Rac1 regulates IL-1β release by MKD PBMCs. THP-1 cells were cultured for 24 hours in the presence or absence of simvastatin (20 μM) and stimulated for an additional 4 hours with 200 ng/mL of LPS. Rac1 inhibitor and PI3K inhibitor were added 1 hour before simvastatin treatment. Release of IL-1β (A) and caspase-1 p20 (B) was determined by ELISA; data are mean plus or minus SEM (n = 6 for control and PI3K inhibitor-treated samples, n = 3 for Rac1 inhibitor-treated samples, *P < .05). (C) Cell viability was determined by a lactic dehydrogenase assay (n = 3; *P < .05). (D) PBMCs of 3 healthy controls were cultured for 24 hours in the presence or absence of simvastatin (10 μM), followed by 24 hours of LPS stimulation (500 ng/mL). One hour before simvastatin treatment, the cells were incubated with the indicated concentrations of Rac inhibitor. Release of IL-1β was determined by ELISA; data are mean plus or minus SEM (n = 3). (E) PBMCs of 2 patients were cultured for 24 hours in the absence or presence of 500 ng/mL of LPS. Patient cells were incubated with 100 μM of Rac1 inhibitor 1 hour before LPS stimulation. Release of IL-1β was determined by ELISA; data are mean plus or minus SEM (n = 3, n = 2 for patient 2, *P < .05).