Abstract: Low molecular weight heparin(LMWH), a newly developed biodrug, possesses multiple non-anticoagulant activities. Our results showed that LMWH at the concentrations of 16000and 8000 u·L^-1 could significantly (P<0.01, P<0.05 vs vehicle) inhibit constriction of isolated ileum smooth muscle of ovalbumin (OA)-sensitized guinea pigs induced by OA in vitro, LMWH 200, 50and 12.5 u·kg^-1 ip could markedly (P<0.01 vs vehicle) inhibit degranulation of pericranium MC in rats, LMWH 60 and 30 u·kg^-1 ip could significantly (P<0.01, P<0.05 vs vehicle) depress the licking response induced by 4-aminopridine and the increasing of capillary permeability induced by aceticacid in mice. These results indicated that LMWH in the dosages used in the present study possessed anti-allergic activity in several animal models, and the activity was related to its inhibitory effects on the degranulation of MC and to its anti-inflammatory effect.

Key words: Low molecular weight heparin, Anti-allergic effect, Mast cell