Objective: To investigate the effect and preliminary mechanism of formononetin on allergic inflammation. Method: Th2 Type allergic contact dermatitis (ACD) models were induced by fluoresciniso thiocyate (FITC). 35 BALB/c mice were randomly divided into normal group

model group

formononetin 0.5

5

10 mg·kg-1 groups(n=7). The mice were sensitized with 1.5%FITC solution on day 1 and day 2 on the shaved abdomen skin

once a day. On day 6

the mice were challenged on their right ears with 0.6%FITC solution. Formononetin was given to the mice from 2 days before sensitization to day 3 after sensitization

once a day for a total of 5 times (prophylactical administration in initial sensitization period);on day 6 of modeling

the mice were challenged on their right ears

and after 24 hours

ear swelling was observed and pathological changes of the ears were investigated by hematoxylin and eosin (HE) staining. The levels of interleukin-4 (IL-4)

IL-5 and IL-9 in homogenate of ear tissues were detected by enzyme-linked immunosorbent assay(ELISA). Result: As compared with the normal group

the ear swelling was significantly increased in mice of model group

with massive infiltration of lymphocytes (P < 0.01);dermis tissues of the ears had obvious edema;IL-4

IL-5 and IL-9 levels in the ear tissues were significantly increased (P < 0.01). As compared with the model group

prophylactical treatment with formononetin in initial sensitization period could significantly relieve the ear swelling and reduce lymphocytes infiltration (P < 0.05

P < 0.01)

reduce the histopathological changes of ears

and inhibited type 2 cytokines IL-5 and IL-9 levels in the ear tissues to different degrees(P < 0.05

P < 0.01). Conclusion: Formononetin evidently inhibited allergic inflammation at the initial stage of sensitization

and its mechanism might be associated with inhibiting the secretion of type 2 cytokines.