Abstract： Objective To investigate the mRNA expression of Fc gamma RⅡA(FcγR ⅡA)on polymorphonuclear neutrophils(PMN)from patients with Beh(c)et's disease(BD).Methods Twenty-five patients with active BD and 20 healthy human controls were included in this study.Blood samples were obtained from all patients with active BD before treatment,from 15 patients with inactive BD after treatment and from healthy controls.PMN were isolated.The FcγR Ⅱ A mRNA expression on PMNs was detected by RT-PCR,and plasma myeloperoxidase (MPO)activity which represented neutrophil activation,was measured spectrophotometricaily.Results The relative expression level of FcγR Ⅱ A on PMN and plasma MPO aetivity were 1.80 1±0.829 and 32±5 U/L.respectively,in patients with active BD,0.820±0.625 and 27±4 U/L,respectively,in those with inactive BD,and 0.745 ±0.931 and 29±5 U/L,respectively,in normal controls;the differences were significant in the two parameters between the patients with active and inactive BD (both P＜0.01),while no statistical difference was observed between inactive patients and normal human controls(P＞0.05).There was a positive eorrelation between the expression level of FcγR Ⅱ A on PMN and plasma MPO activity in patients with BD(r=0.39,P＜0.0 1).Conclusions The mRNA expression of FcγR ⅡA on neutrophils is up-regulated in patients with active BD.It is likely that FcγR Ⅱ A is involved in the activation of neutrophils in BD.