Increased annexin V staining of peripherally expanding T cells.

TXY/TCD C57BL/6 (Thy 1.2) mice were injected with 10 × 10⁶ congenic LN cells from B6 PL Thy-1a females (Thy 1.1). At 5, 11, and 21 days, mice were killed for flow cytometric analysis of apoptosis in Thy 1.1⁺ T cells. This figure is a representative histogram showing annexin V staining on Thy 1.1⁺ propidium iodide–negative splenocytes (gray line) at 11 days after an 18 hours incubation with concanavalin A compared to Thy 1.2⁺ splenocytes from thymus-bearing, T-cell–replete controls (black line) also incubated with con A for 18 hours. In a separate experiment there was no increased annexin V staining on Thy 1.2⁺ splenocytes from thymectomized T-cell–replete females when compared to sham thymectomized animals treated in the same manner (data not shown).