Figure 5.

Anti-inflammatory innate memory response of human monocytes from one individual donor, primed with FeOxNP alone or together with LPS. Human monocytes isolated from blood of one individual donor (donor 4, diamond symbols); were cultured for 24 h in culture medium alone or containing serum-precoated FeOxNP (2 µg/ml FeOxNP 17 and 2.7 µg/ml FeOxNP 22) alone or together with 1 ng/ml LPS (line priming in abscissa). Cells were then washed and rested for 6 days in the absence of stimuli, then challenged for 24 h in fresh medium alone or containing 5 ng/mL LPS (m and LPS in the abscissa line challenge). The production of IL-10 (upper panel) and IL-1Ra (lower panel) was measured in the 24 h supernatants by ELISA (complete data shown in Figure 3). Horizontal dotted lines represent the reference values of cells primed with medium alone and cells primed with LPS in the two parts of each panel. The basal response of control cells (CTR), i.e., primed or unprimed cells rested for 6 days and then exposed for 24 h to medium alone, is shown at the extreme left in each panel (grey symbols). Data are reported as mean ± SD of replicate determination from individual donors out of four tested (all shown in Figure 3). Statistical significance is as follows. Upper panel: medium vs. LPS, p <0.05; medium vs. both FeOxNP, p <0.05; LPS vs. LPS + FeOxNP, p <0.05; FeOxNP 17 vs. LPS + FeOxNP 17, p <0.05. Lower panel: medium vs. FeOxNP 17, p <0.05; FeOxNP 17 vs. FeOxNP22, p <0.05. All other relevant comparisons are not significant.