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Immunotoxins directed against the high‐molecular‐weight melanoma‐associated antigen. Identification of potent antibody‐toxin combinations
Author(s) -
Godal Aslak,
Kumle Brita,
Pihl Alexander,
Juell Siri,
Fodstad Øystein
Publication year - 1992
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910520423
Subject(s) - immunotoxin , cytotoxicity , pseudomonas exotoxin , toxin , antigen , antibody , epitope , potency , monoclonal antibody , cell culture , microbiology and biotechnology , toxicity , in vitro , biology , exotoxin , conjugate , diphtheria toxin , chemistry , biochemistry , immunology , mathematical analysis , genetics , mathematics , organic chemistry
To study factors influencing the cytotoxicity of immunotoxins (ITs), we compared the in vitro cytotoxicity of conjugates in which the plant toxin abrin and the bacterial toxin Pseudomonas exotoxin A (PE) were coupled by 2 different procedures to 2 MAbs, 9.2.27 and NR‐ML‐05, which bind to different epitopes on the melanoma‐associated antigen p250. The individual target cell lines differed widely in sensitivity to the different ITs, as assessed by measurement of protein synthesis inhibition. The action of the ITs was highly specific, as the toxicity of abrin and PE conjugates was respectively 20–540 and 2,200–550,000 times higher in antigen‐positive cell lines (FEMX, SESX, OHS) than in the antigen‐negative line KPDX. The PE conjugates prepared with the 2 different MAbs differed in potency by factors of 16–126 in the target‐cell lines, but were consistently more toxic than the abrin ITs. The results demonstrate that the cytotoxicity of ITs varies with the nature of both of its moieties and that optimal results require that toxins and MAbs be matched. Moreover, the 2 coupling procedures affected differentially the binding and potency of some ITs. Each of the 2 toxins was conjugated to a sheep anti‐mouse antibody (SAM) and the toxicity of these 2 conjugates was tested in an indirect approach using 9.2.27 and NR‐ML‐05 as primary MAbs. The results showed that the indirect procedure would have correctly predicted the most potent antibody‐toxin pair, indicating that the approach may be valid for selecting suitable combinations of MAbs and toxins for use as direct ITs. © 1992 Wiley‐Liss, Inc.