title: Monoclonal antibodies to purified ricin A-chain: production and properties.
abstract: Ricin A-chain was purified from native ricin using lactosyl-Sepharose. It was non-toxic to whole cells at a concentration of 1 microM yet nearly as effective as an equimolar concentration of ricin in blocking in vitro protein synthesis. Hybridomas secreting monoclonal antibodies to ricin A-chain were produced using the murine myeloma cell line NS-1. These anti-ricin A-chain antibodies cross-reacted with whole ricin but exhibited little cross-reactivity with purified ricin B-chain. Antibodies 2F2 and 2F5 both immunoprecipitated ricin A-chain. Both antibodies also precipitated ricin B-chain, as did the irrelevant control antibodies MOPC-21 and MPC-11. Pre-incubation of B-chain with 0.1 M galactose eliminated greater than 90% of precipitation by 2F2, MOPC-21 and MPC-11 but effected minimally precipitation by 2F5. Enzyme-linked immunosorbent assays using antibodies 2F2 and 2F5 to detect ricin A-chain in murine or human serum were linear between 40 and 800 ng ricin A-chain per ml. Anti-ricin A-chain antibodies 2F2 and 2F5 produced some inhibition of in vitro A-chain catalytic activity. Specific monoclonal antibodies to A-chain hemitoxin will be useful for characterization of functional hemitoxin domains, in in vitro assays for the stability of A-chain immunotoxins, and in characterizing the cellular internalization and processing of conjugates containing ricin or ricin A-chain.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D011232:Chemical Precipitation; D004586:Electrophoresis; D046911:Macromolecular Substances; D051379:Mice; D008970:Molecular Weight; D014176:Protein Biosynthesis / Q000187:drug effects; D012276:Ricin / Q000276:immunology* / Q000633:toxicity
chemical_list: D000911:Antibodies, Monoclonal; D046911:Macromolecular Substances; D012276:Ricin