This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Westcott, M. M. Articles by Frankel, A. E. Search for Related Content PubMed PubMed Citation Articles by Westcott, M. M. Articles by Frankel, A. E.

Departments of ¹ Internal Medicine, ² Biochemistry and ³ Pathology, Wake Forest University School of Medicine, Winston-Salem, North Carolina; ⁴ Microbial Pathogenesis Section, National Institute of Allergy and Infectious Diseases; and ⁵ Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, NIH, Bethesda, Maryland

Requests for reprints: Arthur E. Frankel, Wake Forest University School of Medicine, Internal Medicine, Hematology/Oncology, Hanes 5045, Medical Center Boulevard, Winston-Salem, NC 27157. Phone: 336-716-3313; Fax: 336-716-9113. E-mail: afrankel{at}wfubmc.edu

DT₃₈₈GMCSF, a fusion toxin composed of the NH₂-terminal region of diphtheria toxin (DT) fused to human granulocyte-macrophage colony-stimulating factor (GMCSF) has shown efficacy in the treatment of acute myeloid leukemia. However, the primary dose-limiting side effect is liver toxicity. We have reproduced liver toxicity in rats using the rodent cell-tropic DT-murine GMCSF (DT₃₉₀mGMCSF). Serum aspartate aminotransferase and alanine aminotransferase were elevated 15- and 4-fold, respectively, in DT₃₉₀mGMCSF-treated rats relative to controls. Histologic analysis revealed hepatocyte swelling; however, this did not lead to hepatic necrosis or overt histopathologic changes in the liver. Immunohistochemical staining showed apoptotic cells in the sinusoids, and depletion of cells expressing the monocyte/macrophage markers, ED1 and ED2, indicating that Kupffer cells (KC) are targets of DT₃₉₀mGMCSF. In contrast, sinusoidal endothelial cells seemed intact. In vitro, DT₃₉₀mGMCSF was directly cytotoxic to primary KC but not hepatocytes. Two related fusion toxins, DT₃₈₈GMCSF, which targets the human GMCSF receptor, and DT₃₉₀mIL-3, which targets the rodent IL-3 receptor, induced a less than 2-fold elevation in serum transaminases and did not deplete KC in vivo. In addition, DTU2mGMCSF, a modified form of DT₃₉₀mGMCSF with enhanced tumor cell specificity, was not hepatotoxic and was significantly less toxic to KC in vivo and in vitro. These results show that DT₃₉₀mGMCSF causes liver toxicity by targeting KC, and establish a model for studying how this leads to hepatocyte injury. Furthermore, alternative fusion toxins with potentially reduced hepatotoxicity are presented.

Key Words: diphtheria toxin • GMCSF receptor • fusion toxin • Kupffer cell • hepatotoxicity

Grant support: NIH grants RO1CA76178 and RO1CA90263(A.E. Frankel).

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

⁶ Westcott and Frankel, unpublished data.

Received 6/30/04; revised 8/18/04; accepted 8/27/04.