OBJECTIVETo investigate the expression of T-bet mRNA in peripheral blood mononuclear cells (PBMC) as well as its relations with total IgE (TIgE), eosinophil cationic protein (ECP) in serum and nasal allergic symptoms in patients with allergic rhinitis (AR).

METHODSThe allergen, TIgE and ECP in serum of patients with AR were detected by Unicap CAP system. Blood sample was taken from 8 healthy individuals and 22 patients with allergic rhinitis. PBMC was isolated by density gradient centrifugation and one part of them was cultured with 50 microg/ml mite allergen. PBMC was subjected to analysis of T-bet mRNA expression using semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTSThe ratio of T-bet to beta-actin mRNA levels was 0.381 +/- 0.099 in patients and 0.750 +/- 0.067 in normal individuals, the difference was significantly (P <0.01). The expression intensity of T-bet mRNA had no relation to varying severity of allergic symptoms and concentration of ECP and the correlation coefficient was 0.187 and -0.165 (all P > 0.05). However, there was an inverse correlation between expression intensity of T-bet mRNA and TIgE concentration (r = -0.525, P < 0.05). Mean mRNA level (x +/- s) of T-bet expression before and after being stimulated by allergen was 0.381 +/- 0.099 and 0.365 +/- 0.104 respectively, which indicated no significant differences (P > 0.05).

CONCLUSIONSAmong allergic patients whose allergen was mite, there was a down-regulated expression of T-bet mRNA, which had no relation to ECP concentration and allergic symptoms, but was one of important links in mechanisms of imbalance of Th1/Th2 in AR. There was no effect of specific allergen on T-bet mRNA in patients with AR T-bet was one of indirect factors that affected the level of IgE.