(A) Serum levels of IL-6 in CpG-ODN-injected mice were significantly higher compared with control mice. *P<0.05. CpG-ODN stimulation increased production of IL-6 of splenocytes of ddY mice in culture. Incubation of splenocytes of ddY mice with recombinant IL-6 increased production of total IgA and aberrantly glycosylated IgA, resulting in the formation of IgG-IgA IC. Recombinant IL-6 increased overproduction of APRIL. Bars represent the mean±SEM. **P<0.01. (B) Splenocytes in culture were stimulated with CpG-ODN in the presence or absence of IL-6-neutralizing antibody. Anti-IL-6 antibody reduced production of total IgA and aberrantly glycosylated IgA, and, consequently, reduced formation of IgG-IgA IC induced by CpG-ODN. **P<0.01. PBS, Phosphate-buffered saline.