Inclusion Criteria

DISEASE CHARACTERISTICS:

- Diagnosis of multiple myeloma meeting 1 of the following criteria:

- Bone marrow plasmacytosis with at least 10% plasma cells

- Sheets of plasma cells

- Biopsy-proven plasmacytoma

- Meets at least 1 of the following criteria:

- Presence of myeloma (M)-protein in the serum

- Presence of M-protein in the urine

- Radiographic evidence of osteolytic lesions

- Generalized osteoporosis allowed if at least 20% plasma cells in bone
marrow

- No non-secretory myeloma

- Prior M-protein in serum or urine allowed provided patient is now in complete
remission

- Must be receiving conventional-dose chemotherapy as initial therapy or as salvage
therapy

- Must have HLA-A, -B, and -DR genotypically identical sibling donor

PATIENT CHARACTERISTICS:

Age:

- 18 to 70

Performance status:

- ECOG 0-2

Life expectancy:

- Not specified

Hematopoietic:

- See Disease Characteristics

Hepatic:

- AST no greater than 3 times upper limit of normal

- Bilirubin less than 2.0 mg/dL

Renal:

- Not specified

Cardiovascular:

- LVEF greater than 40% at rest if symptomatic cardiac disease is present

Pulmonary:

- DLCO greater than 50% of predicted (corrected for hemoglobin) if symptomatic
pulmonary disease is present

Other:

- Not pregnant or nursing

- Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

- No prior autologous or allogeneic peripheral blood stem cell or bone marrow
transplantation

Chemotherapy:

- See Disease Characteristics

- More than 28 days since prior chemotherapy (including primary chemotherapy for
hematopoietic stem cell collection)

- No other concurrent cytotoxic chemotherapy between autologous and allogeneic
transplantation

Endocrine therapy:

- Prior dexamethasone or other corticosteroids allowed

- Concurrent corticosteroids between autologous and allogeneic transplantation allowed

Radiotherapy:

- Concurrent radiotherapy between autologous and allogeneic transplantation allowed

Surgery:

- Not specified