FIG. 4.

Role of IL-8 and MCP-1 in the stimulation of neutrophil and monocyte transendothelial migration by C. pneumoniae. HUVEC monolayers cultured in transwells were inoculated with live C. pneumoniae TW-183 at a multiplicity of infection of 1:1. Mock-infected cells were treated with a suspension of lysed HEp-2 cells. Following 24 h of incubation, cells were preincubated with 10 and 20 μg of anti-IL-8 or anti-MCP-1 monoclonal antibodies per ml for 1 h before the migration assays. Transmigration of neutrophils (A) or monocytes (B) was allowed as described in the text, with the antibodies present throughout the experiments. To ensure the specificity of the monoclonal antibodies, anti-MCP-1 and anti-IL-8 at 20 μg/ml were tested for the ability to inhibit neutrophil (A) and monocyte (B) transendothelial migration, respectively. Bars indicate the means ± standard errors of the means of three separate experiments. In each experiment, triplicate wells were assayed separately for each experimental variable.