IL-4, in the presence of macrophages (MΦs), has previously been demonstrated to be tumoricidal in vitro and in vivo, possibly through MΦ activation. In the current study, the biological activities of murine IL-4 on MΦs, and the initial identification of signal transduction mechanisms in IL-4-mediated MΦ activation were determined. Hamster MΦ were activated with IL-4 to study MΦ tumoricidal activity against hamster pancreatic adenocarcinoma in vivo.Through this initial study, it was observed that murine IL-4 is species specific and incapable of crossing the narrow phylogenetic barrier to hamster and perhaps rat (partially). The effects of murine IL-4 on allogeneic peritoneal and bone marrow-derived (14M1 .4 cell line) MΦ were then evaluated. Results showed a marked, dose-dependent stimulation of chemiluminescent oxidative burst by IL-4- activated MΦs, an activity which was IL-4 monoclonal antibody reversible. In addition, it appeared that 14M1.4 MΦ were more responsive than peritoneal MΦs to IL-4 in that they responded quicker and released greater quantities of reactive oxygen intermediates. Based on this preliminary work, the 14M14.4 MΦs were used to study the yet unknown signal transduction mechanisms in IL-4-mediated MΦ activation. By means of flow cytometric techniques and the membrane potential sensitive dye, DIOC6(3), it was shown that IL-4 caused no apparent biological but a statistically significant change in the membrane potential of MΦs. Using flow cytometry and indo-1AM, it was determined that intracellular calcium levels changed. An optimal concentration of 1L-4 caused a rapid increase in the initial (inhibited by BAPTA-AM, a specific intracellular chelator of calcium) and then sustained (inhibited by EGTA) level of intracellular calcium. Through assessments of chemiluminescence oxidative burst activity, it was demonstrated that the initial and sustained increase in intracellular calcium was required and important for IL-4 enhancement of the oxidative burst by 14M1.4 MΦs. Increase in production of IP3 but no change in levels of cAMP, immediate or delayed, were demonstrated using competitive binding assays. These findings were further supported by the fact that cholera toxin and prostaglandin E2 (agents which increase cAMP), did not enhance chemiluminescence, nor did PMA, a potent activator of PKC. Surprisingly, IL-4-stimulated MΦ were not cytolytic to tumor cell targets; yet, IL-4 was directly cytostatic to some of the same cell lines.
Sandra L. Nehlsen-Cannarella
Christopher D. Cain
Benjamin H. S. Lau
Thomas A. Linkhart
Doctor of Philosophy (PhD)
Year Degree Awarded
Date (Title Page)
Library of Congress/MESH Subject Headings
Interleukin-4 -- analysis; Macrophages -- immunology; Biological Assay -- methods; Cytotoxicity, Immunologic -- physiology; Pancreatic Neoplasms -- therapy
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Tan, Henkie Pierre, "Characterization of Murine Interleukin-4 (IL-4) : Biological Activities and Initial Identification of Signal Transduction Mechanisms in IL-4-Mediated Macrophage Activation" (1992). Loma Linda University Electronic Theses, Dissertations & Projects. 1650.
Loma Linda University Electronic Theses and Dissertations
Loma Linda University. Del E. Webb Memorial Library. University Archives