The influence of lipofectin on the in vitro stimulation of murine spleen cells by bacterial DNA and plasmid DNA vectors

Lipofectin is a mixture of two cationic lipids, N-[1-(2,3-dioleyloxy)propyl ]-n,n,n-trimethylammonium chloride (DOTMA) and dioleoyl phosphotidylethanol amine (DOPE), and has been commonly used to promote transfection of plasmid vectors in vitro and in vivo, In these experiments, the effect of lipofect in on in vitro immunostimulation by bacterial and plasmid DNA was tested to determine if these lipids can also influence immune properites of DNA, As a model, spleen cells from BALB/c and C3H/HeJ mice were cultured with DNA f rom either Escherichia coil DNA or the pEGFP-N1 ptasmid at various ratios w ith lipofectin. As an index of immune stimulation, in vitro proliferation a s well as production of interleukin-12 (IL-12) and interferon-gamma (IFN-ga mma) were assessed. For both bacterial DNA and plasmid DNA, the presence of lipofectin led to a marked increase in the production of IFN-gamma under c onditions in which increases in IL-12 production were limited, The IFN-gamm a production was nevertheless dependent on IL-12, as shown by the effects o f anti-IL-12 antibodies. Under these culture conditions, lipofectin did not significantly augment proliferation induced by DNA, These findings indicat e that lipofectin can increase the irt vitro immunostimulatory effects of b acterial and plasmid DNA, although the magnitude of the increase may vary a mong responses.