Figure 2.

Cystine crystal–induced IL-1β secretion requires caspase-1 activation, actin polymerization, lysosomal protease activity, ROS generation, and potassium efflux. PBMCs were primed with LPS (100 ng/ml) for 2 hours, incubated for 30 minutes in the presence or absence of (A) the CASP-1 inhibitor z-YVAD-fmk (5 μM) or phagocytosis inhibitor cytochalasin D (5 μM) or (B) cathepsin B inhibitor CA-074Me (10 μM) or diphenyleneiodonium chloride (DPI) (20 μM) or 130mM KCl. Cystine crystals or monosodium urate crystals (MSU) were added for 6 hours. Supernatants were collected and IL-1β was measured by ELISA. Data are representative of three independent experiments performed in duplicate and are expressed as means±SD. *P<0.05 compared with cells stimulated in the absence of inhibitors.