Cytokine Response Post Severe RSV Bronchiolitis Does Not influence Lung Function--Results From The RSV Bronchiolitis In Early Life (RBEL) Study

Abstract

1Background: Children who have severe RSV bronchiolitis as infants have an increased prevalence of asthma in childhood. The RBEL cohort did not show an overall increase in T helper 2 (Th ) cytokines (Interleukin (IL)-4 and 13) in children who were diagnosed with asthma by 2 age 6, but there was a notable reduction in lung function in those with asthma ( ). Castro M et al, J Allerg Clin Immunol 2008 Rationale: To compare cytokine levels (IL-2, 4, 13 and interferon-γ) at time of entry in the RBEL study and at age 6 years to lung function obtained at age 6 years in patients with severe RSV bronchiolitis. Methods: 206 infants hospitalized at St. Louis Children's Hospital with severe RSV bronchiolitis were enrolled in the RBEL cohort. Peripheral blood mononuclear cells were obtained at time of entry, and at 2, 4, and 6 years of age and were analyzed for IL-2, 4, 13 and interferon-γ by flow cytometry and real-time PCR. Spirometry before and after bronchodilator and methacholine bronchoprovocation challenge were performed at age 6 years. Results: There was an inverse relationship noted between FEV % predicted and interferon-γ levels at age 6 years in patients with definite 1 asthma (physician-diagnosis of asthma and PC <3.2 mg/mL) (n=26; Spearmann correlation coefficient=-0.5; p=0.0083). There was no 20 relationship between lung function at 6 years of age and the other studied cytokine levels obtained at time of entry in the group with definite asthma (all p>0.05). Conclusion: Following severe RSV bronchiolitis, children diagnosed with asthma do not have a Th dominant cytokine response in the 2 peripheral blood nor do cytokine responses appear to relate to subsequent lung function. Funded By: NIH HL61895, M01RR00036