Fig. 2. Increasing UV irradiation increases caspase 3 cleavage and DNA decondensation.

a Human neutrophils were collected 2 h after activation with PMA (25 nM), A23 (4 µM) or increasing doses of UV. Immunoblots show that cleaved caspase 3 is found only in the UV conditions, and increase in UV doses increases caspase 3 cleavage (activation). Densitometry analysis confirms that caspase 3 cleavage dose-dependently increases following increased UV treatment (n = 3; *p < 0.05 for comparing with the negative control). b Neutrophils were treated with PMA (25 nM), A23 (4 µM) or varying doses of UV and incubated for 120 min. Cells were stained for DNA (DAPI, blue) and cleaved caspase 3 (red). Immunofluorescence imaging shows that cleaved caspase 3 is found in cells irradiated with UV light (scale bar, 10 μm). c Percentage of cells containing cleaved caspase 3 in cells treated with PMA (25 nM), A23 (4 µM) or varying doses of UV was calculated by counting cells immunostained for cleaved caspase 3 (n = 3; *p < 0.05 for comparing with the negative control). d Percentage of cells undergoing apoptosis, NETosis or neither (determined by nuclear morphology) in cells treated with PMA (25 nM), A23 (4 µM) or varying doses of UV was calculated by counting cells stained for DNA after 240 min (n = 3, *p < 0.05 for comparing percentage undergoing NETosis to percentage undergoing apoptosis within each treatment). Images are representative of three independent experiments. Error bars represent SEM; A23, A23187. See low-magnification images in Fig. S4