Enhanced CD4+ T-cell response in DR4-transgenic mice to a hybrid peptide linking the Ii-Key segment of the invariant chain to the melanoma gp100(48-58) MHC class II epitope

J Immunother. Jul-Aug 2005;28(4):352-8. doi: 10.1097/01.cji.0000170362.45456.00.


Linking the Ii-Key functional group LRMK, through a simple polymethylene linker, to the melanoma gp100(48-58) MHC class II epitope significantly enhances the vaccine response to that epitope in DR4-IE transgenic mice. A homologous series of Ii-Key/gp100(46-58) hybrids was synthesized to test the influence of spacer length (between Ii-Key and the gp100(48-58) epitope) on in vivo enhancement of gp100(48-58)-specific CD4+ T-lymphocyte responses. As measured by IFN-gamma and IL-4 ELISPOT cytokine assays, the most effective vaccine hybrid was the one with a shorter linker between Ii-Key and the epitope. Mechanistic reasons for this observation are considered. This structure-activity relationship was seen with bulk and CD4+ purified T cells, and both primary and secondary in vitro restimulation assays. CFA augmented the IFN-gamma response and to a lesser extent the IL-4 response. CpG enhanced a strong IFN-gamma response, with a negligible IL-4 response. The 3- to 5-times enhancement of the total ELISPOT responses (number of spots x mean spot area) observed after vaccination with peptides consisting of an MHC class II epitope engineered into an Ii-Key hybrid indicates a potent vaccine effect. Such constructs can be applied to many diagnostic and therapeutic uses.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antigens, Differentiation, B-Lymphocyte / immunology*
  • CD4-Positive T-Lymphocytes / immunology*
  • CD4-Positive T-Lymphocytes / metabolism
  • DNA / immunology
  • Epitopes, T-Lymphocyte / immunology*
  • HLA-DR Antigens / genetics
  • HLA-DR alpha-Chains
  • HLA-DR4 Antigen / genetics*
  • HLA-DRB1 Chains
  • Histocompatibility Antigens Class II / genetics
  • Histocompatibility Antigens Class II / immunology*
  • Humans
  • Interferon-gamma / metabolism
  • Interleukin-2 / metabolism
  • Interleukin-4 / metabolism
  • Leukocytes, Mononuclear / immunology
  • Leukocytes, Mononuclear / metabolism
  • Membrane Glycoproteins / immunology*
  • Mice
  • Mice, Transgenic
  • Neoplasm Proteins / immunology*
  • Oligodeoxyribonucleotides
  • Peptide Fragments / immunology*
  • Recombinant Fusion Proteins / genetics
  • Spleen / cytology
  • Spleen / immunology
  • T-Lymphocytes, Helper-Inducer / immunology
  • T-Lymphocytes, Helper-Inducer / metabolism
  • Th1 Cells / immunology
  • Vaccination
  • gp100 Melanoma Antigen


  • Antigens, Differentiation, B-Lymphocyte
  • CpG ODN 1826
  • Epitopes, T-Lymphocyte
  • HLA-DR Antigens
  • HLA-DR alpha-Chains
  • HLA-DR4 Antigen
  • HLA-DRB1 Chains
  • Histocompatibility Antigens Class II
  • I-E-antigen
  • Interleukin-2
  • Membrane Glycoproteins
  • Neoplasm Proteins
  • Oligodeoxyribonucleotides
  • PMEL protein, human
  • Peptide Fragments
  • Pmel protein, mouse
  • Recombinant Fusion Proteins
  • gp100 Melanoma Antigen
  • invariant chain
  • Interleukin-4
  • Interferon-gamma
  • DNA