Fig. 4

MWCNT High-COOH nanoparticles induce mast cell/ basophil degranulation in skin. Mice were sensitized with 30ul 0.05% DNFB in a 4:1 acetone/olive oil vehicle on the abdomen on day 0. On day 5 the mice were collared to prevent grooming and challenged with 50 μl of either vehicle (a), 5 μg MWCNT (b), 0.2% DNFB (c), or 0.2% DNFB with 5 μg MWCNT (d) on a 5 cm² area of dorsal skin for 24 h. Skin was fixed in 10% formalin, paraffin embedded, and stained with toluidine blue to assess the number of degranulating mast cells/basophils. Representative images of toluidine blue stained samples are included, and black arrows indicate degranulating mast cells. The total number of mast cells/ basophils (e) and the percentage of degranulating mast cells/ basophils (f) are quantified. The graphs represent the mean (+/− SEM), N = 6. Significance is defined at a p-value < 0.05. * indicates significance compared to control, # indicate significance within groups