title: Monoclonal antibodies with neuroblastoma specificity: a flow cytometric analysis of cross-reactivity with CD34+ hematopoietic stem cells.
abstract: The aim of this study was to evaluate the specificity of a number of monoclonal antibodies (MAbs) used for immunological in vitro purging of stem cell grafts from neuroblastoma patients. The extent of cross-reactivity of 10 neuroblastoma-specific MAbs (NB-MAb) with CD34+ stem cells from 14 leukapheresis products was analyzed. The level of cross-reactivity was analyzed on a Coulter (Fullerton, CA) flow cytometer using biotinylated NB-MAbs. There was a marked difference in the reactivity of the ten NB-MAbs with CD34+ stem cells. The antibodies could be divided into three groups with increasing levels of cross reactivity. Four antibodies (126-4, 5.1 H11, UJ127.11, and 14.G2a) all reacted with median levels of less than 2% (range 0.0 to 5.4) of CD34+ stem cells (median of 14 patients). Another three antibodies reacted with a median of 3.1-4.1% of the stem cells (UJ13A, Ab390, and Ab459) but with a wide range (0.2 to 25.6). Finally, M340, HSAN 1.2, and antiThy-1 reacted with a median of 9-16% of the stem cells (range 0.6 to 51.5). We conclude that there is a significant variation in the proportion of CD34+ stem cells reacting with each of the ten neuroblastoma antibodies investigated in this study. Therefore, to avoid a significant loss of CD34+ cells from the stem cell product, we find it important to carefully consider which antibodies to use for immunomagnetic purging.
authors.affiliation: Clinical Immunological Department, Bloodbank 2034, Laboratory Centre, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark. ifversen@rh.dk
authors.forename: M
authors.initials: M
authors.lastname: Ifversen
authors.forename: L D
authors.initials: LD
authors.lastname: Christensen
authors.forename: C
authors.initials: C
authors.lastname: Rechnitzer
authors.forename: C
authors.initials: C
authors.lastname: Heilmann
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D018952:Antigens, CD34 / Q000097:blood; D001781:Blood Component Removal / Q000592:standards; D003429:Cross Reactions / Q000276:immunology; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000276:immunology; D051379:Mice; D009447:Neuroblastoma / Q000276:immunology*; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D018952:Antigens, CD34