In conclusion, our findings show that high levels of IL-10 in the serum of SLE patients significantly alters the phenotype, cytokine profile and the allostimulatory capacity of MDDCs, resulting in decreased expression of HLA-DR and CD80, reduced production of IL-12p40, increased production of IL-10 and a decreased capacity to stimulate allogenic T-cell proliferation. This evidence concerns the gene CD80 and systemic lupus erythematosus.