Figure 1: Effect of DHEA on the adhesion induced by particles. Cells were treated with 1 (D1), 10 (D10), and 100 μM (D100) of DHEA alone or in combination with 10 μg/cm2 of TiO2 NPs (T) or 20 μg/cm2 of PM10 (P) for 24 h (a). After this, U937 cells labeled with [3H]-thymidine were cultured with HUVEC for 3 h more, and adhesion was evaluated in a scintillation counter. TNF-α (10 ng/mL) was used as a positive control. In (b), DHEA was added 1 h before (before), at the same time (same), and 1 h after (after) the addition of TiO2 NPs or PM10. The results were expressed as percentage of adhesion with respect to untreated cells (100%) and shown as mean ± SD of three separate experiments. compared with nontreated cells, and compared with particles-treated cells.