Effect of ATRA on TF, TNF-α, and IL-8 protein expression in LPS-stimulated human monocytes. Freshly isolated human monocytes (1 × 10⁶ cells) were incubated with LPS alone, ATRA alone (10⁻⁵ mol/L) or with various doses of ATRA (1 × 10⁻⁹ to 1 × 10⁻⁵ mol/L) for 30 minutes before LPS stimulation (100 ng/mL). (A) Monocytes were incubated for 5 hours and TF antigen levels were measured by ELISA. (B) Monocytes were incubated for 24 hours and TNF-α antigen level in culture supernatants were measured by ELISA. (C) Monocytes were incubated for 24 hours and IL-8 antigen levels in culture supernatants were measured by ELISA. Results from three independent experiments (mean ± SE) are shown.