IL2 and neoplasm: Reports of tumor-resident and systemic immune responses in melanoma patients, clinical observations of partial lesion regressions and spontaneous remissions, increased rates of malignant melanoma in immunosuppressed patients (organ transplant recipients and HIV-infected individuals),9,10 as well as partial successes of early immunostimulating treatments such as interleukin-2 (IL-2) and interferon-α2b (IFNα-2b) reported over many years, together support the presence of an active immune surveillance in patients with melanoma.11