Intraepithelial lymphocytes (IELs) bearing the γδ TCR are more abundant in the small intestinal mucosa of patients with celiac disease (CD) compared with healthy individuals. However, their role in disease pathogenesis is not well understood. Here, we investigated the functional attributes of TCRγδ+ IELs isolated from intestinal biopsies of patients with either active celiac disease (ACD) or those on a gluten-free diet (GFD). We found that compared with individuals with ACD, individuals on GFD have a higher frequency of CD8+TCRγδ+ IELs that express the inhibitory NK receptor NKG2A and intracellular TGF-β1. TCR triggering as well as cross-linking of NKG2A increased both TGF-β1 intracellular expression and secretion in vitro. Coculture of sorted TCRγδ+NKG2A+ IELs, IL-15–stimulated TCRαβ+ IELs, and HLA-E+ enterocytes resulted in a decreased percentage of cytotoxic CD8+TCRαβ+ IELs expressing intracellular IFN-γ and granzyme-B and surface NKG2D. This inhibition was partially abrogated by blocking either TGF-β alone or both NKG2A and HLA-E. Thus, our data indicate that suppression was at least partially mediated by TGF-β secretion as a result of engagement of NKG2A with its ligand, HLA-E, on enterocytes and/or TCRαβ+ IELs. These findings demonstrate that human small intestinal CD8+TCRγδ+ IELs may have regulatory potential in celiac disease.
Govind Bhagat, Afzal J. Naiyer, Jayesh G. Shah, Jason Harper, Bana Jabri, Timothy C. Wang, Peter H.R. Green, John S. Manavalan
This file is in Adobe Acrobat (PDF) format. If you have not installed and configured the Adobe Acrobat Reader on your system.
PDFs are designed to be printed out and read, but if you prefer to read them online, you may find it easier if you increase the view size to 125%.
Many versions of the free Acrobat Reader do not allow Save. You must instead save the PDF from the JCI Online page you downloaded it from. PC users: Right-click on the Download link and choose the option that says something like "Save Link As...". Mac users should hold the mouse button down on the link to get these same options.