Importantly, a recent paper employing HLA class II tetramers to directly characterise gluten-specific T cells in the blood and gut of individuals with coeliac disease demonstrated that the pathogenic antigen-specific T cells in coeliac disease also have a CXCR5−PD-1hi phenotype with high expression levels of IL-21 and CXCL13 transcripts, highly reminiscent of Tph cells [15]. This evidence concerns the gene IL21 and celiac disease.