Fig. 4

Diesel exhaust particles alter T cell differentiation in vitro. Naïve CD4⁺ T cells were isolated from WT (C57BL/6 J) or Ahr^−/− mice. At time 0, cells were exposed to a dose-response (5 doses) of SRM1650b PM, SRM2975 PM, or PBS control and cultured for 3 days. a Representative flow plots of WT (top) and Ahr^−/− (bottom) Th17 differentiation at 12.5 μg/mL PM, measured by percent IL-17 positive cells. b SRM1650b PM enhanced Th17 differentiation at 12.5 μg/mL PM compared to PBS control and SRM2975 PM had no effect on Th17 differentiation (top). In Ahr^−/− cells, SRM1650b PM significantly increased % IL-17 positive cells at the two lowest doses. SRM2975 PM suppressed Th17 differentiation in Ahr^−/− cells at 40 μg/mL PM (bottom). c Representative flow plots of WT Treg differentiation at 20 μg/mL PM (top) and 0.78 μg/mL PM (bottom), measured by percent FOXP3 positive cells. d SRM1650b PM suppresses Treg differentiation at 40, 20, and 12.5 μg/mL PM and enhances Treg differentiation at 0.78 μg/mL PM (top). SRM2975 PM enhances Treg differentiation at 3.125 and 0.78 μg/mL PM (bottom). e Representative flow plots of WT (top) and Ahr^−/− (bottom) Th1 differentiation at 12.5 μg/mL PM, measured by percent IFNγ positive cells. f SRM1650b PM had no effect on Th1 differentiation in WT cells (top). SRM2975 PM enhanced Th1 differentiation at 40, 20, and 12.5 μg/mL PM (top). In Ahr^−/− cells, SRM1650b PM suppressed Th1 differentiation at 40 and 20 μg/mL PM but enhanced Th1 differentiation at 3.125 μg/ml PM (bottom). SRM2975 PM suppresses Th1 differentiation in Ahr^−/− cells at 40, 20, 12.5 μg/mL PM (bottom). Results are mean ± SEM of (WT Th17 n = 5), (Ahr^−/− Th17 n = 2), (WT Treg n = 2), (WT Th1 n = 5), and (Ahr^−/− Th1 n = 2). Significant differences among groups (p < 0.05) are indicated by an asterisk. Abbreviations: AHR, aryl hydrocarbon receptor; SRM, standard reference materials; PM, particulate matter; PBS, phosphate buffered saline