bilirubin. (Gilbert syndrome is found in 3-10% of the general population, and is characterized by mild, chronic unconjugated hyperbilirubinemia in the absence of liver disease or overt hemolysis). On cohort B, patients with liver involvement by tumor will not be eligible due to potential confounding risk for hepatotoxicity when rhIL15 is administered. NOTE: adult values will be used for calculating hepatic toxicity on this trial, as is standard on POB phase I trials.