CD4 and classic Hodgkin lymphoma: In line with these findings, circulating CD4+ cytotoxic T cells (CD4+/GrB+/PD-1+ Th-1 effector memory cells) are more abundant in patients with relapsed refractory cHL and expression of MHC class II, but not MHC class I, on HRSC was associated with the response to nivolumab in the CheckMate 205 trial.