Effect of continuously intravenously infused blinatumomab on the activation of peripheral CD8⁺ and CD4⁺ T cells during the first treatment cycle of MRD⁺ ALL patients. The expression of the immediate early activation marker CD69 on the surface of gated (A) CD8⁺ and (B) CD4⁺ T-cell subpopulations was determined by FACS at baseline and throughout treatment, and the percentages of activated, CD69⁺ T-cell subpopulations were calculated. Values of (A) 14 and (B) 15 assessable patients are shown at baseline and at the time point of maximal T-cell activation which occurred within the first 2 days after infusion start for all patients. Bars in the respective left subpanels give median percentages; brackets indicate P values. Individual patient correlations are shown in the respective right subpanels.