Multiple myeloma related cells in patients undergoing autologous peripheral blood stem cell transplantation

A high incidence of oligoclonal serum M-components is observed in multiple myeloma (MM) patients treated with autologous Stem cell transplantation (AS CT). To determine whether these hi-components are produced by myeloma clona lly related cells or caused by an aberrant B-cell regeneration we analysed by semi-nested ASO-RT-PCR and DNA sequencing the immunoglobulin (Ig) variab le genes (VH) obtained from bone marrow samples obtained before and after t ransplantation and peripheral blood stern cell (PBSC) samples from seven pa tients. Myeloma clonally related cells are identifiable by the expression of varian t Ig heavy chain isotypes and were detected in two patients at presentation . No myeloma clonally related cells were found in post-transplantation samp les (n = 7) in spite of the appearance of new serum M-components, However, in two cases we amplified sequences from post-transplantation bone marrow c ells that were able to bind to the B-cell clone-specific CDR3 oligonucleoti des but showed no further similarity regarding the VDT rearrangement, These data indicate that serum oligoclonality posttransplantation is not ca used by myeloma clonally related B cells but rather by the regenerating B-c ell compartment.