title: CD83 is a dimer: Comparative analysis of monomeric and dimeric isoforms.
abstract: Recently, we reported that soluble CD83 has a strong immunosuppressive activity in vitro as well as in vivo. Sequence alignment of CD83 between different species revealed the presence of five cysteines in the extracellular Ig-domain of the protein. This opens up the possibility that four cysteines are involved in the formation of two intramolecular disulfide bonds and a possible involvement of the remaining fifth cysteine in the formation of an intermolecular covalent disulfide bond, leading to the dimerization of the extracellular protein domains. Using recombinant mutational analyses, where the fifth cytosine at amino acid position 129 was mutated to a serine, we could prove that the fifth cysteine residue was indeed necessary for the dimerization. Functional analyses revealed that the mutant protein inhibited almost completely the upregulation of CD83-expression during DC maturation. Furthermore, the functional activity of the mutant protein was investigated using MLR assays and we could show that the mutant soluble CD83 protein inhibited DC-mediated allogeneic T-cell stimulation in vitro.
authors.affiliation: University Hospital Erlangen, Department of Dermatology, Hartmannstr. 14, D-91052 Erlangen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Lechmann
authors.forename: Nicole
authors.initials: N
authors.lastname: Kotzor
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Zinser
authors.forename: Alexander T
authors.initials: AT
authors.lastname: Prechtel
authors.forename: Heinrich
authors.initials: H
authors.lastname: Sticht
authors.forename: Alexander
authors.initials: A
authors.lastname: Steinkasserer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD; D015153:Blotting, Western; D049109:Cell Proliferation; D002469:Cell Separation; D003001:Cloning, Molecular; D019992:Databases as Topic; D003713:Dendritic Cells / Q000166:cytology; D019281:Dimerization; D004220:Disulfides; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D015151:Immunoblotting; D007136:Immunoglobulins / Q000096:biosynthesis / Q000737:chemistry*; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000737:chemistry*; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D012984:Software; D013045:Species Specificity; D020349:Surface Plasmon Resonance; D013601:T-Lymphocytes / Q000276:immunology; D015854:Up-Regulation; D000097802:CD83 Antigen
chemical_list: D015703:Antigens, CD; D004220:Disulfides; D007136:Immunoglobulins; D008562:Membrane Glycoproteins; D000097802:CD83 Antigen