HbS induces proinflammatory cytokine production by human monocytes. (A-C) mRNA expression (relative to β-actin and compared with control) of TNF-α (A), IL-1β (B), and IL-6 (C) by human monocytes from healthy blood donors (n = 6), in culture with HbS (20 μM), HbA (20 μM), or control, after 4 hours (n = 6 per group). (D-F) Levels of TNF-α (D), IL-1β (E), and IL-6 (F) in the cell culture supernatant of human monocytes from healthy blood donors (n = 4), in culture with HbS (20 μM), HbA (20 μM), or control, after 18 hours (n = 4 per group). (G-H) Levels of TNF-α in the cell culture supernatant of human monocytes from healthy blood donors (n = 3 to 6 per group), in culture with HbS or control, after 18 hours, at increasing HbS concentrations of 0.625, 1.25, 2.5, 5, 10, 20, 40, and 80 μM (G) and after increasing time of culture with HbS at a concentration of 20 μM (H). ∗∗∗P < .001; ∗∗P < .01; ∗P < .05 by one-way ANOVA. CTL, control; NS, nonsignificant.