High level of monocyte cytokine response to PRR stimulation decreased between 6 and 12 months of age.

<p>Whole blood samples from neonate-infant subjects were followed longitudinally from 2 weeks (2 wk; n = 28), 6 weeks (6 wk; n = 26), 6 months (6 mo; n = 23) and 12 months (12 mo; n = 20) of life, and 10 adults (Ad) were stimulated with the indicated TLR ligands for 6 h, and intracellular cytokine levels were measured by flow cytometry for TNF-α, IL-6 and IL12/23p40 gated on monocytes. For each cell type, the total percentage of cytokine-producing cells is represented by the overall height of bar graphs; color-coded segments constituting the bar allow differentiation of cells producing various cytokine combinations. Unstimulated samples displayed cytokine production at near 0% and were subtracted from the stimulated samples. (<b>A</b>) Overall stacked bar graph; statistically significant differences in percent responders are indicated by p-value *<0.05. Cytokine profile – color combinations indicated in inset in identical order as in bar graphs from top to bottom. (<b>B</b>) Line graphs indicate polyfunctionality degree (PFD) for monocytes, summarizing the percentage of cells producing 1 (PFD1), 2 (PFD2), or 3 (PFD3) cytokines for each age group.