Use of a cocktail of monoclonal antibodies and human complement in selective killing of acute lymphocytic leukemia cells.
Autologous remission bone marrow is a potential source of repopulative stem cells after ablative chemoradiotherapy of tumor patients. Even with remission bone marrow, one major obstacle to use of autologous bone-marrow support is the danger of reinfusing viable tumor cells. This report describes a purging protocol with human complement, which seems suitable for eliminating acute lymphatic leukemia (ALL) cells of the common ALL type. Lysis of ALL blasts is induced with a cocktail of 3 monoclonal antibodies of IgM type (termed VIB-pool). These are directed against the CALLA (CD 10) antigen (VIL-AI antibody) and against 2 different epitopes of the CD24 surface structure (VIB-C5 and VIB-E3 antibodies). The purging efficiency was evaluated with leukemic cell lines of the common ALL type (Reh-6 and Nalm-6) and with blast cells from common ALL patients. Optimal lysis was obtained with antibody and human serum concentrations as low as 1 microgram/ml and 7% respectively. As a standard purging protocol we propose one 20-min incubation at room temperature with antibody followed by two 30-min incubations at 37 degrees C with 25% human complement. In dye exclusion test 99% purging efficiency and in clonogenic assays detecting elimination of up to 5 logs of clonogenic tumor cells 99.99% (= 4 logs) purging efficiency were achieved. Treatment with VIB-pool and human complement had no negative effect on the growth of the normal hemopoietic progenitor cells CFU-GM, CFU-E and BFU-E.
Sugita
K
K
Majdic
O
O
Stockinger
H
H
Holter
W
W
Köller
U
U
Peschel
C
C
Knapp
W
W
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001853:Bone Marrow / Q000473:pathology; D002460:Cell Line; D003165:Complement System Proteins / Q000276:immunology*; D003602:Cytotoxicity, Immunologic; D006412:Hematopoietic Stem Cells; D006801:Humans; D007945:Leukemia, Lymphoid / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D011817:Rabbits; D014410:Tumor Stem Cell Assay
D000911:Antibodies, Monoclonal; D003165:Complement System Proteins