Attributes of gamma delta intraepithelial lymphocytes as suggested by their transcriptional profile

gamma delta T lymphocytes in the intestinal intraepithelial layer (gamma de lta IELs) are thought to contribute to immune competence, but their actual function remains poorly understood. Here we used DNA microarrays to study t he gene expression profile of gamma delta IELs in a Yersinia infection syst em to better define their roles. To validate this approach, mesenteric lymp h node CD8(+) alpha beta T cells were similarly analyzed. The transcription profiles show that, whereas lymph node CD8(+) ap T cells must be activated to become cytotoxic effectors, gamma delta IELs are constitutively activat ed and appear to use different signaling cascades. Our data suggest that ga mma delta IELs may respond efficiently to a broad range of pathological sit uations irrespective of their diverse T cell antigen receptor repertoire. g amma delta IELs may modulate local immune responses and participate in inte stinal lipid metabolism, cholesterol homeostasis, and physiology. This stud y provides a strong basis for further investigations of the roles of these cells as well as mucosal immune defense in general.