Several studies reported that Th17 cells can promote B cell activation and that the infiltrated Th17 cells in salivary glands of patients with SS were involved in promoting the generation of germinal centers [8–10]. In the present study, we compared the infiltrated B cells in the salivary glands of M3R/xIL-17/→ Rag1/ mice to M3R/→ Rag1/ mice with B cell infiltration. The salivary glands of M3R/xIL-17/→ Rag1/mice include few B220 cells and the number of infiltrating B cells in the salivary glands of M3R/xIL-17/→ Rag1/mice were significantly lower than in that of M3R/→ Rag1/ mice (Figure 1E, F). The majoring of infiltrated cells was CD4 T cells, similar to those seen in M3R/→ Rag1/ mice (Figure 1G). The titer of anti-M3R antibodies in the serum was not different between M3R/xIL-17/→ Rag1/ and M3R/→ Rag1/mice (data not shown). Judging from these results, we propose the following possibility that M3R autoreactive Th17 cells might activate infiltrated B cells in the salivary glands of MIS mouse.