title: Phenotypic detection of clonotypic B cells in multiple myeloma by specific immunoglobulin ligands reveals their rarity in multiple myeloma.
abstract: In multiple myeloma, circulating "clonotypic" B cells, that express the immunoglobulin rearrangement of the malignant plasma cell clone, can be indirectly detected by PCR. Their role as potential "feeder" cells for the malignant plasma cell pool remains controversial. Here we established for the first time an approach that allows direct tracking of such clonotypic cells by labeling with patient-specific immunoglobulin ligands in 15 patients with myeloma. Fifty percent of patients showed evidence of clonotypic B cells in blood or bone marrow by PCR. Epitope-mimicking peptides from random libraries were selected on each patient's individual immunoglobulin and used as ligands to trace cells expressing the idiotypic immunoglobulin on their surface. We established a flow cytometry and immunofluorescence protocol to track clonotypic B cells and validated it in two independent monoclonal B cell systems. Using this method, we found clonotypic B cells in only one out of 15 myeloma patients. In view of the assay's validated sensitivity level of 10(-3), this surprising data suggests that the abundance of such cells has been vastly overestimated in the past and that they apparently represent a very rare population in myeloma. Our novel tracing approach may open perspectives to isolate and analyze clonotypic B cells and determine their role in myeloma pathobiology.
authors.affiliation: Department of Oncology and Hematology, BMT with section Pneumology, University Medical Center Hamburg-Eppendorf, Hubertus Wald Tumorzentrum/University Cancer Center Hamburg, Hamburg, Germany. m.trepel@uke.de
authors.forename: Martin
authors.initials: M
authors.lastname: Trepel
authors.forename: Victoria
authors.initials: V
authors.lastname: Martens
authors.forename: Christian
authors.initials: C
authors.lastname: Doll
authors.forename: Janina
authors.initials: J
authors.lastname: Rahlff
authors.forename: Barbara
authors.initials: B
authors.lastname: Gösch
authors.forename: Sonja
authors.initials: S
authors.lastname: Loges
authors.forename: Mascha
authors.initials: M
authors.lastname: Binder
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology*; D015331:Cohort Studies; D000939:Epitopes / Q000737:chemistry; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D007136:Immunoglobulins / Q000737:chemistry*; D008024:Ligands; D009101:Multiple Myeloma / Q000097:blood / Q000276:immunology* / Q000473:pathology; D019151:Peptide Library; D010455:Peptides / Q000737:chemistry; D010641:Phenotype; D016133:Polymerase Chain Reaction / Q000379:methods; D011994:Recombinant Proteins / Q000737:chemistry; D012074:Remission Induction; D015203:Reproducibility of Results; D033581:Stem Cell Transplantation
chemical_list: D000939:Epitopes; D007136:Immunoglobulins; D008024:Ligands; D019151:Peptide Library; D010455:Peptides; D011994:Recombinant Proteins; D005982:Glutathione Transferase