In Situ Rantes and Interferon‐γ Gene Expression in Pediatric Small Bowel Crohn's Disease

Abstract

BackgroundRantes (regulated upon activation, normal T cell expressed and secreted) is a chemotactic cytokine for memory T lymphocytes, monocytes, and eosinophils. The cytokine interferon‐γ (IFN‐γ) plays a key in the immune response. Their distributions and possible roles in the selective accumulation of inflammatory cells in Crohn's disease (CD) were examined by determining the expression of Rantes and IFN‐γ genes in patients with CD using in situ hybridization (ISH) on frozen and paraffin‐embedded tissue sections.MethodsIntestinal and mesenteric lymph node samples from 9 children who had undergone ileal resection for CD were examined for the presence of epithelioid‐giant cell granulomas (EGCG) and Rantes and IFN‐γ messenger RNA (mRNA). Normal pediatric intestine (n = 5) and lymph nodes (n = 2) served as controls.ResultsMany cells in all CD specimens in the epithelial compartment, lamina propria, and the EGCG gave positive signal with the Rantes antisense probe. Labelled cells were identified on paraffin sections as lymphocytes, macrophages, and epithelioid cells. There were Rantes‐positive cells in the control intestinal tissues, but many Rantes‐positive cells in control lymph nodes that showed follicular hyperplasia. IFN‐γ‐positive cells were present in all CD ileal and lymph node specimens, predominantly in close contact with EGCC. No positive signal was obtained with the Rantes and IFN‐γ sense control probes.ConclusionsThese findings suggest that Rantes and IFN‐γ contribute to the selective accumulation of macrophages and memory T helper lymphocytes inside the granulomas and inflammatory infiltrates that are characteristic of CD.