Antibody-targeted superantigens induce lysis of major histocompatibility complex class II-negative T-cell leukemia lines.
CTLs bearing certain T-cell receptor V beta-regions are directed by the bacterial superantigen Staphylococcus enterotoxin A (SEA) to lyse MHC class II-positive cells. In order to extend superantigen-dependent cytotoxicity to MHC class II-negative carcinoma cells, covalent conjugates of superantigen and mAbs against surface markers of these cells have been used. We now describe a novel strategy which allows rapid selection of mAb suitable for superantigen targeting against MHC class II-negative tumor cells. A recombinant fusion protein of protein A and SEA binding to the mAbs CD7 or CD38 was able to mediate T cell-dependent lysis of MHC class II-negative Molt-4 and CCRF-CEM acute lymphatic leukemia cell lines. Lysis was dose dependent and correlated with E:T cell ratio. In contrast, SEA alone did not induce any significant lysis. In order to decrease the MHC class II affinity of the protein A-SEA complex, a point mutation was introduced into SEA (protein A-SEA mu9). The mutated fusion protein had similar potency as protein A-SEA against Molt-4 cells but was 100-fold less active against MHC class II-positive cells. Considering the efficiency and specificity of the mutated SEA protein interacting with mAb in targeting T lymphocytes against MHC class II-negative leukemia cells while only marginally affecting normal MHC class II-positive cells, we suggest the development of SEA-mAb fusion proteins as a potential adjuvant therapy of leukemias.
Ihle
J
J
Department of Oncology/Hematology, Children's University Hospital, Tübingen, Germany.
Holzer
U
U
Krull
F
F
Dohlsten
M
M
Kalland
T
T
Niethammer
D
D
Dannecker
G E
GE
D036541:ADP-ribosyl Cyclase; D051997:ADP-ribosyl Cyclase 1; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000032:analysis / Q000096:biosynthesis / Q000276:immunology; D019011:Antigens, CD7; D000943:Antigens, Differentiation / Q000276:immunology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology; D002460:Cell Line; D003001:Cloning, Molecular; D003602:Cytotoxicity, Immunologic; D004768:Enterotoxins / Q000633:toxicity*; D006681:HLA-D Antigens / Q000276:immunology*; D006801:Humans; D000922:Immunotoxins / Q000633:toxicity*; D015458:Leukemia, T-Cell / Q000276:immunology*; D008562:Membrane Glycoproteins; D011993:Recombinant Fusion Proteins / Q000633:toxicity; D013211:Staphylococcus aureus; D018089:Superantigens / Q000633:toxicity*; D013601:T-Lymphocytes / Q000276:immunology*; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D019011:Antigens, CD7; D000943:Antigens, Differentiation; D000945:Antigens, Differentiation, T-Lymphocyte; D004768:Enterotoxins; D006681:HLA-D Antigens; D000922:Immunotoxins; D008562:Membrane Glycoproteins; D011993:Recombinant Fusion Proteins; D018089:Superantigens; C026066:enterotoxin A, Staphylococcal; D036541:ADP-ribosyl Cyclase; C498154:CD38 protein, human; D051997:ADP-ribosyl Cyclase 1