Change of CD4+ CD25+ regulatory T cells in asthmatic rat and the effect of dexamethasone on CD4+ CD25+T cells

Objective To investigate the change of CD4+ CD25+ T cells in bronchoalvelar lavage fluid (BALF), blood and spleen of asthmatic rat and the effect of dexamethasone on CD4 + CD25 + T cells.Methods Fifty SD rats were randomly divided into five groups with 10 rats in each group:control group (A), asthmatic group (B), dexamethasone low-dose group (C), dexamethasone mid-dose group (D),dexamethasone high-dose group (E). Group A was established by saline. The rat was injected saline 1 ml in 1 day and challenged from days 15 to 21 by saline 10 ml. The group B,C,D,E,were sensitized on days 1 by injected OVA 1mg and 1 % OVA aerosol challenged from days 15 to 21. The group C, D, E were injected dexamethasone(0. 2 mg/kg, 1 mg/kg,2 mg/kg) after challenges 30 minutes. CD4+ CD25+ T cells in BALF,blood and spleen are measured by flow cytometric analysis. Results BALF, blood and spleen's ratio of CD4+ CD25+ T cells to CD4+ T cells of group B were significantly higher than those in group A [(42.21±5.62)% vs (18.76±5.85)%, P ＜0. 01],[(12. 69±2.70)% vs (6.27±1.73)%, P＜0.01],[(11. 15± 1.05)% vs (7. 85±2.13)%, P ＜0.05]. In BALF, group C(10.49±4.03)%,group D (13.28±5.12)%, group E (7.51 ± 5.3)%, compared with group A (18.76 ±5.85)% group B (42.21± 5.62) %, the differences were significant ( all P ＜ 0. 05 ). In blood, group C ( 6.03 ± 1.43 ) %,group D(4. 88±0.95)%, compared with group A(6.21 ± 1.73)%, the differences were no significant.Group E( 3.49 ± 0.62 ) %, compared with group A ( 6.21 ± 1.73 ) %, group C ( 6.03 ± 1.43 ) %, the differences were significant, (allP ＜0.05). In spleen,group C (7. 25±1.82) % ,group D(8. 63±3.18) %,compared with group A (7.85 ± 2. 13) %, the differences were no significant. Group E ( 3.38 ± 1.37 ) %compared with group A ( 7.85 ± 2.13 ) %, group C ( 7.25 ± 1.82 ) %, group D ( 8. 63 ± 3.18 ) %, the differences were significant, ( P ＜0.05). Conclusions The ratio of CD4+ CD25+ T cells to CD4+ T cells of asthmatic rat exit predominance expression, which may be one of mechanisms of asthma pathogenesis.Dexamethasone can depress CD4+ CD25+ T cells predominance expression. The changes of CD4+ CD25+ T cells in BALF is consistent with that in the blood and spleen,which suggested that monitoring the changes of CD4+ CD25+ T cells in blood and spleen can be useful to understand the situatioan of BALF. Key words: Asthma; CD4+CD25+T cells; Dexametasone