Interleukin 4 receptor targeted cytotoxicity: Genetic construction and in vivo immunosuppressive activity of a diphtheria toxin‐related murine interleukin 4 fusion protein

Abstract

The interleukin 4 (IL 4) receptor is expressed on various cells of the immune system, including T and B lymphocytes, macrophages and mast cells. We have constructed a recombinant protein, DAB389-mIL 4, that is composed of the enzymatically active and membrane translocation domains of diphtheria toxin fused to murine IL 4. We demonstrate that this fusion toxin selectively inhibits protein synsthesis in eukaryotic cells which express the murine IL 4 receptor. The cytotoxic potency of this fusion toxin is shown to be directly proportional to the reported number of IL 4 receptors on the surface of target cells. Since the action of DAB389-mIL 4 can be blocked with either excess mIL 4 or antibody to mIL 4, we conclude that its entry into target cells is mediated through the mIL 4 receptor. A mutant form of DAB389-mIL 4, DA(197)B389-mIL 4, in which the fragment A-associated ADP-ribosyltransferase is inactive, is not cytotoxic to murine IL 4 receptor-bearing cells. Finally, we demonstrate that DAB389-mIL 4 administered subcutaneously to DBA/2 mice results in suppression of delayed-type hypersensitivity (DTH); whereas, the non-toxic DA(197)B389-mIL 4 fails to dampen the DTH response.

Does Diphtheria Toxin Have Nuclease Activity?

“…3) DNase activity has not been found in cloned fragment A or fragment A-containing fusion gene products (Table 1) isolated from E. coli (10)(11)(12)(13)(14). 5) Mutant C. diphtheriae strains that cannot synthesize a secretable DNase can still be fully toxigenic (9), and certain strains of nontoxigenic C. diphtheriae secrete DNase into the culture medium.…”

Bladder carcinomas and normal urothelium universally express gp200-MR6, a molecule functionally associated with the interleukin 4 receptor (CD 124)

“…These observations indicate that IL-4 may play a role in maintaining the integrity of transitional epithelium even in its neoplastic state and that gp200-MR6 expression is unlikely to be useful in predicting the biological behaviour of bladder tumours. Moreover, while it should be possible to use antibodies such as MR6 with radioisotopic tags for visualisation of primary and metastatic disease in urothelial carcinomas, as previously shown for the lung, the presence of IL-4R on normal epithelia would argue against the use of chimaeric toxin -IL-4 conjugates to target IL-4R positive tumours because of the risks of epithelial damage (Al Jabaari et al, 1989;Lakkis et al, 1991;Debinski et al, 1993).…”

GM-CSF receptor targeted treatment of primary AML in SCID mice using Diphtheria toxin fused to huGM-CSF

“…The schedule of prolonged delivery of growth factor toxins showed fewer side-effects while it retained a maximal antileukemic effect. [42][43][44][45] In addition, a treatment duration of 7 days is conventional in human AML treatment and has been shown to be adequate for AML tumor reduction by cytostatic drugs. Lower doses of drugs are, in general, better tolerated and the duration of the treatment can thus be extended without an increased risk of treatment-related toxicity.…”