DISEASE CHARACTERISTICS:

• Histologically confirmed recurrent or persistent multiple myeloma at least 6 months following allogeneic bone marrow transplantation (BMT) from an HLA identical sibling

• Must meet one of following criteria to be considered persistent, recurrent, or progressive disease:

  • Residual detectable disease 6-12 months after BMT, as determined by the M protein level or bone marrow involvement, without further evidence of clinical or laboratory improvement on 2 consecutive measurements 4 weeks apart
  • Complete response not achieved 12 or more months after BMT and there is no evidence of progressive improvement
  • At least 25% increase of serum paraprotein (greater than 1.0 g/dL) as measured on two occasions or a 50% increase in urinary light chain excretion (greater than 150 mg/day) as measured on 2 occasions
  • A 10% increase in plasma cells in the bone marrow
• Disease in complete response but with recurrence of M protein and 10% point increase in myeloma cells in the marrow allowed
• No lytic lesions alone or new soft tissue plasmacytoma as sole evidence of progression

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• ECOG 0-2

Life expectancy:

• More than 4 weeks

Hematopoietic:

• Not specified

Hepatic:

• Bilirubin no greater than 2.0 times upper limit of normal

Renal:

• Not specified

Other:

• No active infection
• Not pregnant or nursing
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Must have received prior allogeneic bone marrow transplantation from an HLA A;B;DR genotypically matched sibling donor
• No concurrent interferon therapy for relapsed disease

Chemotherapy:

• At least 4 weeks since cyclosporine, methotrexate, azathioprine, or other graft versus host disease (GVHD) prophylaxis/treatment without evidence of flare of GVHD
• At least 4 weeks since prior chemotherapy for relapsed disease

Endocrine therapy:

• Must be receiving a dose no greater than 0.25 mg/kg prednisone for at least 4 weeks prior to registration without flare of GVHD
• No prior prednisone dose greater than 0.25 mg/kg in the past 4 weeks
• Must receive concurrent prednisone of a dose no greater than 0.25 mg/kg
• Concurrent corticosteroids allowed

Radiotherapy:

• Concurrent palliative radiotherapy allowed if evidence of other evaluable disease other than irradiated bony sites

Surgery:

• Not specified