Gluten specific, HLA-DQ restricted T cells from coeliac mucosa produce cytokines with Th1 or Th0 profile dominated by interferon gamma

Abstract

Coeliac disease is precipitated in susceptible subjects by ingestion of wheat gluten or gluten related prolamins from some other cereals. The disease is strongly associated with certain HLA-DQ heterodimers, for example, DQ2 (DQ alpha 1*0501, beta 1*0201) in most patients and apparently DQ8 (DQ alpha 1*0301, beta 1*0302) in a small subset. Gluten specific T cell clones (TCC) from coeliac intestinal lesions were recently established and found to be mainly restricted by HLA-DQ2 or HLA-DQ8. Antigen induced production of cytokines was studied in 15 TCC from three patients, 10 being DQ2 and five DQ8 restricted. Cell culture supernatants were prepared by stimulation with gluten peptides in the presence of DQ2+ or DQ8+ Epstein-Barr virus transformed B cells as antigen presenting cells (APC). Supernatants were analysed for cytokines by bioassays, ELISA, and CELISA. Cellular cytokine mRNA was analysed semi-quantitatively by slot blotting and polymerase chain reaction (PCR). All TCC were found to secrete interferon (IFN) gamma, often at high concentrations (> 2000 U/ml); some secreted in addition interleukin (IL) 4, IL 5, IL 6, IL 10, tumour necrosis factor (TNF), and transforming growth factor (TGF) beta. The last TCC thus displayed a Th0-like cytokine pattern. However, other TCC produced IFN gamma and TNF but no IL 4, or IL 5, compatible with a Th1-like pattern. In conclusion, most DQ8 restricted TCC seemed to fit with a Th0 profile whereas the DQ2 restricted TCC secreted cytokines more compatible with a Th1 pattern. The TCC supernatants induced upregulation of HLA-DR and secretory component (poly-Ig receptor) in the colonic adenocarcinoma cell line HT-29.E10, most probably reflecting mainly the high IFN gamma concentrations. This cytokine, particularly in combination with TNF alpha, might be involved in several pathological features of the coeliac lesion. The characterised cytokine profiles thus support the notion that mucosal T cells activated in situ by gluten in a DQ restricted fashion play a central part in the pathogenesis of coeliac disease.