Isolation and characterization of human multiple myeloma cell enriched populations

We developed a simple and rapid method to enrich tumor cells within bone ma rrow (BM) aspirates from patients with multiple myeloma (MM). Thirty patien ts with a median of 50% (8-85%) MM cells by morphology and 55% (6-85%) MM c ells identified by CD38 + CD45 - cell surface phenotype were studied. BM mo nonuclear cells (BMMCs) were isolated by Ficoll Hypaque sedimentation and i ncubated with a cocktail of mouse monoclonal antibodies (mAbs) directed aga inst CD3 (T cells); CD11b and CD14 (monocytes); CD33 (myeloid cells), CD45 and CD45RA (leucocyte common antigen); CD32 as well as glycophorin A, After the addition of anti-mouse Fc Ig-coated immunomagnetic beads, mAb-bound ce lls were removed in a magnetic field. The residual cell populations were en riched for MM cells, evidenced by > 95% plasma cell morphology and > 95% CD 38 + CD45RA - cell surface phenotype. Since this method requires only two s hort incubations, cell losses were minimal and the yield of MM cells was th erefore high (> 95%). Viability of the MM-cell enriched fractions was 99%, and these cells were functional in assays of proliferation, cell cycle anal ysis and immunoglobulin secretion. This immunomagnetic bead depletion metho d therefore permits the ready isolation of homogeneous populations of patie nt MM cells for use in both cellular and molecular studies. (C) 2000 Elsevi er Science B.V. All rights reserved.