Figure 1:

Human CD8⁺ T cell differentiation and associated phenotypic markers. Tumor-specific phenotypes are shown in red. Upon antigenic encounter, naïve CD8⁺ T cells differentiate into effector cells and further differentiate into different states depending on antigen clearance and chronic/recurrent antigen loads. Memory T cells specific for yellow fever virus (YFV) and the common human pathogens Influenza virus (Flu), Epstein-Barr virus (EBV) and cytomegalovirus (CMV), as well as tumor-specific cells (stem-like/progenitor exhausted and terminally differentiated) are shown along a schematic continuum of antigen load/recurrence. Of note, CMV- and EBV-specific memory CD8⁺ T cells can adopt various phenotypes and even resemble the phenotype of tumor-specific stem-like CD8⁺ T cells. Figure created with BioRender.