DISEASE CHARACTERISTICS: Histologically proven adenocarcinoma of the prostate Previously treated with radical prostatectomy at least 3 months ago HLA-A2 positive PSA greater than 0.5 ng/mL and rising At least 0.3 ng/mL greater than post-prostatectomy nadir Confirmed by at least 2 additional PSA levels at least 2 weeks apart No bone metastases by bone scan within past 3 months No clinical evidence of local disease recurrence (no palpable mass or induration in prostatic fossa)