IFN-α production is inhibited in neonates. (A) Induction of IFN-α release in whole blood by CpG 2216. Adult and cord blood samples were cultured with graded doses of CpG 2216 or control ODNs. After 20 hours, plasma samples were assayed by ELISA for detection of IFN-α levels. Shown is 1 representative experiment out of 3. (B) IFN-α production by enriched pDCs upon stimulation with CpG 2216. Adult and neonatal enriched pDCs were cultured with 10 μg/mL CpG 2216 or control ODNs. After 48 hours, supernatants were assayed by ELISA for detection of IFN-α levels. The figure shows medians (25th-75th quantiles) of 6 adult samples and 6 cord blood samples. ^*P < .05. (C) Determination of IFN-α mRNA levels by real-time PCR. Whole blood (1 mL) was incubated in the absence or presence of 50 μg CpG 2216. After 20 hours, mRNA was extracted, reverse transcribed, and amplified by real-time PCR using primers specific for IFN-α and β-actin. IFN-α mRNA levels were quantified and normalized against β-actin levels. The figure shows individual values and medians of 7 adult samples, 10 cord blood samples, and 8 blood samples from 4-day-old babies.