Furthermore, there was a positive correlation between the percentages of Tfh and the expression level of OX40L on B cells in IgG4-RD patients (r = 0.528, p = 0.036), and the percentages of Tfh was positively correlated with the level of CD86 on B cells in HCs (r = 0.685, p = 0.007, Additional file 1: Fig. S6). The gene discussed is TNFSF4; the disease is immunoglobulin G4-related sclerosing disease.