When assessed on day 7, the T cells of patients with AIH had, on average, a higher proliferative response compared with individuals in the control groups, as demonstrated by a higher frequency of CFSEloCD25+ICOS+ cells, but SepSecSpp-induced T cell proliferation was also detected in some of the individuals in the PC and HC groups (Figure 4, A and B). Here, ICOS is linked to autoimmune hepatitis.