Figure 2.

H. influenzae activates a response element in the ICAM-1 gene. (A) Gene promoter activity was assessed using plasmids containing a luciferase gene driven by a heterologous minimal promoter (either TA or TK). The luciferase reporter plasmid without or with the H. influenzae response element (HFRE) (nucleotides −200 to −135 of the ICAM-1 gene sequence) placed 5′ to the minimal promoter was transfected into hTBE cells. Cells were then incubated without or with H. influenzae for 18 hours and luciferase activity was measured. (B) Gene promoter activity was assessed by transfecting hTBE cells with a plasmid containing a luciferase gene driven by ICAM-1 gene sequence from −1294 to +7 without or with mutation of the AP1-, C/EBP-, or NF-κB–binding sites in or nearest to the HFRE. Cells were then incubated without or with H. influenzae for 18 hours and luciferase activity was measured. Values in both panels are expressed as mean fold induction in luciferase activity relative to uninfected cells ± SD (n = 3–6 experiments, each with duplicate samples), and a significant difference from levels with constructs driven by TA or TK heterologous promoters alone in A and the unmutated construct in B is indicated by an asterisk.