RATIONALE: Interleukin-2 may stimulate a person's white blood cells to kill tumor cells. Histamine dihydrochloride may help interleukin-2 kill more tumor cells by making tumor cells more sensitive to the drug. It is not yet known if interleukin-2 is more effective with or without histamine dihydrochloride in treating stage IV melanoma that is metastatic to the liver.