Expression of the High-Affinity IgG Receptor FcRI (CD64) in Patients With Inflammatory Bowel Disease: A New Biomarker for Gastroenterologic Diagnostics

OBJECTIVES: We sought to determine the quantitative expression of the high-affinity Fc receptor (CD64) on polymorphonuclear neutrophils (PMNs) in inflammatory and functional conditions of the intestine and investigated its correlation with clinical and biological parameters of inflammation. METHODS: The quantitative expression of CD64 was determined by fluorescence-activated cell sorting analysis in patients with active or inactive inflammatory bowel disease (IBD, n = 76), infectious enterocolitis, lactose and/or fructose intolerance, and healthy subjects. RESULTS: The quantitative expression of CD64 in patients with active IBD (3,398 +/- 3,589 molecules per PMN, n = 27) was significantly higher than in healthy subjects (607 +/- 265, n = 28, P < 0.001) or in patients with lactose/fructose intolerance (531 +/- 150, n = 32, P < 0.001). The expression of CD64 correlated significantly with C-reactive protein (CRP, 0.65, P < 0.0001), Crohn's disease activity index (CDAI, 0.53, P < 0.0001), and colitis activity index (CAI, 0.63, P < 0.0001) in patients with IBD. With a cutoff point of 800, CD64 had a sensitivity of 88 % and a specificity of 93 % in discriminating between lactose/fructose intolerance and active IBD. The quantitative expression of CD64 in patients with infectious enterocolitis (19,190 +/- 8,920, n = 22) was significantly higher than in patients with active IBD (P < 0.001). With a cutoff point of 10,000, CD64 showed a sensitivity of 96 % and a specificity of 97 % in discriminating between infectious enterocolitis and active IBD. CONCLUSIONS: CD64 could serve as a valuable tool to discriminate between IBD, infectious enterocolitis, and functional intestinal disorders.