OBJECTIVES: I. Determine the toxic effects of humanized anti-HER2 monoclonal antibodies when administered in combination with interleukin-2 (IL-2) in patients with solid tumors. II. Measure in vitro cytotoxicity using peripheral blood mononuclear cells, plasma, and target cell lines that express HER2 in this patient population. III. Phenotypically characterize effector cells at the time of antibody administration and 24 hours after three days of intermediate dose IL-2 pulsing in these patients. IV. Measure antitumor response in these patients.