Figure 1.

T helper cells in bronchoalveolar lavage fluid: regulatory T cells, Th1, Th17, and IFN-γ ⁺ Th17 cells. Flow cytometry dot plots of bronchoalveolar lavage fluid CD4⁺ T cells gated by expression of FoxP3, IL17 (synonymous to IL-17A), and IFN-γ from a healthy control subject ((a)–(c)) and a patient with sarcoidosis ((d)–(f)). The T cell subsets are defined as follows: Th1 cells: IFN-γ ⁺ CD4⁺; Th17 cells: IL17⁺ CD4⁺; regulatory T cells: FoxP3⁺ CD4⁺ and IFN-γ ⁺; Th17 cells: IFN-γ ⁺ IL-17⁺ CD4⁺. Thus, the Th17 cells include the cells in both upper quadrants of plots (c) and (f). The patient and healthy control are representative examples. Gates for IL17 and IFN-γ were set according to unstimulated CD4⁺ T cells. Very few cells express intracellular IL-17 or IFN-γ prior to stimulation (median 0.0% in fractions of CD4⁺ T cells for both IL-17 and IFN-γ).