1. We studied neutrophil-activating peptide-1/interleukin-8 in inflammatory bowel disease.
2. Mucosal levels of neutrophil-activating peptide-1/ interleukin-8 were significantly higher in patients with active ulcerative colitis [median 74.5 (range 17.7–450.8) pg/mg] than in patients with active Crohn's disease [10.4 (4–46.9) pg/mg; P<0.002] or in normal control subjects [10.4(4–16.6) pg/mg; P <0.002].
3. Circulating neutrophil-activating peptide-1/interleukin-8 was generally undetectable but there were higher levels of anti-neutrophil-activating peptide-1/interleukin-8 antibodies in patients with active ulcerative colitis [62.9 (3.4–239) ng/ml] than in patients with active Crohn's disease [5.9 (2.1–18.10) ng/ml; P <0.001] or in control subjects [6.1 (3.2–15.8) ng/ml; P <0.001].
4. Neutrophil-activating peptide-1/interleukin-8 may be of specific functional importance in mediating inflammation in ulcerative colitis.