The immunogenicity of Bcr-Abl–expressing dendritic cells is dependent on the Bcr-Abl kinase activity. (A) CD8⁺ T-cell populations from a healthy donor (HD no. 1, Table S1) were primed with autologous Bcr-Abl WT⁺ DCs. IFN-γ production was tested 1 week after the third stimulation in an ELISpot assay. Every single T-cell population was divided into 3 aliquots and coincubated with autologous Bcr-Abl WT⁺ DCs, Bcr-Abl KD⁺ DCs, or mock-transfected DCs to provoke IFN-γ release by the T cells. The scatterplots show the number of IFN-γ spots produced by every T-cell population (n = 60) after incubation with the respective DCs (left and middle). Incubation with Bcr-Abl WT⁺ DCs resulted in higher IFN-γ production compared with Bcr-Abl KD⁺ DCs or mock-transfected DCs. The magnitudes of responses against Bcr-Abl WT⁺ (▒) or KD⁺ DCs (░) were compared in a box plot showing the median distribution of IFN-γ–producing T-cell populations (right). Black lines in boxes indicate median spot value; boxes represent interquartile range; whiskers extend from the 10th percentile at the bottom and the 90th percentile at the top. (B) CD8⁺ T-cell populations from the same donor were primed with autologous Bcr-Abl KD⁺ DCs. IFN-γ production of T cells was assessed 1 week after the third stimulation in an ELISpot assay (left and middle). Incubation with Bcr-Abl WT⁺ or Bcr-Abl KD⁺ DCs as stimulator cells did not result in an increased IFN-γ production compared with the mock control. Statistical evaluation of the magnitudes of responses against Bcr-Abl WT⁺ DCs (▒) or Bcr-Abl KD⁺ DCs (░) (right). (A-B) Similar results have been obtained from additional 2 healthy donors (HD no. 2 and HD no. 4). (C) GrzB release by CD8⁺ T cells after 3 stimulations with Bcr-Abl WT⁺ DCs (left) or Bcr-Abl KD⁺ DCs (right) derived from HD no. 3 in the presence of autologous Bcr-Abl WT⁺ DCs (▒) and Bcr-Abl KD⁺ DCs (░) (*P < .001; **P = ns; Mann-Whitney test). (D) IFN-γ release of CD8⁺ T-cell populations (n = 60) that had been generated by repetitive stimulation with Bcr-Abl WT⁺ DCs derived from HD no. 5, either untreated (left) or IM treated (right). To provoke IFN-γ release, the autologous Bcr-Abl WT⁺ DCs were pretreated with IM or left untreated prior to coculture with the established T-cell populations. The box plot shows the median distribution of IFN-γ–producing T-cell populations after incubation with untreated (▒) or IM pretreated (░) Bcr-Abl WT⁺ DCs (*P < .001; **P = ns; Mann-Whitney test).