FIG. 3.

In vitro chemotaxis of human neutrophils in response to live E. coli CP9 (wild type) and cell-free culture supernatant from CP9. The total deduced N-t-BOC-sensitive and the N-t-BOC-insensitive chemotaxis indices are depicted (see Materials and Methods for details on these indices). When the positive control (FMLP, 50 nM) with or without N-t-BOC was used as the chemoattractant, neutrophil chemotaxis was expressed as numbers of neutrophil events. The neutrophil response to the positive control (FMLP, 50 nM) was 30,920 ± 2,733 (mean ± SEM), of which 95% ± 1.5% was inhibited by N-t-BOC (500 μM) (number of samples, 14; data not shown on graph). Neutrophil chemotaxis toward the wild-type E. coli strain was both N-t-BOC sensitive and insensitive. In contrast, only N-t-BOC-sensitive chemotaxis was observed toward cell-free culture supernatant from the wild-type E. coli strain.