Intracellular expression of IFN-γ, IL-2, TNF-α, and IL-4 after stimulation of BAL CD4⁺ T cells with BeSO₄. (a) Staining patterns are shown for BAL cells from CBD patients 1, 2, and 3 after short-term culture with BeSO₄. The percentage of CD4⁺ T cells expressing the various Th1 and Th2 cytokines is shown in the upper right quadrant of each density plot. The expression of IL-4 after BeSO₄ exposure was not determined for CBD patient 3. (b) Flow cytometric analyses of TNF-α versus IFN-γ and IL-2 versus IFN-γ are shown for CD4⁺ T cells from CBD patient 2 following exposure to BeSO₄. The percentage of CD4⁺ T cells expressing both cytokines is shown in the upper right quadrant of the density plot.