Indeed, CD4 enhancement of CD8 T cell infiltration was previously described for extracranial tumours in elegant studies by Sherman and colleagues, in which they showed that tumour antigen-specific CD4 T cells rendered the tumour microenvironment permissive for CD8 T cell entry and function through IFN-γ-dependent chemokine induction [31], [32]. Here, IFNG is linked to neoplasm.