title: Modulation of immunogenicity and antigenicity of proteins by maleylation to target scavenger receptors on macrophages.
abstract: We have maleylated proteins to target macrophage-specific scavenger receptors and have used this system to study changes in the epitopes and immunogenicity of such proteins. We show that maleylation of diphtheria toxoid (DT) induces targeting to macrophage scavenger receptors and enhances its immunogenicity. DT does not evoke detectable serum Ab responses upon injection as soluble protein. However, maleylated DT (mDT) does generate a significant Ab response. Furthermore, immunization with soluble mDT leads to a better T cell proliferative response in vitro than immunization with DT can generate, thereby demonstrating that maleylation leads to enhanced T cell immunogenicity in vivo. We also find that maleylation disrupts the native B cell epitopes of DT and creates new epitopes, because antisera to DT and mDT do not cross-react. At least some of the new epitopes generated are maleylation specific, because antisera against various maleylated proteins do cross-react. In contrast, maleylation does not significantly modify the repertoire of T cell epitopes generated from DT, because T cells generated by either DT or mDT immunization are cross-reactive, and both DT and mDT can stimulate T cells that are specific for single synthetic DT peptide. Maleylated proteins are better presented in vitro than are their native counterparts, and this enhancement of presentation is blocked by unrelated maleylated proteins. These results suggest that Ags targeted to scavenger receptors on macrophages by maleylation are better presented to T cells and are immunogenic in vivo without adjuvant.
authors.affiliation: National Institute of Immunology, New Delhi, India.
authors.forename: R
authors.initials: R
authors.lastname: Abraham
authors.forename: N
authors.initials: N
authors.lastname: Singh
authors.forename: A
authors.initials: A
authors.lastname: Mukhopadhyay
authors.forename: S K
authors.initials: SK
authors.lastname: Basu
authors.forename: V
authors.initials: V
authors.lastname: Bal
authors.forename: S
authors.initials: S
authors.lastname: Rath
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D000941:Antigens / Q000737:chemistry / Q000276:immunology*; D001667:Binding, Competitive; D003429:Cross Reactions; D004168:Diphtheria Toxoid / Q000276:immunology / Q000493:pharmacokinetics; D004705:Endocytosis; D000939:Epitopes / Q000737:chemistry / Q000276:immunology; D008024:Ligands; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation; D008264:Macrophages / Q000378:metabolism*; D008298:Maleates / Q000378:metabolism*; D008565:Membrane Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin / Q000276:immunology; D011506:Proteins / Q000737:chemistry / Q000276:immunology / Q000493:pharmacokinetics*; D011947:Receptors, Antigen, B-Cell / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D011971:Receptors, Immunologic / Q000378:metabolism*; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D051122:Scavenger Receptors, Class B; D012710:Serum Albumin, Bovine / Q000493:pharmacokinetics; D013745:Tetanus Toxoid / Q000276:immunology / Q000493:pharmacokinetics
chemical_list: D000941:Antigens; D004168:Diphtheria Toxoid; D000939:Epitopes; D008024:Ligands; D008298:Maleates; D008565:Membrane Proteins; D011506:Proteins; D011947:Receptors, Antigen, B-Cell; D011948:Receptors, Antigen, T-Cell; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; C454739:Scarb1 protein, mouse; D051122:Scavenger Receptors, Class B; D013745:Tetanus Toxoid; D012710:Serum Albumin, Bovine; D010047:Ovalbumin; C030272:maleic acid