Figure 2. Synergistic effect of histamine for IL-8 production from gingival fibroblasts stimulated with TNF-, IL-1, and LPS. Gingival fibroblasts were incubated with 100 µmol/L of histamine (His) or medium (Med) for 2 hrs. The cells were then stimulated with TNF- (A), IL-1 (B), or LPS (C) at the indicated concentrations in the presence or absence of histamine at 100 µmol/L for 6 hrs for TNF- and IL-1 or 22 hrs for LPS. After the incubation, supernatants were collected, and the concentrations of IL-8 in the supernatants were determined by ELISA. The results are expressed as the mean ± SD for triplicate cultures. *p < 0.01 compared with MedHis. #p < 0.05 and ##p < 0.01 compared with MedTNF-, MedIL-1, or MedLPS.