DC-mediated growth inhibition is mediated by DC-tumor contact while enhancement effect of LPS is caused mainly by soluble factors.
(A) DCs at 0.5 × 106 cell/well were incubated in 24-well plates with or without LPS. At 24 hours, HT29 cells (0.1 × 106 cells/well) were added to either outer well (with DCs) or inner well separated from DC by a membrane with 0.45 μm pore size. (B) DCs were cultured without or without 5 μg/mL of LPS in a flat-bottom 96-well plate. At 24 hours, 100 μL of undiluted supernatants was transferred to the well with indicated tumor cells at 1 × 104 cells/well. The plates were further incubated for 48 hours, and cell proliferation was measured by3H-TdR incorporation. The results are presented as the mean ± SD of triplicate wells. The results of 3 representative experiments using DCs from different donors are shown. *P < .05 compared with DCs cultured with medium.
