Fig. 2
Cell morphology and cytotoxicity of triple cell co-cultures exposed to volcanic ash and diesel exhaust particles. Confocal laser scanning microscopy (LSM) images show the complete triple cell co-culture (i.e. A549 type-II ‘like’ epithelial cell monolayer with human blood monocyte macrophages (MDM) and dendritic cells (MDDC) on the apical and basal sides, respectively) stained for F-actin cytoskeleton (red) and the nuclei (blue). a Control and cultures exposed to b 0.26 ± 0.09 μg/cm2 of single exposure to volcanic ash (SEVA), c 0.89 ± 0.29 μg/cm2, repeated exposure to volcanic ash (REVA), d diesel exhaust particles (DEP; 0.02 mg/mL), e diesel exhaust particles and 0.26 ± 0.09 μg/cm2 of single exposure to volcanic ash (DEP + SEVA), and f diesel exhaust particles and 0.89 ± 0.29 μg/cm2 of repeated exposure to volcanic ash (DEP + REVA). Yellow arrows indicate cells undergoing cell division. Scale bars are 20 μm (a-b) and 15 μm (c-f). Images were collected at magnification 63×. g Cytotoxicity determined by the release of lactate dehydrogenase (LDH) from the triple cell co-culture following exposure to SEVA, REVA, DEP, DEP + SEVA and DEP + REVA. Data are presented as fold increase relative to the negative control (supplemented cell culture medium only) ± standard error of the mean. Triton X-100 at 0.2% in phosphate buffered saline (PBS) acted as the positive assay control. LDH data shown are related to the following repetitions for each exposure: SEVA n = 4; REVA, DEP, DEP + SEVA and DEP + REVA n = 3; negative and positive controls n = 8