Chemiluminescence by polymorphonuclear leucocyte subpopulations in chronic inflammatory bowel disease. Influence of the cell separation procedure

Chemiluminescence (CL) is a simple quantitative assay of polymorphonuclear leucocyte (PMNL) oxidative metabolism. PMNL CL was found to be significantly higher in patients with chronic inflammatory bowel disease than in normal controls (167 +/- 60 vs. 139 +/- 50 mV/10(5) cells, p less than 0.05). There were no significant differences between patients with ulcerative colitis and Crohn's disease. Disease controls with rheumatoid arthritis and with bronchiectasis also demonstrated elevated CL. These results were obtained using a two-step gelatin/Ficoll-Hypaque procedure for PMNL separation. However when PMNLs were prepared using a one-step Ficoll-Hypaque procedure PMNL CL was found to be depressed in chronic inflammatory bowel disease (CIBD). It was demonstrated that this disparity was caused by the elimination of low-density neutrophils with high CL production by the one-step procedure. These data indicate that reports of abnormal in vitro neutrophil function in CIBD should be interpreted with caution since separation techniques which are satisfactory in normal individuals may significantly influence results in patients with inflammatory diseases. Furthermore these data indicate the presence of a subpopulation of activated low-density PMNL in patients with CIBD.