title: Ricin A immunotoxins of IgG and Fab of anti-CALLA monoclonal antibody: effect of water soluble long-chain SPDP on conjugate yield, immunoselectivity and cytotoxicity.
abstract: The water soluble long-chain crosslinker, sulfo-succinimidyl-6-[3'-(2-pyridyldithio)-propionamido]hexanoate (S-LC-SPDP) was used to prepare ricin A chain (RTA) immunotoxins constructed with whole IgG and Fab fragments of the anti-common acute lymphoblastic leukemia antigen (CALLA) monoclonal antibody. In this study, a) S-LC-SPDP modification efficiencies of whole IgG and Fab, b) conjugation yields of the immunotoxins prepared and c) in vitro immunoreactivity and cytotoxicity of immunotoxins constructed were examined. IgG-RTA and Fab-RTA immunotoxins were prepared with 67.3% and 57.0% conjugation yields, respectively. These long spacer intermolecular linked immunotoxins were selectively immunoreactive and cytotoxic against to immunogenic Daudi cells but little or no-binding and cytotoxic against to antigen K562 cells. Both IgG-RTA and Fab-RTA immunotoxins were 210- and 45-fold more active than intact RTA in vitro, respectively.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D003432:Cross-Linking Reagents; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology*; D000922:Immunotoxins / Q000276:immunology / Q000633:toxicity*; D051379:Mice; D015260:Neprilysin / Q000276:immunology*; D011725:Pyridines; D012276:Ricin / Q000276:immunology*; D013386:Succinates; D014407:Tumor Cells, Cultured