This composite figure depicts a representative RNAse protection assay (left panel) demonstrating actinomycin D half-life of IL-10 transcripts in PBMNCs from an adult (upper gel) and from a term neonate (lower gel). Total cellular RNA was obtained at 10 hours of culture in the absence of stimuli (control) and in the presence of LPS (1 μg/mL). Following 10 hours of culture actinomycin D was added and RNA isolated at time 0, 15, 30, 60, and 90 minutes after its addition to the culture media. The RNA was subsequently hybridized to human IL-10 and β-actin probes. The right panel shows a linear regression analysis of IL-10 transcript half-life derived from unstimulated (C) and LPS-induced blood mononuclear cells of adult origin (n = 8) and of neonatal origin (n = 10) at various time points (0, 15, 30, 60, and 90 minutes) following addition of actinomycin D. Points representing mean of relative IL-10 transcript content (densitometric ratio of IL-10 to β-actin) plotted versus time are illustrated with adult values being represented by the closed circles, term values being represented by closed squares.