Fig. 1. Characterization of 26ic PE-Fab probe. PE-Fab probe against CD14 was characterized using HPLC (A) and flow cytometry (B-E). HPLC size exclusion chromatography separated the 1:1 labelled PE-Fab (1), from free PE (2) and from free Fab (3). The arrow indicates the fractions collected for further analysis. For testing the binding of the PE-Fab conjugate, CHO-CD14 cells were incubated with no probe (B), 40 nM of PE-labelled Fab (C), 40nM unconjugated PE (D) or 40 nM of PE-Fab in the presence of 10 ng ml^-1 of unlabelled LPS (E). 10,000 cells were analysed for fluorescence on a FACalibur flow cytometer. The histograms display relative cell numbers (y axis) as a function of relative fluorescence intensities (x axis).