Immunoregulation in infants with respiratory syncytial virus bronchiolitis

Respiratory syncytial virus (RSV) is the most important pathogen of the respiratory tract, and the most frequent cause of bronchiolitis in infants. The aim of the investigation was to determinate the pathomechanisms of bronchoopstruction and wheezing in RSV bronchiolitis in infants. We wanted to determinate the type of immunoreaction: it was classical Th1 or IgE (Th2) mediated reaction. Subjects and methods: 19 infants with RSV bronchiolitis and 9 healthy controls were being investigated. RSV was proved in nasopharyngeal secret by the method of rapid virus detection by monoclonal antibodies in the immunofluorescent test and/or was isolated in cell cultures. The blood samples were analysed within 6 days from the beginning of the disease. The control analyses were made 4-6 weeks later. The expression of CD23 and CD21 antigens on CD20 B lymphocytes was determinated by flow cytometry with the three-color immunofluorescent method. IgE and IgG4 RSV specific antibodies were determined by immunoblot, and total IgE by ELISA kit. Results. In 6 of 10 RSV positive infants the percentage of CD23 cells was significantly higher than in 9 RSV negative infants and in controls. Although in all RSV positive infants the IgE values were within the normal limits, in children with increased expression of CD23 antigen in acute period RSV specific IgE and IgG4 antibodies were detected. Conclusion. Our investigation confirms the hypothesis that in some infants RSV infection could provoke Th2 immunologic response. The investigation of CD23 expression on B lymphocytes in infants with RSV infection could be of prognostic value for later development of the bronchial asthma in this children.