Cytokine levels in lung tissue slices at 4 h and 24 h post-exposure to ENCF-1 and ENCF-4 PM (11 μg per 8 mm diameter slice). (A) IL-6, (B) TNF-α, and (C) MIP-2 concentrations in the conditioned medium (CM) from the lung tissue slices. Data are means ± SEM (n = 3 in each group). *p < 0.05 compared with CM-exposed negative control group from the same time point. #p < 0.05 compared with the ENCF-4 PM exposed group from the same time point. Lung slices exposed to 87 ng/mL of LPS served as a positive control.