Plasmacytoid dendritic cells (pDCs) from SLE patients treated with prostaglandin E2 (PGE2) inhibited the expression of IFNα, and coculturing PGE2-treated pDCs with Th1 cells significantly suppressed secretion of IFNγ, indicating that IFNα is involved in PGE2-mediated inhibition of Th1 response (12). The gene discussed is IFNA1; the disease is systemic lupus erythematosus.