They found that although the duodenal mucosa appeared to be morphologically normal in their cohort of 14 patients with CF, the mononuclear cells in the lamina propria of the CF intestine characteristically exhibited an increased expression of immunologic markers such as intercellular adhesion molecule (ICAM)-1, IL-2 receptor, IL-2, interferon (IFN)-γ and cluster of differentiation (CD) 80, which was not observed in non-CF controls with other GI conditions. This evidence concerns the gene IFNG and cystic fibrosis.