Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed metastatic breast cancer that expresses carcinoembryonic
antigen (CEA)

- At least 25% of the tumor cells must stain positive for CEA with at least
moderate intensity

- Must have achieved either partial response or complete response after high dose
chemotherapy and peripheral blood stem cell transplant

- Hormone receptor status:

- Not specified

PATIENT CHARACTERISTICS:

Age:

- 18 and over

Menopausal status:

- Not specified

Performance status:

- Karnofsky 70-100%

Life expectancy:

- Greater than 6 months

Hematopoietic:

- Absolute neutrophil count at least 1000/mm^3

- Absolute lymphocyte count at least 1000/mm^3

- Hemoglobin at least 9 mg/dL

- Platelet count at least 100,000/mm^3

Hepatic:

- Bilirubin less than 2.0 mg/dL

- No serious ongoing chronic or acute hepatic disease

Renal:

- Creatinine less than 2.5 mg/dL

Cardiovascular:

- No serious ongoing chronic or acute cardiac disease (New York Heart Association class
III or IV)

Pulmonary:

- No serious ongoing chronic or acute pulmonary illness such as asthma, chronic
obstructive pulmonary disease, or radiation or drug induced pneumonitis

Other:

- No other prior or concurrent malignancy except nonmelanoma skin cancer or controlled
superficial bladder cancer within the past 5 years

- No history of autoimmune disease such as inflammatory bowel disease, systemic lupus
erythematosus, rheumatoid arthritis, ankylosing spondylitis, scleroderma, or multiple
sclerosis

- No inflammatory bowel condition such as active infectious enteritis or eosinophilic
enteritis

- No active acute or chronic infection such as urinary tract infection, HIV, or viral
hepatitis

- Not pregnant or nursing

PRIOR CONCURRENT THERAPY:

Biologic therapy:

- See Disease Characteristics

- No concurrent immunotherapy

Chemotherapy:

- See Disease Characteristics

- No concurrent chemotherapy

Endocrine therapy:

- At least 4 weeks since steroids

- No concurrent steroid therapy

Radiotherapy:

- No concurrent radiotherapy

Surgery:

- Not specified

Other:

- No concurrent immunosuppressive agents such as azathioprine or cyclosporine A