Although no study has yet evaluated the action of IL-34 on the differentiation/function of T cells in IBD, it is noteworthy that IL-34-primed macrophages constitutively express membrane-type IL-1α, which stimulates differentiation of memory Th17 cells (54), a subset of CD4+ T cells that infiltrates massively inflamed gut in IBD and contributes to mucosal injury seen in mice with experimental colitis (55, 56). This evidence concerns the gene IL1A and inflammatory bowel disease.