Dose-dependent induction of IL-8 expression by TLR agonists. Human neutrophils were isolated and stimulated at the indicated doses of TLR agonists. After 3 hours of TLR stimulation, the cells were harvested for RNA. Expression of IL-8 was determined by QPCR and depicted as the number of copies of IL-8 message per copies of the control mRNA β₂-microglobulin. ○ indicates untreated cells; •, GM-CSF alone; □, cells treated with indicated TLR agonist; and ▪, cells pretreated with GM-CSF and treated with the indicated TLR agonist. Data are representative of 4 similar experiments conducted on 2 donors.