OBJECTIVES: The aim of the study was to investigate the characteristics of intestinal immune activation (ie, a chemokine receptor and cytokine expression profile) in delayed-type cow's milk allergy (CMA) appearing in the form of gastrointestinal symptoms. PATIENTS AND METHODS: In all biopsy samples taken from the duodenum and/or the terminal ileum, 30 were studied for the expression of interferon-gamma, transforming growth factor-beta, chemokine receptor (CCR)-4, CCR-5, IL-2, IL-6, IL-10, IL-12p35, IL-12p40 and IL-18 specific mRNA by real-time quantitative reverse transcriptase-polymerase chain reaction in 26 children ages 3 to 15 years: 10 with untreated delayed-type CMA, 6 with celiac disease (CD) and 10 controls. RESULTS: The children with delayed-type CMA showed lower IL-2 and IL-18 mRNA expression in the duodenum (both P = 0.055) and higher CCR-4 and IL-6 mRNA expression in the terminal ileum (P = 0.055, P = 0.016) compared with the controls. The children with CD exhibited slightly higher expression of interferon-gamma and CCR-4 mRNA (P = 0.054, P = 0.053) and lower expression of IL-18 mRNA (P = 0.004) in the duodenal samples compared with the controls. The mRNA expression levels of regulatory cytokines, transforming growth factor-beta and IL-10 remained similar in all 3 groups. CONCLUSIONS: The children with delayed-type gastrointestinal CMA showed a unique pattern of local intestinal hypersensitivity with Th2 response-related characteristics, a profile differing clearly from the children with CD. © 2006 Lippincott Williams & Wilkins, Inc.