CD4 and neoplasm: Given that the sensitivity of detection of metastases from DLN in our limiting dilution assay is ∼1∶107 cells, and that anti-CD4 treatment of immunotherapy-treated EMT6 tumor injected mice reveals increased metastases in mice otherwise “cured” of disease, we speculate that such mice may harbor quiescent tumor cells, whose growth is held in check by mechanisms which are CD4-dependent.