[Effects and mechanism of CD4+ CD25+ T cells on the airway inflammation of asthmatic mice].

Objective To investigate the effects and mechanism of CD+_4 CD+_ 25 T cells on the airway inflammation of asthmatic mice. Methods Sixty mice were divided into 3 groups (20 in each group) including group A [ovalbumin (OVA ) sensitized/challenged mice], group B (saline sensitized/challenged mice), group C [CD+_ 25 T cells deleted by anti-CD+_ 25 and OVA sensitized/challenged mice]. Mice of A group were sensitized on days 1 and 13 by OVA and challenged from days 21 to 29 by 2% OVA 10 ml repeatedly to establish a murine model of asthma characterized by airway inflammation. The mice of group B were treated by saline 10 ml. The mice of group C were treated by the same method of group A after deletion of the CD+_ 25 T cells by anti-mouse CD+_ 25 monoclonal antibody(McAb). Lymphocytes were separated from the spleen of the three groups and the number of T cells were calculated by Fluorescence Activated Cell Sorter (FACS). The CD+_4 T cells were purified and the expression of interleukin-10 (IL-10), transforming growth factor-β_1 (TGF-β_1) and cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) mRNA were analyzed by the method of reverse transcriptase-polymerase chain reaction (RT-PCR). The airway inflammatory indices were detected by hematoxylin and eosin(HE) staining. Results In repeatedly OVA-challenged mice (group A), the ratio of CD+_4 CD+_ 25 T cells to CD+_4 T cells decreased significantly [(3.10±0.03)%] as compared with group B [(9.60±0.04)%, P0.01]. The expression of IL-10, CTLA-4 mRNA and TGF-β_1 mRNA of OVA-challenged mice (group A) decreased significantly (0.250±0.040 vs 0.29±0.03, 0.28±0.06 vs 0.480±0.080, 0.47±0.05 vs 0.50±0.03, all P0.01). The expression of IL-10, CTLA-4 mRNA and TGF-β_1 mRNA of the mice treated by anti-CD+_ 25 McAb (group C) decreased as compared with groups A and B (0.080±0.020, 0.11±0.04, 0.12±0.05, P0.01). The inflammation in the lungs of mice with depleted CD+_4 CD+_ 25 T cells by anti-CD+_ 25 McAb was more marked than that in the OVA-challenged and control group mice. Conclusion The polarization of CD+_4 CD+_ 25 T cells in asthmatic mice decreased significantly, which may play an important role in the pathogenesis of asthma.