1Maha Y. Zein El-Abedin, 2Zeinab N. Said, 2Magda A. Gameel and 3Intesar El-Sayed
1Pediatrics, 2Microbiology and 3Chest Departments Faculty of Medicine (for Girls), Al-Azhar University, Cairo Egypt.
Respiratory syncytial virus (RSV) infection represents the
most common cause of bronchiolitis and severe wheezing in infancy and early
childhood and has been linked to the development of chronic airway disease. It
is not known what differentiates the patients who recover completely from
wheezes from those who go on to develop asthma afterwards. This study
investigates IFN-g, IL-4 and IL-12
responses in infants with RSV-bronchiolitis to explore whether cytokine levels
influence the course of RSV bronchiolitis. Thirty-four infants with acute
bronchiolitis and 10 control infants were enrolled in this study. RSV-IgM was
detected by immunofluorescent technique in 25/34 patients. The cytokine pattern
was analyzed in relation to RSV-bronchiolitis. Significant decrease in serum
interferon-γ level was found
in infants with acute bronchiolitis as compared to controls (p < 0.01), and
in RSV-IgM positive versus negative patients (p<0.05). This decrease was
associated with nonsignificant increase in IL-4 and IL-12 serum levels
(p>0.05). Majority of these patients (30/34) presented with severe symptoms.
Certain host factors have been associated with severe illness as low
socioeconomic status, exposure to passive tobacco smoking and positive family
history of asthma. Prolonged course of illness was associated with severe drop
in serum level of IFN-g and IFN-g/IL-4 ratio and significant increase in
IL-12. In conclusion, the marked reduction of serum IFN-g despite the significant increased IL-12 level in patients with
prolonged course of illness raises the possibility of an intrinsic defect in
IFN-g that could be related to atopic
liability in those patients.