Expression of PD-L1 and PD-1 on AML blasts and T cells prior to and during PEM therapy. PB- and BM-derived AML blasts (A-B) and T cells (C-F) were stained with fluorochrome-conjugated antibodies and analyzed by flow cytometry prior to and at various time points during PEM treatment. Blasts were defined as CD45^low cells and stained for PD-L1 expression. Furthermore, T cells were characterized as CD45⁺, CD3⁺, and CD4⁺ or CD8⁺ populations. CD8⁺ T cells (C-D) and CD4⁺ T cells (E-F) were analyzed for their expression of PD-1 and PD-L1. Values in the graphs represent the percentage of cells staining positive for each molecule at indicated different time points.