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Critical Reviews™ in Immunology

Impact factor: 3.698

ISSN Print: 1040-8401
ISSN Online: 2162-6472

Critical Reviews™ in Immunology

DOI: 10.1615/CritRevImmunol.v17.i1.10
pages 1-32

Functions of IL-4 and Control of Its Expression

Melissa A. Brown
Department of Experimental Pathology and Graduate Program in Immunology and Molecular Pathogenesis, Emory University School of Medicine, Atlanta, GA 30322
John Hural
Department of Experimental Pathology and Graduate Program in Immunology and Molecular Pathogenesis, Emory University School of Medicine, Atlanta, GA 30322

ABSTRACT

IL-4 has been called the "prototypic immunoregulatory cytokine." Like many cytokines, it can affect a variety of target cells in multiple ways. IL-4 has an important role in regulating antibody production, hematopoiesis and inflammation, and the development of effector T-cell responses. It is produced only by a subset of activated hematopoietic cells, including T cells and FcεRl+ mast cells and basophils. Based on the different tissue distribution and access to distinct target cells, IL-4 derived from T and FcεRl+ cells may have quite different effects on these immunological processes. In view of this, as well as the clear correlation of aberrant expression with disease, it is of interest to understand the signals that regulate IL-4 expression in a cell-specific manner. Recently, progress has been made in defining the T-cell- and FcεRl-receptor-mediated signals that stimulate IL-4 gene expression. These studies have demonstrated that there are common and cell-specific signaling pathways that regulate production of this cytokine. In this review, we summarize the activities of IL-4 defined both in vitro and in vivo and compare the signals leading to IL-4 expression in cells of both T- and mast-cell lineage.