Fig. 7. Physical properties of IL-1 secretion. (A) Stills from a bright-field movie sequence of LPS-treated (1 µg/ml, 2 hours) murine macrophages stimulated with ATP (5 mM) in the absence (i) and presence (ii) of the caspase-1 inhibitor Ac-YVAD-fmk (50 µM). Time in minutes (min) after the addition of ATP is indicated. Arrows indicate blebbing cells. Bar, 10 µm. (B) The effects of ATP and Ac-YVAD-fmk in the above movies were quantified, with cells classified as dormant (white bars), alive but not blebbing (black bars), and alive and blebbing (gray bars). Data are the mean ± s.d. of cells counted from three independent experiments. (C) The effects of cholesterol depletion using -MCD (7.5 mM, 30 minutes) on cell death (LDH release, left y-axis) and IL-1 release (right y-axis) from LPS-treated (1 µg/ml, 2 hours) murine macrophages in the absence or presence of ATP (5 mM, 10 minutes). -MCD-treated cells, white bars; control cells, black bars. Data are the mean ± s.d. of duplicate wells from three independent cultures.