Analysis of the expression of MICA in small intestinal mucosa of patients with celiac disease.

The MHC class I chain-related A gene (MICA) is expressed in gastrointestinal epithelium and functions as an immune activation signal under stress conditions. MICA protein binds to NKG2D, a receptor of gamma delta T cells containing the TCR variable region V(delta)1, which are the most abundant subset of T cells in the intestinal epithelium. Ingested gluten in patients with celiac disease (CD) may function as a stress signal for the epithelial cells, and could enhance MICA expression on their surface. In this study, we have analyzed MICA expression in intestinal biopsy specimens from newly diagnosed and treated CD patients and controls. Quantitative RT-PCR analysis did not show differences in MICA expression among the three groups. With these results, we conclude that overexpression of MICA does not seem to play an important role in the pathogenesis of CD, at least at the time of diagnosis.