PRIOR CONCURRENT THERAPY: Biologic therapy: No other concurrent immunotherapy Chemotherapy: At least 3 weeks since prior chemotherapy (6 weeks for mitomycin or nitrosoureas) and recovered No concurrent chemotherapy Endocrine therapy: No chronic steroid therapy Radiotherapy: At least 3 months since prior localized radiotherapy (e.g., pelvic or small field) and recovered No radiotherapy to whole abdomen No concurrent radiotherapy Surgery: Recovered from prior surgery At least 3 weeks since prior major abdominal surgery At least 2 weeks since prior laparoscopy