Enhancement of human IL-4 activity by soluble IL-4 receptors in vitro.
The recombinant form of the extracellular domain of the IL-4 receptor (sIL-4R) is a potential candidate to neutralize IL-4; however, murine sIL-4R displayed both antagonistic and agonistic activity in vivo. Here we show that human recombinant sIL-4R induced the formation of complexed IL-4 in supernatants of activated T cells in a dose-dependent manner as measured by newly developed enzyme-linked immunosorbent assays. These IL-4/sIL-4R complexes liberated free IL-4 even after prolonged culturing. In contrast, in the absence of exogenously added sIL-4R, free IL-4 was rapidly consumed or proteolytically degraded in cultures of activated T cells. Thus, no IL-4 bioactivity could be determined in supernatants of T cells activated in the presence of IL-4 for 6 days. In contrast, the same cultures carried out in the presence of sIL-4R showed marked IL-4 bioactivity. While low concentrations of sIL-4R enhanced IL-4-driven inhibiton of IFN-gamma production by activated T cells, higher concentrations neutralized IL-4. Together, human sIL-4R, besides its activity as an antagonist to IL-4, also possesses protective and agonistic functions for IL-4, which may be relevant for clinical studies aiming to neutralize IL-4 in vivo.
Jung
T
T
Department of Dermatology, University of Göttingen, Germany. Thomas.Jung@Pharma.Novatis.Com
Wagner
K
K
Neumann
C
C
Heusser
C H
CH
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D010450:Endopeptidases / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D015847:Interleukin-4 / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D019948:Receptors, Interleukin-4 / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology; D012995:Solubility; D013601:T-Lymphocytes / Q000276:immunology
D019948:Receptors, Interleukin-4; D011994:Recombinant Proteins; D015847:Interleukin-4; D010450:Endopeptidases