Figure 8.

Histamine priming enhances the responsiveness of endothelial cells to TLR2 and 4 ligands. HUVEC (1 × 10⁴ cells) were plated on to each of the wells of a 96-well culture plate and allowed to adhere for 18–20 hr. HUVEC monolayers were incubated with medium or histamine (10 μm) for 16 hr, and then activated with LPS (100 ng/ml), or PGN (100 μg/ml) for an additional 24 hr. After the incubation, IL-6 levels in the culture media were assayed. Each value presented is the mean ± SD of quadruplicate determinations. The results presented are representatives of three independent experiments. An asterisk indicates P < 0·01 when compared to value for medium-treated cells.