Bcl-2 overexpression in cardiac allografts does not modulate the allospecific host immune cell response in the spleen. Splenocytes from recipient mice were prepared at 1, 3, 5, and 7 days after heart transplantation (n = 3 each), as described in “Materials and methods.” (A) Expression levels of IFN-γ and TNF-α on splenic CD4⁺ or CD8⁺ T cells from host C57BL/6 mice that received transplanted Bcl-2 Tg hearts and WT hearts were assessed by intracellular cytokine staining analysis using flow cytometry. Splenocytes from recipient mice were prepared at 7 days (n = 5 each) after heart transplantation, as described in “Materials and methods.” (B) Anti-FVB (stimulator) activity of C57BL/6 splenocytes from WT naive (control) mice, mice that received transplanted WT hearts, and mice that received transplanted Bcl-2 Tg hearts was assessed by a mixed lymphocyte reaction. Filled columns show the data from WT heart grafts, and open columns show data from the Bcl-2 Tg heart grafts. Data are representative of 3 separate experiments. Mean ± SD values are shown. NS indicates not significant.