Biochemical, cytotoxic and pharmacokinetic properties of an immunotoxin composed of a mouse monoclonal antibody Fib75 and the ribosome-inactivating protein alpha-sarcin from Aspergillus giganteus.
An immunotoxin was synthesized by the attachment of alpha-sarcin, the ribosome-inactivating protein derived from the mould Aspergillus giganteus, to a monoclonal mouse IgG2 antibody Fib75. The alpha-sarcin immunotoxin exerted toxic effects in tissue culture against the EJ human bladder carcinoma cell line, expressing the antigen recognised by the Fib75 antibody, inhibiting the incorporation of [3H]leucine by 50% at a concentration of 0.46 nM. The cytotoxic effects of the alpha-sarcin immunotoxin were indistinguishable from those of a Fib75 immunotoxin made with ricin A chain. Fib75-alpha-sarcin was cleared from the circulation of the rat with biphasic kinetics following intravenous administration. The alpha- and beta-phase half-lives were 0.8 h and 6 h, respectively, similar to the serum half-lives of analogous Fib75 immunotoxins made with ribosome-inactivating proteins derived from plants. alpha-Sarcin was completely stable in physiological saline buffer at 37 degrees C, whereas the ribosome-inactivating activity of ricin A chain was gradually lost under identical conditions. alpha-Sarcin may be a valuable alternative to ricin A chain for the construction of therapeutic immunotoxins because of its smaller size and greater thermostability.
Wawrzynczak
E J
EJ
Institute of Cancer Research, Sutton, England.
Henry
R V
RV
Cumber
A J
AJ
Parnell
G D
GD
Derbyshire
E J
EJ
Ulbrich
N
N
D000818:Animals; D000911:Antibodies, Monoclonal; D001230:Aspergillus / Q000032:analysis*; D004355:Drug Stability; D004722:Endoribonucleases; D005656:Fungal Proteins / Q000493:pharmacokinetics / Q000494:pharmacology*; D006358:Hot Temperature; D000922:Immunotoxins / Q000493:pharmacokinetics / Q000494:pharmacology*; D051379:Mice; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D012270:Ribosomes / Q000187:drug effects*; D012276:Ricin / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000187:drug effects
D000911:Antibodies, Monoclonal; D005656:Fungal Proteins; D000922:Immunotoxins; D011500:Protein Synthesis Inhibitors; C014801:alpha-sarcin; D012276:Ricin; D004722:Endoribonucleases