CD4 and neoplasm: Interestingly, recent reports by Torcellan and co-workers demonstrated by in vivo photolabeling of subcutaneous tumors, that tumor-egressing T-cells constitute an heterogeneous population that includes relatively high numbers of CD4+ and CD8+ T lymphocytes with effector phenotypes and moderate amounts of IL-17 producing CD4-CD8- double negative T lymphocytes (13).