CD4 and classic Hodgkin lymphoma: CHL has the most heterogenous cellular composition among lymphomas, consisting of various innate (e.g., eosinophils, neutrophils, mast cells, macrophages, NK cells) and adaptive (B cells, plasma cells, CD4+ helper (Th) and regulatory (Treg) T cells, CD8+ T cells) immune cell types, stroma cells, and fibroblasts.