Interleukin-10 Inhibits Spontaneous Colony-Forming Unit–Granulocyte-Macrophage Growth From Human Peripheral Blood Mononuclear Cells by Suppression of Endogenous Granulocyte-Macrophage Colony-Stimulating Factor Release

Abstract

Spontaneous growth of myeloid colonies (colony-forming unit–granulocyte-macrophage [CFU-GM]) can be observed in methylcellulose cultures containing peripheral blood mononuclear cells (PB-MNCs) and is supposedly caused by the release of colony-stimulating factors (CSF ) by accessory cells. Because of its cytokine synthesis-inhibiting effects on T lymphocytes and monocytes, interleukin-10 (IL-10) may be a potential candidate for indirect modulation of hematopoiesis. We studied the effect of recombinant human IL-10 (rhIL-10) on spontaneous growth of myeloid colonies derived from human PB-MNCs. A total of 10 ng/mL of IL-10 almost completely inhibited spontaneous CFU-GM proliferation (by 95.1%; P < .001, n = 7) in unseparated PB-MNCs. This effect was dose-dependent and specific, because a neutralizing anti–IL-10 antibody was able to prevent IL-10–induced suppression of CFU-GM growth. Spontaneous CFU-GM growth, which required the presence of both monocytes (CD14+ cells) and T lymphocytes (CD3+ cells), was also greatly suppressed by a neutralizing anti–granulocyte-macrophage CSF (GM-CSF ) antibody but was only slightly or not at all inhibited by antibodies against G-CSF or IL-3. Moreover, IL-10–suppressed colony growth could be completely restored by the addition of exogenous GM-CSF. Using semiquantitative polymerase chain reaction, we were able to show that GM-CSF transcripts that spontaneously increased in PB-MNCs within 48 hours of culture were markedly reduced by the addition of IL-10. Inhibiton of GM-CSF production in PB-MNCs by IL-10 was also confirmed at the protein level by measuring GM-CSF levels in suspension cultures. Our findings suggest that autonomous CFU-GM growth, resulting from an interaction of monocytes and T lymphocytes, is mainly caused by endogenous GM-CSF release and can be profoundly suppressed by the addition of exogenous IL-10. Considering the strong inhibitory action of IL-10 on GM-CSF production and spontaneous cell growth in vitro, this cytokine may be useful in myeloid malignancies in which autocrine and/or paracrine mechanisms involving GM-CSF are likely to play a pathogenetic role.

Peritoneal macrophage from male and female SJL mice differ in IL-10 expression and macrophage maturation

“…A direct role of increased IL-10 secretion by the antigen-positive CD11b lo F4/80 lo cells in polarizing the T cell response is not clear; however, blocking IL-10 increased the Ly6C Ϫ subset of CD11b lo F4/80 lo cells, suggesting that endogenous IL-10 prevents macrophage maturation, possibly via alterations in GM-CSF. Macrophage maturation is dependent on GM-CSF, which is influenced adversely by IL-10 [27,28]. In contrast to the inhibitory effect of IL-10 on macrophage maturation, a potentiating effect of IL-10 on macrophage maturation has been described [29,30], including the increased differentiation of CD16-positive macrophages from human blood monocytes cultured in the presence of IL-10 [29].…”

Comorbidity predicts survival in myelodysplastic syndromes or secondary acute myeloid leukaemia after allogeneic stem cell transplantation

“…The numbers of haematopoietic progenitor cells were determined at diagnosis and 28 days after SCT from BM aspirates according to the standard protocol described previously [37].…”

Dasatinib inhibits progenitor cell proliferation from polycythaemia vera

“…Exogenous cytokines such as rhGM-CSF and rhIL-3, which are used in our semisolid colony assay, augment the growth of granulocyte/macrophage-colony forming units (CFU-GM) [18]. Since myeloid progenitors belong to the population of clonal cells in PV we investigated the effect of increasing concentrations of dasatinib on CFU-GM formation.…”