Figure 10.

TCDD-mediated AHR activation significantly induced PD-1 protein expression in CD5⁺ ILB by days 2- and 3-post activation and is reduced by treatment with AHR antagonist, CH223191. Human CD5^+/- B cells were isolated from human PBMC as previously described. Cells were then treated with either DMSO, 10 μM CH223191, 10 nM TCDD, or TCDD plus antagonist, and activated as described for 7 days. Cells were collected on days 2 and 3 post-activation for quantification of cell surface PD-1 protein levels. Representative flow plots from each time point/treatment/cell type are shown in panels (A, D). Averaged raw percentage expression of PD-1 within gated CD19⁺ B cells are shown in panels (B, E) with data normalized to the respective vehicle controls shown in panels (C, F). Cells were also collected at day 7 post-activation for functional analysis by IgM ELISPOT. Representative select ELISPOT wells are shown in panel (G). Averaged raw IgM spots per million cells are shown for each cell type and treatment group in panel (H) and spots normalized to each respective vehicle control are shown in panel (I). Data are from 4 independent experiments assessing a total of 8 human donors. Significance was determined using a two-way, repeated measures, ANOVA with a Tukey’s posttest. *p < 0.05.