FIG. 4.

Expression of both mTLR4 and mMD-2 imparts responsiveness to Salmonella lipid A. THP-1 cells were transiently transfected with either a control vector alone (mock) or plasmids for mCD14 and mMD-2, mCD14 and mTLR4, or mTLR4 and mMD-2 (0.1 μg each) together with the pELAM-L luciferase reporter plasmid. After 24 h, the cells were stimulated for 6 h without (none) or with 10 ng of E. coli lipid A/ml (ELA) or 100 ng of Salmonella lipid A/ml (SLA) in the presence of 10% (vol/vol) FCS, and the luciferase activities were measured. The values are means ± standard errors of the means from at least four independent experiments. ∗, P < 0.05; ∗∗, P < 0.01 (compared with the respective responses in mock-transfected cells by two-tailed Student's t test).