Similar to the results from SLE and pemphigus patients (Fig. 2), both activation markers (HLA-DR, IgG and IgM) and costimulatory molecules (including ICAM-1, CD40, ICOSL and OX40L) exhibited higher expression patterns on CD19hi B cells when compared to CD19lo counterparts (Fig. 3d), even more dramatically than those from SLE and pemphigus patients. Here, CD40 is linked to systemic lupus erythematosus.