| BackgroundRespiratory Syncytial Virus (RSV) bronchiolitis is one of the mostfrequent lower respiratory infections for infants less than one year old. So far, its effective immune prevention or specific treatment is still absent due to the lack of understanding of its pathogenesis and immunopathological changes. Some infants with RSV bronchiolitis later suffer from recurrent wheezing, and one third of them will get asthma. The morbidity rate for atopic infants will be over 50%. The pathogenesis of asthma is commonly believed to be related to the TH1/TH2 unbalance and TH2-predominant response. Because of the close relationship between RSV bronchiolitis and asthma, we have reasons to assume that TH2-predominant response and strong local type II cytokine response also exist in the case of RSV bronchiolitis. Chinese and overseasresearches had focused on the cytokine response types of RSV-infected persons by testing the cytokines of serum or in supernatant of peripheral blood cultured, or by testing the functional status of single lymphocyte. Such indirect inference of the types of local cytokines response involves many mixing factors and leads to divergent conclusions. Moreover, there has been little coverage about research on local cytokines. Aimwe tested and analyzed the levels of IL-4, IL-12 and IFN-y in nasopharyngeal aspirate (NPA) of infants infected with RSV bronchiolitis, with the aim to explore the types of cytokines of RSV bronchiolitis from the perspective of local cytokine changes. MethodsTwenty-eight RSV bronchiolitis cases at acute stage (9 severe cases and 19 mild cases, 7 atopic cases and 21 nonatopic cases), 13 non-RSV bronchiolitis cases, 22 non-RSV pneumonia and 13 control cases were analyzed. Twenty convalescent cases of RSV bronchiolitis were also enrolled.After hospitalization, aerosol inhalation spray of 5.0ml 0.9% NS was applied on all research subjects and then disposable sputum collector used to get samples from the subjects (nasopharyngeal aspirates.NPA)RSV antigen in the epithelial cells of respiratory tracts of bronchiolitis/pneumonia infants was detected with direct immunofluorescence technique (Chemicon kit, USA)Levels of IL-4, IL-12 and IFN-γ in NPA were determined by solid sandwich ELISA technique using kits from DIACLONE research company, France. Results1. There existed great differences in IL-4, IFN-γ and IL-4/ IFN-γ ratio among RSV bronchiolitis, non-RSV bronchiolitis, pneumonia group and controls(F= 7.194, 8.056, 13.381, P<0.01)The level of IFN-γ in the group of RSV bronchiolitis (139.03±82.33ng/L) at acute stage was much lower than non-RSV bronchiolitis(272.61±107.55ng/L), pneumonia group(260.62±150.40 ng/L) and control (267.35±93.12 ng/L) ], with a clear difference (P<0.01) The level of IL-4 and IL-4/ IFN-γ ratio were clearly higher in RSV bronchiolitis group at acute stage (7.06±4.29ng/L,0.061 ±0.044) than non-RSV bronchiolitis(3.55±1.71ng/L,0.015±0.009) , pneumonia group (3.43±2.17ng/L, 0.019± 0.017) and control (4.03±2.55ng/L,0.015±0.008) (P<0.01). IL-12 levels in NPA were much higher in non-RSV bronchiolitis (1438.47±973.42ng/L) and pneumonia group (1252.29±840.29ng/L) than RSV bronchiolitis group(559.23±336.04 ng/L) and the control (608.70±109.41ng/L) (P<0.01) . A comparison between the latter two groups showed no statistical difference(P>0.05);2. The IL-4 level in the NPA of RSV bronchiolitis at acute stage was higher than the convalescent phase (3.47±2.79ng/L) (P<0.01). The IFN-γ level was lower than convalescent phase (261.54±166.13ng/L) (P<0.01) ,with IL-4/IFN-γ ratio increased significantly (P<0.01) [acute stage (0.061 ±0.044) vs.convalescent phase (0.014±0.006) ]. No statistical differences were found in NPA IL-12 levels among acute phase, convalesent phase and control (P>0.05) .3. There was no statistical difference in the IL-4 and IFN-γ levels in NPA between mild RSV bronchiolitis (6.34±4.81ng/L, 156.26±85.99ng/L) and controls (P>0.05) , but the former had a higher IL-4/IFN-γ ratio (0.042±0.034) than contr... |
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