Fig. 4.

Topical application of NM causes an increase in MPO activity and neutrophil infiltration in skin of SKH-1 hairless and C57BL/6 mice skin. Mice were exposed topically to either 200 µL of acetone alone or with NM (3.2 mg) in 200 µL acetone for 12–120 h and skin tissue was collected and frozen. MPO activity was determined in the skin samples using MPO fluorescence assay kit as detailed under materials and methods (A). Skin from exposed mice was also collected, processed, sectioned and subjected to MPO IHC as detailed under material and methods (B and C). NM-induced MPO activity in MPO IHC stained skin sections from SKH-1 hairless and C57BL/6 mice is shown in representative pictures (B and C), Data presented are mean ± SEM of three-five animals in each treatment group and samples were taken in duplicate for the MPO assay. Statistical significance of difference between the NM exposed and control groups were determined by one way ANOVA followed by Bonferroni t-test for pair wise multiple comparisons. *, p<0.001 as compared to control group. d, dermis; red arrows, MPO positive cells.