Intriguingly, the majority of T cells that infiltrate HL tumors are IFNγ-expressing TH1-polarized CD4+ T cells (96, 97), which is again at odds with the concept that PD-1 inhibition works solely through the reactivation of MHC class I-restricted CD8+ T cells (98), given that cHL is sensitive to this immunotherapy. Here, CD4 is linked to Hodgkins lymphoma.