DISEASE CHARACTERISTICS: Histologically confirmed prostate carcinoma For Phase I: progressive, androgen-independent disease required, i.e.: Elevated PSA despite castrate testosterone levels (below 50 ng/dl) documented on 3 successive occasions For Phase II: progressive disease after surgery or radiotherapy without prior hormonal therapy also eligible HLA-A1- or HLA-A2-positive disease required Measurable or evaluable disease required No active CNS metastases

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 70-100% Life expectancy: At least 12 weeks Hematopoietic: WBC greater than 3,000 Absolute lymphocytes greater than 1,000 Platelets greater than 100,000 Hb at least 9 g/dl Hepatic: Bilirubin less than 2.0 mg/dl OR SGOT less than 2 x ULN Renal: Creatinine no greater than 2.0 mg/dl OR Creatinine clearance at least 40 ml/min Cardiovascular: No NYHA class III/IV status Pulmonary: No severe debilitating pulmonary disease Other: No active infection requiring antibiotics Not HIV positive No history of hypersensitivity to interferon gamma or other vaccine component No serious intercurrent medical illness

PRIOR CONCURRENT THERAPY: Recovered from toxicity of any prior therapy Biologic therapy: No prior autologous or allogeneic tumor vaccines No concurrent other immunotherapy Chemotherapy: At least 4 weeks since chemotherapy No concurrent chemotherapy Endocrine therapy: Flutamide discontinued and subsequent progression prior to entry 3 consecutive rising PSA values at least 2 weeks apart No concurrent corticosteroids (except for life-threatening conditions) Medical hormonal therapy to maintain castrate testosterone levels required in the absence of orchiectomy Radiotherapy: At least 4 weeks since radiotherapy No concurrent radiotherapy Surgery: Prior surgery allowed