Eosinophil cationic protein in feces: Reference values in healthy and atopic individuals and patients with digestive diseases

Eosinophil cationic protein (ECP) is a good indicator of eosinophilic activity and turnover, serving as a marker of activity in allergic and gastrointestinal diseases characterized by predominantly eosinophilic tissue infiltration. Our aim was to compare ECP levels in feces from healthy individuals, atopic patients, and patients with digestive diseases and establish reference values for this clinical setting. Thirty-nine healthy adults, 28 atopic patients, and 14 patients with digestive diseases were enrolled. The atopic patients had been diagnosed with allergic rhinoconjunctivitis and/or asthma. ECP concentrations in the supernatants from processed feces adjusted for semidry weight (μg/g feces) were determined by fluorescent enzyme immunoassay. Between-group comparisons were performed of medians and interquartile ranges (IQR) by nonparametric tests. Median (IQR) ECP levels were 8.16 (4.11-17.61), 10.83 (5.18-18.49), and 13.02 (5.17-21.97) μg/g feces in controls, atopic patients, and digestive disease patients, respectively; mean (SD) levels were 14.53 (13.77), 13.93 (11.30), and 16.51 (14.79) μg/g of feces. No significant differences in the medians were observed between the atopic group and controls (p = 0.725), the atopic group and digestive disease patients (p = 0.523), or the controls versus the digestive disease patients (p = 0.694). We provide reference values for ECP levels in feces for normal and atopic adults. There is considerable variability in ECP levels in feces and the median levels are similar in healthy and atopic individuals and patients with digestive diseases.