Fig. 5.

BeO induces the expansion of antigen-specific T_reg cells that alter the functional capacity of Be-specific effector T cells. (A) Percentage of FoxP3-expressing CD4⁺ T cells in BAL of HLA-DP2 Tg mice exposed to one dose vs. seven doses of BeO is shown. (B) Frequency of Be-specific T cells in lung of HLA-DP2 Tg mice exposed to either one or seven doses of BeO using IL-2 ELISPOT is shown. Data are expressed as the mean spot-forming units (SFUs) per 5 × 10⁵ cells, and median values are indicated with solid lines. (C) Representative density plot of Be-loaded HLA-DP2–plexin A4 (DP2-PLXN4/Be) tetramer staining of BAL CD4⁺CD44⁺ T cells from a BeO-exposed HLA-DP2 Tg mice is shown. Gating on tetramer-binding CD4⁺CD44⁺ T cells, a substantial portion of the tetramer-binding T cells coexpress FoxP3. The gate for FoxP3 was set based on FoxP3 expression in CD4⁺CD44⁺ tetramer-negative T cells and applied to CD4⁺CD44⁺ tetramer-positive T cells. (D) Frequency of antigen-specific CD4⁺ T cells in BAL of HLA-DP2 Tg mice exposed to BeO with and without FoxP3 expression is shown. Median values are indicated with solid lines. Data represent a total of eight mice per group from two separate experiments.