Effect of LPS and various cytokines on the proliferative response in DC cultures. Myeloid-enriched non-T cells were cultured in the presence of various cytokine combinations, then washed and reincubated for 18 hours with [³H]-TdR. Where added, LPS or TNF were included during the final 24 hours of culture. Control cells were cultured with GM-CSF and IL-4, and treated with mitomycin C before assay. Proliferation is represented as the mean [³H]-TdR incorporation of triplicate wells. The data presented are representative of three separate experiments. (□), Medium; (▪), GM-CSF; (○), GM-CSF + IL-4; (•), GM-CSF/IL-4 + LPS; (▴), GM-CSF/IL-4 + TNF; (▵), control.