Induction of IL-33 gene and protein expression in C57BL/6 lung tissue and BALF 30 days post-exposure to MWCNTs. Gene expression of IL-33 (A), determined by Real-Time PCR, demonstrated an approximate three-fold increase in left lung tissue of mice instilled with MWCNTs compared to vehicle control mice. Correspondingly, ELISA protein analysis (B) of IL-33 in BALF of mice exposed to MWCNTs was also significantly increased at all doses (1, 2, and 4 mg/kg) compared to vehicle control (10% surfactant in saline). All values are expressed as mean ± SEM (n = 6-11). #
p < 0.05 compared to vehicle control mice and ### p < 0.001 compared with the vehicle control mice.