Before three days of finishing administration, all the mice were immunized intraperitoneally with 0.2 mL of 5% (v/v) SRBC. On 9th day, after measuring the left footpad thickness, the mice were again challenged with 20 μL of 20% (v/v) SRBC in another paw. The increase footpad thickness was considered as foot swelling (in mm) after 24 h.