title: Removal of cells from a malignant B-cell line from bone marrow with immunomagnetic beads and with complement and immunoglobulin switch variant mediated cytolysis.
abstract: In this report we describe the generation of complement (C') fixing IgG2b CD19 and CD22 monoclonal antibodies (mAbs) by the isolation of immunoglobulin (Ig) class switch variants using a simple and efficient method for the selection of spontaneously mutating hybridomas. The aim of this study was to compare the efficacy of C'-mediated cytolysis vs immunomagnetic (IB) depletion of tumor cells from mixtures of malignant B cells and normal bone marrow. In a clonogenic assay employing the B-cell lines Namalwa and OCI.LY1, we found that the use of immunomagnetic beads warranted a highly efficient tumor cell removal independent of the Ig isotype of the mAbs used. Elimination of up to 4 log was achieved using a cocktail consisting of CD19, CD20, CD22 and CD37 B-cell mAbs. A less efficient killing of 2 log was obtained by C' lysis using IgM mAbs, while only about 1 log tumor cell elimination was obtained using IgG2b mAbs. Immunomagnetic purging, besides being more effective than C'-mediated cytolysis, is easier to handle and more rapid.
authors.affiliation: Department of Internal Medicine, University of Heidelberg, Federal Republic of Germany.
authors.forename: S
authors.initials: S
authors.lastname: Kiesel
authors.forename: R
authors.initials: R
authors.lastname: Haas
authors.forename: G
authors.initials: G
authors.lastname: Moldenhauer
authors.forename: G
authors.initials: G
authors.lastname: Kvalheim
authors.forename: A
authors.initials: A
authors.lastname: Pezzutto
authors.forename: B
authors.initials: B
authors.lastname: Dörken
mesh_terms: D000911:Antibodies, Monoclonal; D001402:B-Lymphocytes / Q000276:immunology / Q000473:pathology*; D001854:Bone Marrow Cells; D002460:Cell Line; D002469:Cell Separation / Q000379:methods*; D003114:Colony-Forming Units Assay; D003165:Complement System Proteins; D003602:Cytotoxicity, Immunologic; D006412:Hematopoietic Stem Cells / Q000032:analysis; D006801:Humans; D007134:Immunoglobulin Switch Region; D007158:Immunologic Techniques; D008228:Lymphoma, Non-Hodgkin / Q000473:pathology; D008280:Magnetics
chemical_list: D000911:Antibodies, Monoclonal; D003165:Complement System Proteins