Figure 3.

Expression level of Noxa controls the generation of memory Th2 cells. (A) Enforced expression of Noxa-induced cell death in effector Th2 cells after cytokine depletion. Effector Th2 cells infected with a Noxa-IRES-hNGFR–containing retrovirus were cultured in vitro for 24 h without cytokines. hNGFR profiles (left) and annexin V staining profiles of the electronically gated hNGFR⁺ (gate #2) and hNGFR⁻ (gate #1) populations are shown. Three independent experiments were performed with similar results. (B) KJ1⁺ effector Th2 cells infected with Noxa-IRES-EGFP–containing retrovirus were transferred into BALB/c nu/nu mice. 5 wk later, memory Th2 cell generation was determined by KJ1/EGFP expression. Expression of EGFP in pretransferred effector Th2 cells (top left) and a typical KJ1/GFP profile of freshly prepared memory Th2 cells (top right) are shown. In the bottom panels, the percentages of KJ1⁺ cells and GFP⁺ Noxa-overexpressing cells and the mean fluorescence intensity of the GFP⁺ cells are shown with standard deviations (n = 4). The experiments were performed twice with similar results. (C) The effector Th2 cells from Bmi1^+/+/Noxa^+/+, Bmi1^+/−/Noxa^+/+, and Bmi1^+/−/Noxa^−/− mice (Ly5.2) were transferred into Ly5.1 host mice, and the number of Ly5.2⁺ memory Th2 cells was determined. A typical staining pattern of CD4/Ly5.2 (top) and the percentages of Ly5.2⁺ cells among CD4 T cells are shown with standard deviations (n = 5; bottom). Three independent experiments were performed with similar results. (D) Deletion of the Noxa gene enhanced the generation of memory Th2 cells. In vitro–generated Noxa^−/− effector Th2 cells (Ly5.2) were transferred into Ly5.1 host mice. 5 wk after cell transfer, the number of Ly5.2⁺ memory Th2 cells was determined. A representative CD4/Ly5.2 profile (left) and the mean values with standard deviations (n = 5; right) are shown. The experiments were performed twice with similar results.