CD4 and inflammatory bowel disease: Other CD4 T-cell subsets include Foxp3- type 1 regulatory T (Tr1) cells, which secrete the suppressive cytokines IL-10 and TGF β [26,298], and Tfh cells, which are a specialized CD4 T-cell subset involved in the induction and differentiation of B cells into plasma cells and memory cells [299,300,301], cell subsets whose role in IBD has recently been reviewed [26,254,302,303].