Immunophenotypic analysis of lymphocytes and myeloma cells in patients with multiple myeloma.

The immunological phenotypes of lymphocytes and myeloma cells in 48 patients with multiple myeloma (MM) were analyzed using a panel of monoclonal antibodies (mAbs). Myeloma cells were positive for OKT10, BL3, PCA1 and BA2. In a few cases, they were also positive for the B cell-associated antigens J5, B1 and I2. Eight of 48 cases had more than 15% J5-positive lymphocytes, and some lymphocytes in MM expressed plasma cell-associated antigens (PCA1, BL3, OKT10), suggesting a possible clonal involvement. These observations demonstrate the heterogeneity of surface antigen expression of myeloma cells and suggest that BL3, PCA1, BA2 and J5 may be useful mAbs for purging myeloma cells from bone marrow for autologous transplantation.