Toll like receptor 4 ligation promotes B7 family costimulatory molecules expression in a time and cytokine dependent fashion

Abstract

Abstract Introduction The interplay between costimulatory and coinhibitory molecules allows adequate integration of instructions for T cell fate. In this study, we explored how antigen concentration and time exposition to a pathogen associated molecule pattern may modulate the expression of B7 family costimulatory molecules CD86, ICOSL, PDL1, PDL2 and the Interferon Regulatory Factor 4 in human monocyte-derived dendritic cells (MoDCs). Methods MoDCs were obtained from healthy donors. MoDCs were stimulated with different concentrations of E. coli lipopolysaccharide and stimulated for 12, 24 or 48 h. Supernatant from stimulated MoDCs were collected for soluble cytokines determination using cytometric bead arrays. Cells were collected and membrane stained with fluorochrome-conjugated monoclonal antibodies to evaluate PDL1, PDL2, CD86 and ICOSL trough flow cytometry. Intracellular staining was performed for IRF4 after cell permeabilization. Results TNF α and IL-6 were significantly increased at 12 h, while IFN-γ and IL-2 were increased at 48 h. Costimulatory molecules showed a differential expression pattern. ICOSL was preferentially incremented at 48 h post stimuli independently of concentration used. PDL1 was induced at low concentrations and short stimulation periods, maintaining their expression all along with the stimulation kinetic. PDL2 increased its expression at short time of stimulation. CD86 and IRF4 did not show statistically significant differences. Conclusion Our results suggest that costimulatory molecules have time-dependent expression profile, possibly influenced by the cytokines contained in the microenvironment and a lesser by the antigen concentration.