Additionally, the CD86 expression on plasmablasts negatively correlated with fasting C-peptide (r = − 0.541, P = 0.009) and 2 h postprandial C-peptide (r = − 0.473, P = 0.047) (Fig. 3H), and positively correlated with IFN-γ+CD4+ T cell counts (r = 0.492, P = 0.017) in new-onset T1D subjects, whereas not with that of the overall CD4+ T cells (Fig. 3I). Here, CD86 is linked to type 1 diabetes mellitus.