Figure 1.

Neutrophil accumulation and subsequent clearance of E. coli from the tissues is markedly delayed in a dose-dependent manner in CD. ¹¹¹Indium-labeled autologous neutrophils were injected intravenously at the same time as killed E. coli were injected subcutaneously into each forearm. (a) Radioactivity measured over the injection sites showed a much smaller proportion of labeled cells accumulating in CD subjects. (b) γ-Camera image of a CD patient at 24 h after injection, demonstrating focal accumulations of radioactivity at bacterial injection sites (arrows) and confirming lack of bowel inflammation. (c) ³²P-labeled killed E. coli were injected into the subcutaneous tissues of the forearm and radioactivity was measured at the skin surface. Clearance of radioactivity was much slower in CD than in HC or UC. Extrapolating these curves indicated that almost complete removal (99%) would take 10.2 and 7.1 d in HC and UC subjects, respectively, compared with 44.3 d in CD. (d and e) Effect of increasing bacterial dose from 10⁵ to 10⁸ on blood flow at injection site (d) and bacterial clearance (e). The numbers of subjects studied in the dose response experiment are depicted in e. All results are expressed as mean ± SEM (**, P < 0.01; ***, P < 0.001).