title: G19.4(alpha CD3) x B43(alpha CD19) monoclonal antibody heteroconjugate triggers CD19 antigen-specific lysis of t(4;11) acute lymphoblastic leukemia cells by activated CD3 antigen-positive cytotoxic T cells.
abstract: A highly purified, 300-Kd bispecific monoclonal antibody (MoAb) heteroconjugate was prepared by covalently linking the anti-CD3 MoAb, G19.4, to the anti-CD19 MoAb, B43. Dual-color staining techniques and multiparameter flow cytometry confirmed that this alpha CD3 x alpha CD19 heteroconjugate was able to bind to both CD3+ T cells and CD19+ t(4;11) acute lymphoblastic leukemia (ALL) cells. T-cell-mediated lysis of freshly isolated primary bone marrow blasts from nine newly diagnosed ALL patients with a t(4;11)(q21;q23) chromosomal translocation were studied with 51Cr-release assays. Picomolar concentrations of alpha CD3 x alpha CD19 MoAb heteroconjugate effectively triggered lysis of CD19+ t(4;11) ALL cells by interleukin-2-activated CD3+ peripheral blood T-cell (PBTC) effectors but did not augment the cytolytic activity of the same effectors against CD19- T-ALL cells. In contrast to the alpha CD3 x alpha CD19 heteroconjugate, neither the alpha CD3 x alpha CD3 homoconjugate control nor the alpha CD19 x alpha CD72 heteroconjugate control facilitated the cytolysis of t(4;11) ALL blasts. Occupation of the target CD19 binding sites on t(4;11) ALL blasts by preincubation with excess unconjugated alpha CD19 MoAb abrogated the potentiating effects of the alpha CD3 x alpha CD19 heteroconjugate on PBTC-mediated cytolysis. Thus, the cell type-specific cytolysis of t(4;11) ALL blasts by PBTC effectors is dependent on both the alpha CD19 and alpha CD3 moieties of the alpha CD3 x alpha CD19 heteroconjugate. To our knowledge, this is the first description of an effective bispecific antibody that facilitates the T-cell-mediated lysis of t(4;11) ALL blasts.
mesh_terms: D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000276:immunology*; D018941:Antigens, CD19; D000944:Antigens, Differentiation, B-Lymphocyte / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D001853:Bone Marrow / Q000276:immunology / Q000473:pathology; D017252:CD3 Complex / Q000276:immunology*; D002648:Child; D002880:Chromosomes, Human, Pair 11; D002894:Chromosomes, Human, Pair 4; D003602:Cytotoxicity, Immunologic; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D008213:Lymphocyte Activation; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics* / Q000276:immunology*; D014178:Translocation, Genetic
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D018941:Antigens, CD19; D000944:Antigens, Differentiation, B-Lymphocyte; D017252:CD3 Complex; D007376:Interleukin-2