mRNA-electroporated moDCs and LCs remain potent inducers of allogeneic T cell proliferation, including after cryopreservation and thawing. (A) MoDCs and LCs, as indicated on the x axes, were electroporated with WT1 mRNA (○), eGFP mRNA (△), or mock-electroporated with no mRNA (□). After electroporation, DCs were terminally matured for 24 hours and then cultured with allogeneic T cells for five days in allogeneic MLRs. DC:T ratios ranged from 1:10 to 1:1000. [3H]TdR uptake by proliferating allogeneic T cells over the final 8 hours of culture was measured as an index of DC immunogenicity (triplicate means ± SEM, n = 3 independent experiments). (B) To assess preservation of allo-stimulatory capacity in MLRs after cryopreservation and thawing, WT1 mRNA-electroporated moDCs (△) and LCs (○) were compared with non-cryopreserved mature moDCs (▤). Culture conditions were otherwise exactly the same as in (A). T cell proliferation was measured by a colorimetric assay (triplicate means ± SEM, n = 3 independent experiments). Dotted line represents T cells alone.