CD4 and neoplasm: These cells can mediate both pro-and anti-tumor effects and perform a plethora of roles in the tumor milieu, such as secretion of antibodies and cytokines, antigen presentation for both cytotoxic (CD8+) and helper (CD4+) T lymphocytes, and coordination and maintenance of lymphoid aggregates known as tertiary lymphoid structures (TLS), which are privileged sites for antigen presentation and T cell (re-)activation (Sautes-Fridman et al., 2019; Sharonov et al., 2020).