Immunohistochemical findings in the jejunal mucosa of patients with coeliac disease

In the pathogenesis of coeliac disease, disturbed immunological processes p lay a basic role. This is also proved by immunohistochemical findings in th e jejunal mucosa of patients with this disorder, which are discussed in thi s review. Intraepithelial lymphocytes are increased in number in active coe liac disease, most being of the CD8 subpopulation. The counts of lamina pro pria lymphocytes and the relative numbers of their subsets are comparable t o those in healthy controls, but several studies have indicated that the de nsities of IgA, IgM and IgG immunoglobulin-containing cells in the lamina p ropria are increased in untreated coeliac disease. Activated T cells can al so be found in the lamina propria of patients on gluten-containing diets. I n the crypt epithelial cells of coeliac patients on normal diets, strong ex pression of HLA Class II antigens can be observed. All of these changes are normalized on a gluten-free diet. It was recently discovered by the author s and others that one of the hallmarks of coeliac disease, both active and treated, is an increase in number and proportion of gamma/delta intraepithe lial T lymphocytes. The permanent increase of gamma/delta T cells may facil itate identification of a coeliac patient also when an intestinal biopsy is taken on a gluten-free diet and other morphologic signs are normalized. Th e detection of elevated numbers of intraepithelial gamma/delta T cells is a lso an indispensable help in the diagnosis of latent coeliac disease.