Proleukin in Combination With Rituxan in Patients With Intermediate and High-Grade Non-Hodgkin's Lymphoma.

Inclusion: * Diagnosis: CD20+ B-cell non-Hodgkin's lymphoma (NHL) classified as intermediate- or high-grade according to the Working Formulation, subtypes D to H. Must have measureable progressive or refractory disease after no more than three prior chemotherapy regimens. Exclusion: * Clinically significant cardiac dysfunction, or a history of myocardial infarction or heart failure within 6 months of first study treatment * Clinically significant pulmonary dysfunction. * Liver disease (note hepatitis C seropositive subjects may be enrolled if they have no active disease as demonstrated by undetectable HCV viral loads, biopsy showing no active disease, and/or history of normal transaminases on at least three different dates within one year of first study treatment). * Symptomatic thyroid disease requiring medical intervention other than replacement treatment for hypothyroidism. * History of autoimmune disease. * History of positive serology for human immunodeficiency virus (HIV).