The recent analyses of the CD4 CD26-high T cell subset showed that it is composed of Th1, Th17 and hybrid Th1/Th17 cells, all capable of transendothelial migration [76,77,78,79] and related to clinical severity in multiple sclerosis [80] and rheumatoid arthritis [67,68]. This evidence concerns the gene DPP4 and multiple sclerosis.