Abstract: Objective To test the effect of bifunctional molecule IL2-GMCSF in promoting the activation of dendritic cells (DCs)
cultured in tumor conditioned medium. Methods We prepared a tumor conditioned medium using mouse melanoma cell line
B16F10 supplemented with IL2-GMCSF, GM-CSF, IL-2, or the combination of the latter two. After culturing mouse DC cell line
DC2.4 in the conditioned medium for 24 h, the DCs were examined for phagocytosis, proliferation, maturation phenotype,
cytokine secretion, and signal pathway activation. Results DC2.4 cells displayed characteristics of immature DCs. After cell
culture in the conditioned medium, the cells showed enhanced phagocytosis but significantly suppressed cell proliferation
activity. Culture in the conditioned medium also promoted DC cell maturation and secretion of macrophage-derived
chemokine (MDC), but inhibited IL-12 secretion. Supplementation of the conditioned medium with IL2-GMCSF promoted
phagocytosis, proliferation, maturation, and cytokine (including both IL-12 and MDC) secretion of DC2.4 cells. Compared with
GM-CSF, IL2-GMCSF induced a higher level of NF-κB signal pathway activation but suppressed STAT3 activation. Conclusion
Compared with GM-CSF, IL2-GMCSF can better promote DC activation in the context of tumor-induced immune suppression,
and thus shows potentials in anti-tumor therapy.