Flt3 ligand induces monocyte proliferation and enhances the function of monocyte-derived dendritic cells in vitro
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Published on: April 11, 2025
Sung-Whan Kim1, Seong-Mi Choi, Yee Shin Choo
1Institute for Bio-Medical Convergence, College of medicine, Catholic Kwandong University, Incheon, Korea; Innovative Cell & Gene Therapy Center, International St. Mary's Hospital, Incheon, Korea.
Insights
Flt3 ligand (FL) enhances human monocyte survival and proliferation, primarily through ERK signaling. FL-treated monocytes yield more functional dendritic cells (DCs) with improved T-cell stimulation, offering potential immunotherapeutic benefits.
Area of Science:
- Immunology
- Cell Biology
- Hematopoiesis
Background:
- Flt3 ligand (FL) is a key hematopoietic cytokine for dendritic cell (DC) and natural killer (NK) cell development.
- The precise role of FL on human peripheral blood monocytes and their derived DCs remains incompletely understood.
- Previous research has characterized some post-receptor signaling events of FL, but its direct impact on monocytes requires further elucidation.
Discussion:
- FL significantly promotes human monocyte proliferation in a dose-dependent manner and inhibits spontaneous apoptosis.
- FL-induced monocyte growth is mediated by ERK phosphorylation, with minimal effects observed on p38 MAPK, JNK, and AKT pathways.
- FL addition during DC generation from monocytes increases DC yield via enhanced cell proliferation.
Key Insights:
- FL-generated DCs exhibit increased surface expression of costimulatory molecules.
- These FL-enhanced DCs stimulate allogeneic T cell proliferation in mixed lymphocyte reactions (MLR) more effectively.
- FL demonstrates a partial antagonistic effect on IL-10-mediated inhibition of DC function.
Outlook:
- Further investigation into FL's mechanisms on monocytes and DCs could reveal novel immunotherapeutic strategies.
- Harnessing FL's effects may lead to improved DC-based vaccines and therapies.
- Understanding FL signaling pathways is crucial for optimizing DC-based immunotherapies.
Abstract:
Flt3 ligand (FL), a potent hematopoietic cytokine, plays an important role in development and activation of dendritic cells (DCs) and natural killer cells (NK). Although some post-receptor signaling events of FL have been characterized, the role of FL on Flt3 expressing human peripheral blood monocyte is unclear. In the current study, we examined the role of FL on cell survival and growth of peripheral blood monocytes and function of monocyte-derived DCs. FL promoted monocyte proliferation in a dose-dependent manner and prevented spontaneous apoptosis. FL induced ERK phosphorylation and a specific ERK inhibitor completely abrogated FL-mediated cellular growth, while p38 MAPK, JNK, and AKT were relatively unaffected. Addition of FL to GM-CSF and IL-4 during DCs generation from monocytes increased the yield of DCs through induction of cell proliferation. DCs generated in the presence of FL expressed more costimulatory molecules on their surfaces and stimulated allogeneic T cell proliferation in MLR to a higher magnitude. Furthermore, FL partially antagonized IL-10-mediated inhibition on DCs function. Further characterization of FL actions may provide new and important information for immunotherapeutic approaches utilizing DCs.
