PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Not specified Life expectancy: Not specified Hematopoietic: Not specified Hepatic: Albumin at least 3.0 mg/dL Renal: Not specified Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception for at least 28 days prior to and during study No known hypersensitivity to denileukin diftitox or its components (e.g., diphtheria toxin, interleukin-2, or its excipients) or to dexamethasone No concurrent serious, uncontrolled infection that would preclude study