Here's the abstract. I know Andy Saxon, which means that he's been around UCLA forever.......
Nat Med 2002 May;8(5):518-21
A novel human immunoglobulin Fcgamma Fcvarepsilon bifunctional fusion protein inhibits FcvarepsilonRI-mediated degranulation.
Zhu D, Kepley CL, Zhang M, Zhang K, Saxon A.
[1] The Hart and Louise Lyon Laboratory, Division of Clinical Immunology/Allergy, Department of Medicine, University of California Los Angeles School of Medicine, Los Angeles, California, USA [2] D.Z. and C.L.K. contributed equally to this study.
Human mast cells and basophils that express the high-affinity immunoglobulin E (IgE) receptor, Fcvarepsilon receptor 1 (FcvarepsilonRI), have key roles in allergic diseases. FcvarepsilonRI cross-linking stimulates the release of allergic mediators. Mast cells and basophils co-express FcgammaRIIb, a low affinity receptor containing an immunoreceptor tyrosine-based inhibitory motif and whose co-aggregation with FcvarepsilonRI can block FcvarepsilonRI-mediated reactivity. Here we designed, expressed and tested the human basophil and mast-cell inhibitory function of a novel chimeric fusion protein, whose structure is gammaHinge-CHgamma2-CHgamma3-15aa linker-CHvarepsilon2-CHvarepsilon3-CHvarepsilon4. This Fcgamma Fcvarepsilon fusion protein was expressed as the predicted 140-kappaD dimer that reacted with anti-human varepsilon- and gamma-chain specific antibodies. Fcgamma Fcvarepsilon bound to both human FcvarepsilonRI and FcgammaRII. It also showed dose- and time-dependent inhibition of antigen-driven IgE-mediated histamine release from fresh human basophils sensitized with IgE directed against NIP (4-hydroxy-3-iodo-5-nitrophenylacetyl). This was associated with altered Syk signaling. The fusion protein also showed increased inhibition of human anti-NP (4-hydroxy-3-nitrophenylacetyl) and anti-dansyl IgE-mediated passive cutaneous anaphylaxis in transgenic mice expressing human FcvarepsilonRIalpha. Our results show that this chimeric protein is able to form complexes with both FcvarepsilonRI and FcgammaRII, and inhibit mast-cell and basophil function. This approach, using a Fcgamma Fcvarepsilon fusion protein to co-aggregate FcvarepsilonRI with a receptor containing an immunoreceptor tyrosine-based inhibition motif, has therapeutic potential in IgE- and FcvarepsilonRI-mediated diseases. |
