T-cell co-stimulatory molecules are upregulated on intestinal macrophages from inflammatory bowel disease mucosa

Background and aims Macrophages play an important role during mucosal infla mmation in inflammatory bowel disease (IBD). As the co-stimulatory molecule s B7-1 (CD80) and B7-2 (CD86) play an integral role in the activation of T cells by antigen-presenting cells (APC) we investigated the surface express ion of B7-1 and B7-2 on colonic macrophages from normal and IBD mucosa. Methods Intestinal macrophages were isolated from biopsies of 13 control pe rsons and 14 patients with IBD (seven with Crohn's disease (CD); and seven with ulcerative colitis (UC)). Cells were characterized by triple fluoresce nce flow cytometrical analysis using CD33 as macrophage marker. Results The expression of B7-1 (CD80) (9.2% a 4.2%) and B7-2 (CD86) (15.1% +/- 7.3%) was low on colonic macrophages from normal mucosa, indicating onl y a low antigen presenting potential. However, on macrophages from IBD colo n there was a significant increase in the expression of cc-stimulatory mole cules (CD80, 33.8% +/- 8.9%, P = 0.00005 vs, control; CD86, 39.9% +/- 8.8%, P = 0.00002). There was no significant difference between CD and UC in the expression of CD80 (CD, 31.3% +/- 6.7%; UC, 34.4% +/- 13.3%) and CD86 (CD, 41.9% +/- 3.8%; UC, 35.6% +/- 13.8%). While in normal mucosa only 10.6% +/ - 4.9% of the macrophages expressed CD14, more than 90% of the CD86/CD80 po sitive cells of the inflamed mucosa were positive for CD14. Conclusion Colonic macrophages from normal mucosa rarely express the co-sti mulatory molecules CD80 and CD86. In IBD a new macrophage population is fou nd with high expression of co-stimulatory molecules presumably responsible for the perpetuated immune response. Eur J Gastroenterol Hepatol 11:1105-11 11 (C) 1999 Lippincott Williams & Wilkins.