Soluble Fc gamma receptor III (CD 16) and eicosanoid concentrations in gut lavage fluid from patients with inflammatory bowel disease: reflection of mucosal inflammation.

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Abstract
BACKGROUND--Activated neutrophils cause tissue injury in inflammatory bowel disease (IBD). Upon activation, they shed soluble Fc gamma IIIb receptors (sFc gamma RIIIb). The subsequent inflammatory response is modulated by several mediators, including neutrophil derived leukotriene B4 (LTB4), thromboxane B2 (TXB2), and prostaglandin E2 (PGE2). The aim of this study was to determine the value of gut lavage sFc gamma RIII and eicosanoid measurements for the assessment of mucosal inflammation in IBD. METHODS--A total of 18 patients with active IBD, 10 ulcerative colitis (UC), and eight Crohn's disease (CD), and 12 control patients underwent whole gut lavage. Disease activity, endoscopic appearance, and histopathology were graded. Samples were processed for the determination of sFc gamma RIIIb, LTB4, PGE2, and TXB2. RESULTS--Soluble Fc gamma RIIIb concentrations were increased in both IBD groups. Significant correlations were seen between sFc gamma RIIIb and LTB4 values with histology scores. Mean eicosanoid lavage fluid concentrations in control patients were 14.1 pg/ml for LTB4, 5.6 pg/ml for PGE2, and 397 pg/ml for TXB2. Concentrations of all eicosanoids in IBD patients were significantly increased: LTB4 in UC: mean 73.2 pg/ml, in CD: 96.4 pg/ml (both p < 0.01 v controls). PGE2 in UC: 20.2 pg/ml, in CD: 43.4 pg/ml (p < 0.01). TXB2 in UC: 719.3 pg/ml, in CD: 180.6 pg/ml (both p < 0.05). CONCLUSIONS--Whole gut lavage fluid analysis is an effective method to study mucosal eicosanoid production. Soluble Fc gamma RIIIb concentrations in gut lavage fluid closely correlate with histological signs of mucosal inflammation and with lavage LTB4 concentration. These data suggest that lavage Fc gamma RIIIb assessment may be used as a simple assay to estimate mucosal neutrophil infiltration in IBD.