| Objectives:Bronchial asthma is characterized by a chronic airway inflammation involving several cells particularly mast cells,eosinophils and T cells.But the pathogenosis is obscure.Till now T cell is considered to be the main reason for maintenance of airway inflammation in asthma.There exists an dysfunction of TH1/TH2 in allergic asthma.With the stimulation of all kinds of antigens,the establishing immune memory will switch to TH1 or TH2 phenotype.We hypothesised that if the genetic factors has little changes or the environmental factors emerge at the right period of tranformation of TH1/TH2, the physical transformation may be changed or be decorated.Furtherly we hypothese that if we inject some kind of antigens or avoid contacting one,we could maintain TH1 phenotype and reduce the possibility of allergy.Our experiment aims to demostrate wether differentkind of antigens such as house dust mite or BCG injection in newborn Wistar rats could affect airway inflammation by histologic,immunologic methods and by analyzing expression of IL-4mRNA in rats'airway.By all our experimental results we want to give the theoretical proves of vaccine use in asthma treatment and asthma prevention in early stage of life.Methods1. All Wistar rats were divided into four groups:HDM,BCG,positive control and negative control.In HDM, newborn rats were injected subcutaneously 0.1ml HDM one time per week (with the first injection at first day of life) totally four weeks.In BCG each newborn rat was injected subcutaneously with 0.1 ml BCG(containing 5×104CFU).And in the two groups left the injection is the same as HDM group but using N.S replacing HDM.From 31 days all rats were sensitized and chanllenged to induce asthma with OVA but in negative control group using N.S replacing OVA. 2. PBMC preparation and culture,ELISA for dectection of IL-4 and IFN-γ level in supernatants.3. ELISA for detection of plasma OVA specific IgE antibody.4. Bronchoalveolar lavage and detection of different cell types in BALF.5. Histological analysis of lung specimens by light-microscopy and electromicroscopy6. Detection of airway IL-4 mRNA expression by Situ-hybridization.Results 1. Different cell percentage detection in BALF of Wistar rats:mean BALF recovered volume >80%.Rats of positive control had a significantly higher percentage of BALF EOS number compared with the negative control.There were higher percentage of BALF EOS in HDM and lower percentage of BALF EOS in BCG compared with the positive control.2. Histological findings (1)with light microscopy there was no significant inflammatory changes of lung specimens in negative control;while in positive control and in HDM there presented a significant allergic inflammation,such as great number of eosinophils infiltrating into the airway and periairway, straitness of airway and airway embolism etc.In contrast,these changes in BCG were alleviated.(2)with electromicroscopy there were significant eosinophil infiltration in positive control.3. Detection of IL-4 in supernatants of PBMC:Rats in HDM had the highest level,while in BCG the lowest level.4. Detection of IFN-γ in supernatants of PBMC:Rats in BCG and negative control had higher level,while those in HDM and positive control had lower level.Detection of IL-4mRNA expression in lung specimens by5. site-hybridization:The percentage of cells expressing IL-4mRNA in positive control,BCG and HDM were 25.3±4.6%,9.2±3.9%,30.9±5.0%,respectively.In contrast,there was no IL-4mRNA expression in negative control.And there existed significant differences among each group.Conclusions1. Establishment of animal model of asthma rat and the significance in asthma research: In our research ,Wistar rats were sensitized and challenged successful with OVA plus Al(OH)3 as adjuvent,and also with intraperitoneal injection, subcutaneous injection and inhalation.The finding of significant inflammation,elevation of plasma OVA specific IgE level,higher level of IL-4 and lower level of IFN-γand...
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