To investigate the ability of pDCs to trigger cytokine production by T cells, we first co-cultured pDCs from patients with active SLE, At-Risk individuals, and healthy controls with allogeneic naive CD4+ T cells in the presence of low ratio anti-CD3/CD28 beads for 5 days before adding PMA/Ionomycin in the last 5 h of the culture. This evidence concerns the gene CD28 and systemic lupus erythematosus.