FIG. 1.

LPS binding to differentiated THP-1 cells in the presence of human serum. As described in Materials and Methods, cells were incubated with 1 μg of FITC-labeled E. coli 055:B5 LPS per ml in the presence of 0.4% BSA (bar 1), 10% human serum (bar 2), 10% human serum after preincubation of cells with isotype control IgG2a (bar 3), 10% human serum after previous incubation of cells with anti-CD14 monoclonal antibody (bar 4), 20 μg of hLf per ml (bar 5), or 10% human serum and 20 μg of hLf per ml added at the same time (bar 6). The mean fluorescence intensity was determined by flow cytometry. The results (means ± standard errors) were calculated from five separate experiments.