To detect the expression of TLR3 in LPS-induced AMΦ, which were isolated from the bronchoalveolar lavage fluid (BALF) of wild-type (WT) mice, LPS was administered at 5 different dosages (0, 0.01, 0.1, 1, and 10 μg/ml). TLR3 expression increased with 0.1 μg/ml but was markedly increased following treatment with 1 μg/ml LPS, and the increase in TLR3 expression trended back to the basal level at 10 μg/ml LPS (Fig. 1A,B). As shown in Fig. 1C, a 1 μg/ml LPS challenge of AMΦ from WT mice was associated with an increase in TLR3 protein expression at 4 h and a more marked increase at 6 h, while the increase in TLR3 expression trended back to the basal level at 8 h. The TLR3 mRNA expression changes shown in Fig. 1D paralleled the protein expression changes. In addition, we obtained the same results using quantitative PCR (Fig. 1E,F). These results suggest that LPS, a TLR4 ligand, can induce TLR3 expression in AMΦ.