BCG-polysaccharide nucleic acid and bacillus calmette-guerin decreased the incidence of asthma following infantile acute bronchiolitis

Objective To evaluate the effects of intervention by polysaccharide nucleic acid fraction of BCG(BCG-PSN),bacillus calmette-guerin (BCG) inoculation in preventing infants with acute bronchiolitis from asthma and explore its mechanism . Methods One hundred and twenty- eight infants with acute bronchiolitis were randomly divided into 3 groups: treated group A, treated group B and control group. BCG- PSN was administered to 43 patients in treated group A, BCG inoculation was administered to 45 patients in treated group B and the routine therapy was given to 40 patients in control group. Twenty healthy infants were used as the normal controls. The concentration of IFN- γ , IL-2, IL-4 and IL-10 from peripheral blood mononuclear cells, and the level of serum IgE were measured by using ELISA before treatment, 6 months after treatment and the patients aged 3 years old .The patients were followed- up for 2～ 2.5 years to count the incidence of asthma in children aged 3 years old. Results (1) IL- 4, IL-10 and IgE levels before treatment in treated group A, treated group B and control group were higher than those of the normal controls, but IFN- γ levels were lower than those of the normal controls with significant difference (P 0.01). (2)After 6 months of intervention both treated group A and treated group B, the levels of IL-4, IL-10 and IgE decreased significantly compared with those of before intervention; the levels of IFN-γ were significantly higher than those of before intervention. When the patients were 3 years old in treated group A and treated group B, there were no differences in the IFN- γ , IL-10 levels and higher levels of IL-4 and IgE compared with those of normal controls. (3)The incidence of asthma in children aged 3 years old in the treated group A and treated group B were significantly lower than those of the control group (P 0.005). Conclusion BCG- PSN and BCG may stimulate the production of IFN-γ in infants with acute bronchiolitis, down- regulate IL- 4 and IL- 10 levels, induce the dominant differentiation of Th1, and regulate Th1/Th2 balance. They can reduce the incidence of asthma after acute bronchiolitis.