Protein A vectorized toxins--II. Preparation and "in vitro" cytotoxic effect of protein A-ricin A chain conjugate on antibody coated human tumour cells.
Protein A of Staphylococcus aureus was covalently bound to reduced ricin A chain toxin by N-succinimidyl 3-(2-pyridyldithio)propionate. The conjugate consisting mainly of one molecule of protein A bound to two molecules of A chains (Mr 107,000) was purified by tandem affinity chromatography on ConA-Sepharose 4B and IgG-Sepharose 4B. The purified protein A-A chain conjugate was able to bind and kill human lymphoma cells coated either with monoclonal mouse IgG2a anti-kappa antibody or with polyclonal rabbit anti-kappa antibody. The cytotoxic activity of protein A-A chain conjugate in conjunction with either mouse or rabbit anti-kappa antibodies was 10 times higher than that of rabbit IgG anti-mouse IgG coupled with A chain on Daudi cells coated with mouse anti-kappa antibody and 100 times higher than that of rabbit anti-kappa antibody coupled with A chain on non-coated Daudi cells. The cytotoxic effect of protein A-A chain conjugate on antibody-coated Daudi cells (9 x 10(-12) M) was comparable with that of ricin toxin on non-coated Daudi cells (2 x 10(-12) M). The results recommend the use of protein A-ricin A chain toxin conjugate as a unique specific toxin for the "in vitro" killing of antibody-coated target cells.
Ghetie
M A
MA
Laboratory of Immunochemistry, Babes Institute, Bucharest, Romania.
Moraru
I
I
Margineanu
M
M
Ghetie
V
V
D002051:Burkitt Lymphoma / Q000378:metabolism / Q000473:pathology*; D002470:Cell Survival; D002846:Chromatography, Affinity; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D012276:Ricin / Q000494:pharmacology*; D013205:Staphylococcal Protein A / Q000378:metabolism / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D007074:Immunoglobulin G; D013205:Staphylococcal Protein A; D012276:Ricin