title: A superantigen-antibody fusion protein for T-cell immunotherapy of human B-lineage malignancies.
abstract: The bacterial superantigen staphylococcal enterotoxin A (SEA) is an efficient activator of cytotoxic T cells when presented on major histocompatibility complex (MHC) class II molecules of target cells. Our previous studies showed that such SEA-directed T cells efficiently lysed chronic B-lymphocytic leukemia (B-CLL) cells. Next, we made a mutated SEA-protein A (SEAm-PA) fusion protein with more than 1,000-fold reduced binding affinity for MHC class II compared with native SEA. The fusion protein was successfully used to direct T cells to B-CLL cells coated with different B lineage-directed monoclonal antibodies (MoAbs). In this communication, we constructed a recombinant anti-CD19-Fab-SEAm fusion protein. The MHC class II binding capacity of the SEA part was drastically reduced by a D227A point mutation, whereas the T-cell activation properties were retained. The Fab part of the fusion protein displayed a binding affinity for CD19+ cells in the nanomolar range. The anti-CD19-Fab-SEAm molecule mediated effective, specific, rapid, and perforin-like T-cell lysis of B-CLL cells at low effector to target cell ratios. Normal CD19+ B cells were sensitive to lysis, whereas CD34+ progenitor cells and monocytes/macrophages were resistant. A panel of CD19+ B-cell lines representing different B-cell developmental stages were efficiently lysed, and the sensitivity correlated with surface ICAM-1 expression. The anti-CD19-Fab-SEAm fusion protein mediated highly effective killing of tumor biopsy cells representing several types of B-cell non-Hodgkin's lymphoma (B-NHL). Humanized severe combined immune deficiency (SCID) mice carrying Daudi lymphoma cells were used as an in vivo therapy model for evaluation of the anti-CD19-Fab-SEAm fusion protein. Greater than 90% reduction in tumor weight was recorded in anti-CD19-Fab-SEAm-treated animals compared with control animals receiving an irrelevant Fab-SEAm fusion protein. The present results indicate that MoAb-targeted superantigens (SAgs) may represent a promising approach for T-cell-based therapy of CD19+ B-cell malignancies.
authors.affiliation: Department of Clinical Immunology, University Hospital, Uppsala, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Gidlöf
authors.forename: M
authors.initials: M
authors.lastname: Dohlsten
authors.forename: P
authors.initials: P
authors.lastname: Lando
authors.forename: T
authors.initials: T
authors.lastname: Kalland
authors.forename: C
authors.initials: C
authors.lastname: Sundström
authors.forename: T H
authors.initials: TH
authors.lastname: Tötterman
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000627:therapeutic use*; D018941:Antigens, CD19 / Q000276:immunology / Q000378:metabolism; D018952:Antigens, CD34 / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology; D002051:Burkitt Lymphoma; D002460:Cell Line; D003602:Cytotoxicity, Immunologic; D004768:Enterotoxins / Q000235:genetics; D005260:Female; D005822:Genetic Vectors / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000235:genetics / Q000627:therapeutic use; D016219:Immunotherapy, Adoptive; D007399:Interphase / Q000276:immunology; D008213:Lymphocyte Activation; D016393:Lymphoma, B-Cell / Q000276:immunology* / Q000628:therapy*; D008264:Macrophages / Q000276:immunology; D051379:Mice; D016513:Mice, SCID; D009000:Monocytes / Q000276:immunology; D016297:Mutagenesis, Site-Directed; D011993:Recombinant Fusion Proteins / Q000276:immunology* / Q000378:metabolism / Q000627:therapeutic use*; D012680:Sensitivity and Specificity; D013211:Staphylococcus aureus / Q000235:genetics / Q000276:immunology; D018089:Superantigens / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use*; D013601:T-Lymphocytes / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D018941:Antigens, CD19; D018952:Antigens, CD34; D004768:Enterotoxins; D000949:Histocompatibility Antigens Class II; D007140:Immunoglobulin Fab Fragments; D011993:Recombinant Fusion Proteins; D018089:Superantigens; C026066:enterotoxin A, Staphylococcal