Figure 3. FcγR mediates inflammasome activation to enhance IL-1β.

(A) THP-1 were stimulated with iFt, mAb, or iFt-mAb for 23.5 h followed by treatment for 30 min with ATP (5 mM) before collection of cell-free culture supernatants for IL-1β or IL-18 by multiplex immunoassay. (B) Binding of GFP-iFt-mAb to THP-1 with or without FcγR blocking Abs as indicated by flow cytometry counting of cells labeled with GFP-iFt-mAb. The 1-dimensional histogram is 1 of 3 independent experiments with similar results. The filled curve is unstained cells, the solid curve is GFP-iFt-mAb without blocking Abs, the dashed curved is GFP-iFt-mAb with blocking Abs, and the dotted curve is GFP-iFt without mAb and without blocking Abs. THP-1 stimulated with iFt-mAb with and without FcγR blocking Abs were stained with Abs against mAbs (C). Green fluorescence indicates extracellular iFt-mAb; red fluorescence indicates intracellular iFt-mAb. Images were obtained by confocal microscopy. (D) Images are representative of 3 independent experiments with similar results. IL-1β and TNF-α from cell-free supernatants of THP-1 in the presence or absence of anti-FcγR blocking Abs. Shown are means of 3 independent experiments with error bars indicating sem. *P < 0.05; **P < 0.01; ***P < 0.001.