Differences in the T-bet and GATA-3 expression patterns between lymphocytic colitis and coeliac disease

Lymphocytic colitis (LC) is a disease of unknown aetiology. Among other pathogenetic possibilities, an abnormal reaction to a luminal antigen has been discussed. To clarify this fact, we characterized the inflammatory infiltrate in LC and compared it with the Th1 response-related coeliac disease (CD). Biopsies from 10 LC and 10 CD patients were analyzed by immunohistochemistry for detection of T-bet, the master regulator of Th1 response and its antagonist GATA-3 in T cells employing double labellings. In LC, 10-20% of intraepithelial lymphocytes (IEL) expressed GATA-3 and the remaining T-bet, whereas in CD, all IEL were T-bet-positive. The T cells in the lamina propria of LC (65-70% CD4+; 30-35% CD8+) showed a mixed expression pattern of T-bet and GATA-3. The majority of the CD4+ T cells were GATA-3+, while T-bet and GATA-3 were expressed at a similar frequency by the CD8+ T cells. Most of the T cells in the lamina propria of CD specimens were CD4+, showing a predominant T-bet expression. Also, most of the CD8+ lamina propria T cells in CD were T-bet+. We conclude that in contrast to CD, which exhibits immunophenotypical features of a Th1-response, LC shows features of a mixed Th1/Th2 immune response.