Diminished IL-10 production has been documented in children and adults with asthma and atopy. Environmental tobacco smoke (ETS) is recognized as a risk factor for the development of childhood asthma. The purpose of this pilot study was to determine whether there is an association between ETS and DC IL-10 production during infancy.

ETS was assessed by questionnaire, and blood was obtained at 2 weeks, 3 months, and 5 months of age in 37 healthy infants. DCs were cultured and stimulated, and supernatants were assayed for IL-10 by EIA.

Sixteen infants had no history of TSE, and 21 infants had a history of TSE. The frequency of subjects with detectable IL-10 levels was similar in both groups at 2 weeks and 3 months, but significantly different at 5 months (p<0.001). In those without ETS, the frequency with detectable IL-10 levels increased during the observation period [25% at 2 weeks, 20% at 3 months, and 36% at 5 months (p<0.05 vs 2 weeks)]. In contrast, in those with ETS, the frequency with detectable IL-10 levels decreased during the observation period [33% at 2 weeks, 19% at 3 months (p<0.05 vs 2 weeks) and 7% at 5 months (p<0.001 vs 2 weeks)].

These results demonstrate an association between ETS and diminished DC-IL-10 production during infancy. Future studies need to expand upon these sample sizes and explore whether diminished DC IL-10 production is the mechanism by which ETS predisposes to the development of asthma/atopy.