Isolation of bone marrow plasma cells by negative selection with immunomagnetic beads.

In order to isolate bone marrow plasma cells from patients presenting with multiple myeloma or monoclonal gammopathy of undetermined significance, we developed a method for purifying these cells by negative selection using monoclonal antibodies and immunomagnetic beads. The results presented here were obtained from 75 procedures. Purity was extremely variable (2-100%) and was dependent on the percentage of plasma cells in the original bone marrow sample with a 10% cut-off, beyond which purity was over 96% in all cases. The mean yield was about 20%. The cells collected were viable and suitable for immunophenotyping, semi-quantitative studies of oncoproteins, and PCR.