Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed metastatic adenocarcinoma of the prostate

- HLA-A2 positive

- Progressive measurable systemic disease

- PSA at least 5 ng/mL with 2 consecutive rising PSA levels at least 1 week apart
and no measurable disease OR

- Objective evidence of disease progression by a 20% increase in the sum of
longest diameter of all target lesions or evidence of new lesions by CT or bone
scan regardless of PSA status

- Lesions must be at least 1 cm to be considered measurable

- Progressive systemic disease after discontinuation of anti-androgen therapy

- Previously treated with orchiectomy (testosterone less than 50 ng/mL) OR luteinizing
hormone-releasing hormone (LHRH) analogue therapy with or without anti-androgens

- If on LHRH analogue therapy, must continue therapy during study

- Brain metastases allowed if previously treated, clinically stable, and weaned from
prior corticosteroids

PATIENT CHARACTERISTICS:

Age:

- Over 18

Performance status:

- Karnofsky 70-100%

Life expectancy:

- At least 12 weeks

Hematopoietic:

- Absolute neutrophil count greater than 1,500/mm^3

- Hemoglobin greater than 9 g/dL

- Platelet count greater than 100,000/mm^3

- No active gastrointestinal bleeding

Hepatic:

- Bilirubin less than 1.5 times upper limit of normal (ULN)

- SGPT normal

- Hepatitis B surface antigen negative

Renal:

- Creatinine less than 1.5 times ULN

- Calcium less than 11 mg/dL

Cardiovascular:

- No significant cardiovascular disease

- No cardiac arrhythmia requiring therapy

Other:

- Fertile patients must use effective barrier contraception

- No intrinsic immunosuppression

- HIV negative

- No serious concurrent infection

- No psychiatric illness that would preclude study compliance

- No clinically significant autoimmune disease

- No uncontrolled peptic ulcer disease

- No history of inflammatory bowel disease

PRIOR CONCURRENT THERAPY:

Biologic therapy:

- At least 4 weeks since prior biologic therapy

Chemotherapy:

- Not specified

Endocrine therapy:

- See Disease Characteristics

- At least 4 weeks since prior flutamide

- At least 6 weeks since prior bicalutamide or nilutamide

- No concurrent systemic corticosteroids except physiologic replacement doses

Radiotherapy:

- Not specified

Surgery:

- See Disease Characteristics

Other:

- No concurrent immunosuppressive drugs (e.g., cyclosporine)