Figure 2.

Expanded DCs are capable of inducing alloreactive proliferation and TNF-α production after PHA stimulation. We analyzed the capacity of eDCs to induce proliferation in a MLR. Splenocytes (2 × 10⁵) from C57BL/6 mice were co-cultured with irradiated eDCs at variable numbers at the indicated ratios of responder (R) to stimulator (S) cells. A: In the syngeneic setting C57BL/6 splenocytes showed minimal proliferation when exposed to irradiated eDCs of the same origin. B: In contrast, responder cells (C57BL/6 splenocytes) proliferated vigorously against irradiated eDCs of allogeneic origin (BALB/c) in a dose-dependent manner. C: Syngeneic transduced eDCs induced only minimal proliferation and were therefore similar to syngeneic WT eDCs. D: In contrast allogeneic transduced eDCs induced a vigorous proliferation that was similar to the one induced by allogeneic WT eDCs. The controls demonstrated only a low level of proliferation of unstimulated splenocytes (C57BL/6 origin), in contrast to a high level of proliferation (∼30,000 cpm) in the allogeneic control (C57BL/6:irradiated BALB/c splenocytes, at a ratio of 1:1). E: Cytokine production of eDCs from C57BL/6 WT mice, transduced gfp⁺luc⁺ eDCs, and eDCs from gfp⁺ transgenic mice (OSB) was assessed for TNF-α production by cytometric bead array immunoassays. After stimulation with PHA the three groups displayed a comparable high level of TNF-α production of more than 5000 pg/ml. The unstimulated control samples of each group were also comparable, in showing only a low basal level of TNF-α secretion.