by aspiration. Lymphocyte proliferation ability, interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) secreted by T cells were determined using a monotetrazolium (MTT) assay and sandwich enzyme-linked immunosorbent assay (ELISA), respectively. T-cell subgroups, dendritic cell (DC) subsets, CD4(+)CD25(+) regulatory T cells and the expression of CD28/CD80/CD86 molecules on monocytes, B and T cells were analyzed using flow cytometry. RESULTS: G-CSF treatment decreased the quantities of IFN-gamma secretion dramatically (p=0.007) and IL-4 moderately (p=0.027), leading to higher ratios of IL-4/IFN-gamma (p=0.004). We confirmed T-cell hyporesponsiveness and lower expression of CD28/CD80/CD86 on monocytes, B and T cells. The absolute values of lymphocytes, T cell subgroups, CD3+CD4-CD8- cells, CD8+CD28- cells and B cells in bone marrow grafts were similar before and after G-CSF treatment. The number of monocytes per microliter was increased 2.13-fold, while the numbers of CD4(+)CD25(+) regulatory T cells were unchanged. DC2 were preferentially increased. INTERPRETATION AND CONCLUSIONS: Our results suggest that bone marrow T-cell hyporesponsiveness could be induced and that the increase of monocytes and DC2 and the downregulation of CD28/CD80/CD86 co-stimulatory signals were produced by in vivo use of G-CSF; this may be related to the preferential increase of monocytes and DC2 and the downregulation of CD28/CD80/CD86 co-stimulatory signals.