Figure 4.

Effect of maturation and priming with low and high β-glucan dosages on proinflammatory responses of murine brain microglia. Microglia isolated from newborn (orange dots, open columns), adult (green dots, hatched columns), and aged (blue dots, gray columns) mice were primed initially by ultra-low (ULP, 100 fg/ml) or high (HP, 1 μg/ml) doses of β-glucan, followed by a second stimulation (day 6) with 100 ng/ml LPS. The data were normalized and compared to unprimed microglia (UP Group without any stimulation at day 1 with stimulation at day 6 with fixed dose of LPS 100 ng/ml). Unstimulated microglia served as negative control (US Group without β-glucan stimulation neither at day 1 nor at day 6). Supernatants were collected 24 h after the 2nd stimulation and analyzed for TNFα (A) (n = 4–8) and IL-6 (B) (n = 5–8) levels by ELISA (normalized to total protein concentration). Data shown in scatter dot plots represent means + SEM, ^#p < 0.05 vs. unprimed conditions within each age group (naïve or mature), ^§p < 0.05 vs. adult microglia within each stimulation condition (US, UP, ULP, HP).