Abstract: Objective To explore the serum level of substance P and its clinical significance in patients with atopic dermatitis(AD).Methods The plasma level of substance P was measured by radioimmunoassay(RIA)in 35 patients with AD and 24 healthy controls.The correlation of substance P level with the disease severity[eczema area and index(EASI)score and Rajka scores]and eosinophil count was assessed.Results The plasma level of substance P was significantly higher in AD patients than that in normal controls(P<0.01),and positively correlated with the EASI score and Rajka score(r=0.95,0.86 respectively,both P<0.01).The eosinophil count in peripheral blood was also increased in AD patients as compared with that in the controls,and positively correlated with the EASI score and Rajka score(both r=0.42,P<0.05).A positive correlation was also found between the plasma level of substance P and eosinophil count in AD patients(r=0.43,P<0.05).Conclusion s Substance P may be a useful parameter in the evaluation of AD activity,and it may participate in the pathogenesis of AD by interacting with eosinophils.

Key words: Dermatitis,atopic, Substance P