The Studay About The Effects Of Bacillus Calmette-guerin On Activation And Apoptosis Of T Lymphocyte In Asthmatic Mice

ObjectiveTo observe the effects of bacillus calmette-guerin (BCG)treatment on expression of the costimulatory molecules of B7-CD28/CD152,the apoptosis protein of Fas/Bcl-2 and CD4⁺CD25⁺CD127^lo Treg, and the effect on T lymphocyte apoptosis in asthmatic mice and to explore the influencial factors of activation and apoptosis of T lymphocyte and to study the mechanism of about BCG's prevention and treatment for asthma .Methods27 mice were randomly divided into 3 groups,the asthma model group , the BCG treatment group and the control group . The mice were sensitized by ovalbumin and 10% AL(OH)3 with intraperitoneal injection,challenged by atomization inhalation ,then reproduced the asthma models. The BCG treatment group were treated 3 times with BCG subcutaneous injection before sensitization.The control group were treated with 0.9% saline water taking the place of ovalbumin and AL(OH)3. The expressions of CD28,CD152,CD80 and CD86 of splenic lymphocyte suspension were detected by flow cytometry . T lymphocytes were separated and cultured from peripheral blood mononuclear cell. The apoptosis ratio of T lymphocytes were counted by Comet Assay. The morphous of apoptosis T lymphocytes were observed with transmission electron microscope. The apoptosis protein of Fas/Bcl-2 in lung tissue were detected by immunohistochemical study. CD4⁺CD25⁺CD127^lo Treg in peripheral blood and PBMC were detected by triad colour immunofluorescence flow cytometry, PBMC were stimulated and cultured by PHA.Rusults 1.Compared the asthmatic group with the control group, CD28 and CD86 increased,CD152 and CD80 had no diversity. Compared the BCG treatment group with the asthmatic group, the expression of CD28 decreased.CD152 and CD80 were up regulated, CD86 had no difference between two groups.2.The apoptosis ratio of T lymphocyte was decreased remarkably in the asthmatic group than that in the control group. It was increased obviously in the BCG treatment group than that in the asthmatic group.3.Compared the asthmatic group with the control group, the apoptosis protein of Fas was down regulated; the apoptosis protein of Bcl-2 was up regulated. Compared the BCG treatment group with the asthmatic model group, the apoptosis protein of Fas was increased obviously , but Bcl-2 had no difference between two groups.4.Compared the asthmatic group with the control group, CD4⁺CD25⁺CD127^lo Treg decreased remarkably in peripheral blood and cultivated PBMC ;Compared the BCG treatment group with the asthmatic group, CD4⁺CD25⁺CD127^lo Treg increased obviously; CD4⁺CD25⁺CD127lTreg had no difference between peripheral blood and cultivated PBMC in asthmatic group, but that in normal group was more higher in cultivated PBMC than peripheral blood .5.All influential factors of T lymphocyte apoptosis were analyzed by multiple linear regression, we found that CD4⁺CD25⁺CD127^loTreg had a positive correlation with the apoptosis ratio of T lymphocyte,but CD28,Bcl-2 had a negative correlation with it.Conclusion1.In asthmatic mice, the expressions of CD28,CD86(B7-2 )increased, CD152 (CTLA-4) decreased, and CD80(B7-1) was invariant. After BCG treatment, CD152(CTLA-4), CD80(B7-1)was up regulated,CD28 was down regulated,CD86(B7-2) had no diversity; BCG promoted Th1 immune response.2.In asthmatic mice, the apoptosis protein of Fas decreased and Bcl-2 increased. After BCG treatment, Fas was up regulated and Bcl-2 had no difference.3.In asthmatic mice,the count of CD4⁺CD25⁺CD127^lo Treg decreased ,and there was a development disorder of CD4⁺CD25⁺CD127^lo Treg. After BCG treatment, the count of CD4⁺CD25⁺CD127^lo Treg was up regulated.4.The apoptosis or activation of T lymphocyte being induced by antigens depended on the balance of apoptosis factor and anti- apoptosis factor, such as B7-CD152, Fas, CD4⁺CD25⁺CD127^lo Treg versus B7-CD28,Bcl-2.5.There was a T lymphocyte apoptosis disorder in asthmatic mice. After BCG treatment , apoptosis factor increased and anti-apoptosis factor decreased, that promoted T lymphocyte to apoptosis.