Dendritic cells promote expansion and survival of aberrant TCR-negative intraepithelial lymphocyte lines from refractory celiac disease type II patients

•TCR-negative IEL lines are derived from refractory celiac disease II patients.•Dendritic cells (DCs) induce proliferation and inhibit apoptosis of such RCDII lines.•DC-induced proliferation of RCDII lines is independent of IL-15 or HLA genotype.•IFNγ and CXCL10 is produced by cocultures of DC and RCDII lines.•DC may therefore contribute to uncontrolled expansion of RCDII cells in vivo.

Celiac disease (CD) patients who fail to respond to a gluten-free diet suffer from refractory celiac disease (RCD). A marked expansion of intraepithelial lymphocytes (IEL) lacking surface TCR/CD3 expression characterizes the RCD subtype II. In up to 50% of RCDII patients these so-called aberrant IEL (a-IEL) develop into lymphoma and can disseminate into other tissues. Elevated levels of Interleukin-15 (IL-15) in the intestine of CD and RCD patients likely contribute to the expansion of a-IEL. Here, we investigated if interactions with other cells might also influence a-IEL expansion. Similar to IL-15, cells from the monocyte lineage, particularly mature dendritic cells (DCs), promoted proliferation, prevented apoptosis and induced IFNγ secretion of a-IEL derived from RCDII biopsies (RCDII cell lines), which in turn induced CXCL10. In contrast to IL-15, mature DCs did not induce proliferation of regular TCR+IEL lines, generated from CD biopsies and IL-15-blocking antibodies did not inhibit DC-induced proliferation of RCDII cell lines. Furthermore, proliferation was dependent on cell-cell contact, but independent of the HLA-genotype of the stimulating cells. Our results suggest that contact with DC, either in the epithelium or upon dissemination, contributes to uncontrolled expansion of a-IEL in RCDII, independent of HLA-genotype and IL-15.