Upregulation of KIR3DL1 gene expression in intestinal mucosa in active celiac disease

Killer cell immunoglobulin-like receptors (KIRs) modulate natural killer (NK) and T-cell function by human leukocyte antigen class I interaction and have been implicated in celiac disease (CD). Qualitative expression of 16 KIR genes was determined in biopsies from 22 CD patients at diagnosis and after >2 years on a gluten-free diet (GFD). Quantitative expression analysis of KIR2DL4, KIR3DL1, KIR3DL3, and KLRC2 (a marker of an NK-reprogrammed T-cell subpopulation augmented in CD) was performed in 35 additional CD biopsy pairs and 14 non-CD control biopsies. No specific KIR expression profile was observed in CD. KIR3DL1 was more frequently expressed in active CD compared with GFD (p = 0.0312) and controls (p = 0.0008), with slightly increased levels in active disease. KLRC2 was overexpressed in active (p = 0.0037) and GFD (p = 0.0469) patients compared with non-CD controls and coexpressed with KIR3DL1. Results suggest the participation of KIR3DL1 overexpression in the overall immune activation seen in CD mucosa, which could be partly explained by the NK-like T-cell subpopulation increase.