(A) Monocytes were preincubated or not with β-glucan and differentiated with either GM-CSF or M-CSF. The resulting macrophages were primed for 3 hours with LPS and then stimulated for 1 hour with nigericin or vehicle as a control. Caspase-1 (pro form and cleaved p20), NLRP3, ASC, and IL-1β (pro form and mature IL-1β) expression was assessed by Western blotting. Mature IL-1β and the p20 fragment of caspase-1 were also detected in cell culture supernatants. β-Actin was used as the loading control. Blots are representative of 5 independent experiments. (B) Densitometric analysis of the blots shown in A. Immunoreactive bands in cell lysates were normalized to β-actin. (C) Densitometric analysis of the blots done on supernatants shown in A. Data represent the mean ± SEM of the analysis of 4 independent experiments. n = 5. *P < 0.05, by Wilcoxon matched-pairs, signed-rank test. casp-1, caspase 1.