Since NK cells play a major in the control of the metastatic spread (41), we hypothesized that the detection of high levels of sIL-15/IL-15Rα in the plasma of both lympho-depleted and non-lympho-depleted metastatic melanoma patients (24) could contribute to the exhaustion of NK cells in these patients. The gene discussed is IL15RA; the disease is metastatic melanoma.