Effect of cationic lipids on cell-associated ODN. Blood-derived mononuclear cells were incubated for 2 hours with increasing amounts of radiolabeled ODN in the absence (○) or presence (•) of DOTAP (A) or DOSPER (B). The amount of cell-associated ODN was measured by liquid scintillation counting of cellular extracts. (C) Analysis of extracts from cells incubated with ODN/DOSPER complexes by denaturing 12% polyacrylamide gel electrophoresis. Full-length 23-mer ODN are indicated.