FIG. 2.

TGF-β promotes the survival of previously activated autoreactive CD8⁺ T-cells by decreasing their apoptosis. A: Apoptosis was evaluated by TUNEL in pancreatic tissue sections obtained from mice fed a doxycycline (dox)-free diet (top panels). Cell suspensions were prepared from the pooled pancreatic draining lymph nodes of three to four mice and stained with H2-l^d/NP118 tetramers and annexin V (bottom panels). Histograms show the frequency of tetramer-positive CD8⁺ T-cells stained with annexin V. B: CD8⁺ T-cells were purified from the spleen of LCMV-immune BALB/c mice, labeled with CFSE, and cultured with LCMV-infected, irradiated, antigen-presenting cells in the presence or absence of 3 ng/ml rhTGF-β1. Cell proliferation was assessed by measuring CFSE dilution by flow cytometry after 6 days in culture (top panel) or cell cycle protein RNA was quantitated by RNase protection assay after 24 h (bottom panel). C: CD8⁺ T-cells were isolated from the spleen of LCMV-immune BALB/c mice and cultured with LCMV-infected, irradiated, antigen-presenting cells in the presence or absence of 3 ng/ml rhTGF-β1. After 1 and 3 days in culture, T-cells were analyzed for apoptosis by flow cytometry after staining with annexin V. Data represents the average frequency of CD8⁺ T-cells stained with annexin V ± SD from three independent experiments. (Please see http://dx.doi.org/10.2337/db08-0609 for a high-quality digital representation of this figure.)