The effect of manufactured gold nanoparticles (NP) on the immune system was analysed through their ability to perturb the functions of dendritic cells (DC), a major actor of both innate and acquired immune responses. For this purpose, DCs were produced in culture from mouse bone marrow progenitors.The analysis of the viability of the cells after their incubation in the presence of gold NP shows that these NP are not cytotoxics even at high concentration. Furthermore, the phenotype of the DC is unchanged after the addition of NP, indicating that there is no activation of the DC. But the analysis of the cells at the intracellular level reveals important amounts of gold NP amassing in endocytic compartments. Furthermore, the secretion of cytokines is significantly modified after such internalisation indicating a potential perturbation of the immune response.