CR2 and infection: There was also a decrease in the proportion of CD3–CD21+ B cells among splenocytes in the infection group compared to that in the control group (P < 0.001); levamisole, BMS-1 and 25–100 mg/kg baicalin enhanced the proportion of CD3–CD21+ B cells compared to that in the infection group (P < 0.001; Figure 6D, Additional file 5).