Figure 2.

Expression of CD25 and il-12rβ2 and in vitro proliferation in MLC of naïve CD4⁺CD25⁺ T cells. (A) Comparison of naïve CD4⁺CD25⁺ T cells before and after culture with rIL-2 and alloantigen. The majority of CD4⁺ T cells expressed CD25 before culture (nTreg) and remained CD25⁺ post-culture with rIL-2 and alloantigen (Ts1). Replicated in several experiments. (B) Expression of il-12rβ2 in CD4⁺CD25⁺ T cells (nTreg) from DA rats cultured for 3 days with DA (auto) or PVG (allo) stimulators in the presence of rIL-2, rIL-4, or no cytokines. The CD25⁺ population was re-enriched to remove stimulator cells. il-12rβ2 was increased in CD4⁺CD25⁺ T cells cultured with rIL-2 and alloantigen to induce Ts1 cells and to a lesser extent with autoantigen. There was no il-12rβ2 expression in nTreg cultured with alloantigen alone with no cytokine as well as those cultured with rIL-4 and auto- or alloantigen. There was no expression of il-2, confirming no Th1 induction after culture with rIL-2, ifngr was induced, but not with rIL-4, as described (8) (data not shown). One of three experiments with similar results. (C) Proliferation of Ts1 cells re-cultured with alloantigen and rIL-12p70. nTreg were simulated with PVG stimulators and rIL-2 for 4 days to produce Ts1 cells that were washed and then re-stimulated for 3 days with PVG stimulators alone or with rIL-12p70, rIL-12p40, rIL-2, or control (supernatant from non-transfected CHO-K). Only rIL-2 (p < 0.05) and rIL-12p70 (p < 0.05) induced significant proliferation compared to controls, with no cytokine or with supernatant from non-transfected CHO-K cells. This induction of proliferation by rIL-12p70 demonstrated a functional significance of il-12rβ2 expression by Ts1 cells.