T cells were cultivated with DCs, irradiated B78-D14 or B16-EpCAM cells and trAb Surek or BiLu, respectively, as outlined in Materials and Methods. At different time points, surface expression of CD69 and CTLA-4 on CD4+ and CD8+ T cells was determined by FACS analyses. Mean values and standard deviations from 3 independent experiments are shown.