Enhanced IL-4 responses in children with a history of respiratory syncytial virus bronchiolitis in infancy.
Infants who recover from respiratory syncytial virus (RSV)-induced bronchiolitis are at high risk of developing asthma and recurrent wheezing. It is not known whether severe RSV infection itself causes persistent effects or is a marker of a "wheezy" predisposition. To determine the long-term immunological correlates of infantile bronchiolitis, interleukin (IL)-4 and interferon (IFN)-gamma responses to a panel of antigens were studied in a well-characterised cohort of 7-8-yr-old children with a history of severe RSV bronchiolitis in infancy. Peripheral blood lymphocytes from 37 children who were hospitalised with RSV bronchiolitis in infancy and from 69 age-, sex- and location-matched controls were stimulated in vitro with RSV, house-dust mite, birch and cat antigens. Cellular proliferation, and enzyme-linked immunoSPOT IFN-gamma and IL-4 production were measured. IL-4 producing T-cells responding to RSV and cat antigens were significantly more frequent in exbronchiolitics. Other responses (including the IFN-gamma response to RSV) were equally strong in exbronchiolitics and controls. Respiratory syncytial virus infection primes memory T-cells that make interferon-gamma, but virus and aeroallergen-specific and interleukin-4 producing T-cells are also frequently primed in bronchiolitics. Respiratory syncytial virus bronchiolitis in infancy may increase the risk of allergic sensitisation by providing a local interleukin-4-rich environment, in which airborne allergens are first encountered.
Pala
P
P
Dept of Respiratory Medicine, National Heart and Lung Institute, Imperial College of Science, Technology and Medicine, London, UK. p.pala@ic.ac.uk
Bjarnason
R
R
Sigurbergsson
F
F
Metcalfe
C
C
Sigurs
N
N
Openshaw
P J M
PJ
D001249:Asthma / Q000209:etiology* / Q000276:immunology*; D001990:Bronchiolitis, Viral / Q000150:complications* / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007223:Infant; D007371:Interferon-gamma / Q000032:analysis / Q000276:immunology*; D015847:Interleukin-4 / Q000032:analysis / Q000276:immunology*; D008297:Male; D012135:Respiratory Sounds / Q000209:etiology* / Q000276:immunology*; D018357:Respiratory Syncytial Virus Infections / Q000150:complications* / Q000276:immunology*; D012136:Respiratory Syncytial Viruses / Q000472:pathogenicity*; D012307:Risk Factors; D012720:Severity of Illness Index; D013997:Time Factors
D015847:Interleukin-4; D007371:Interferon-gamma