The results indicated that compared with arthritis mice (+ K/BxN serum −HFD), arthritis mice combined with atherosclerosis (+ K/BxN serum + HFD) had significantly increased amount of B1 cells (CD19+B220−) (P < 0.05), decreased number of mature B cells (CD19+B220+IgD+IgM+) (P < 0.05) in Peyer’ s patches as well as the number of Peyer’ s patches (P < 0.0001). The gene discussed is CD19; the disease is atherosclerosis.