Male and female C57BL/6 mice were exposed to cSiO2 (1 mg), MWCNTs (50μg), or dispersion media (DM) vehicle control (50 μl), once per week for 4 weeks and harvested 8 weeks after the last exposure. Whole lung lavage fluid (LLF) was collected for total cell counts (A), extracellular protein assessment (B), and cytometric analysis of immune cell populations within the airspace (C, D). The frequency of specific immune populations expressed as a percentage of all non- and immune-related cell types; data represented as mean ± SEM, n = 4–5. * p < .05, ** p < .01, *** p < .001, **** p < .0001 compared to same-sex DM control, # compared to males of the same treatment. IM/Mo, interstitial macrophage/monocytes; MFI, median fluorescence intensity.