Reduced interferon-gamma production in infants with bronchiolitis and asthma

Infants are at increased risk of developing asthma after acute bronchioliti s. We assessed the hypothesis that cytokine production is related to the de velopment of asthma after bronchiolitis. The smoking history and the presen ce of atopy or asthma in parents or siblings were recorded and blood mononu clear cell interferon (IFN)-gamma and interleukin (IL)-4 production in resp onse to IL-2 were assessed in 32 infants hospitalized for bronchiolitis and in a subgroup (n = 19) in which pulmonary function tests were performed ap proximately 4.9 mo later. The presence of asthma was determined by the Delp hi consensus method 2 yr after hospitalization. Infants were classified as follows: asthma absent (A, n = 14), possible (Po, n = 9), or probable (Pr, n = 9). Infants with possible and probable asthma had lower IFN-gamma produ ction at the time of bronchiolitis and a trend to lower IFN-gamma productio n 4.9 mo later when compared with those who had no asthma. At the time of b ronchiolitis, IFN-gamma production was: 123 +/- 31 versus 34 +/- 20 versus 21 +/- 14 pg/ml, A versus Po versus Pr (p = 0.02, ANOVA) and 4.9 mo after b ronchiolitis, IFN-gamma production was: 147.3 +/- 45 versus 47.4 +/- 30 ver sus 22.3 +/- 32 pg/ml, No versus Po versus Pr (p = 0.08 ANOVA). IL-4 produc tion did not differ between groups. Infants who went on to develop asthma h ad more parent smokers (21.4% versus 55.6% versus 55.6%, A versus Po versus Pr, p < 0.04), lower (V) over dot maxFRC (122 +/- 18 versus 77 +/- 7 versu s 67 +/- 8% predicted, A versus Po versus Pr, p < 0.02), lower PC40 histami ne (6.4 +/- 3.3 versus 1.2 +/- 0.6 mg/ml, A versus Po+Pr, p < 0.03) but no increase in atopy or asthma in their family. Significant positive correlati ons were found between IFN-gamma production at the time of bronchiolitis an d (V) over dot maxFRC (r = 0.606) or PC40 histamine (r = 0.648) 4.9 mo afte r bronchiolitis. Lower IFN-gamma production at the time of bronchiolitis is an indicator of lower pulmonary function and increased responsiveness to h istamine 4.9 mo after bronchiolitis and is related to the development of as thma after bronchiolitis in infants.