Minor structural changes in a mutated human melanoma antigen correspond to dramatically enhanced stimulation of a CD4+ tumor-infiltrating lymphocyte line.
Primary Citation of Related Structures: 1KLG, 1KLU
PubMed Abstract:
While most immunotherapies for cancer have focused on eliciting specific CD8+ cytotoxic T lymphocyte killing of tumor cells, a mounting body of evidence suggests that stimulation of anti-tumor CD4+ T cell help may be required for highly effective therapy ...
While most immunotherapies for cancer have focused on eliciting specific CD8+ cytotoxic T lymphocyte killing of tumor cells, a mounting body of evidence suggests that stimulation of anti-tumor CD4+ T cell help may be required for highly effective therapy. Several MHC class II-restricted tumor antigens that specifically activate such CD4+ helper T lymphocytes have now been identified, including one from a melanoma tumor that is caused by a single base-pair mutation in the glycolytic enzyme triosephosphate isomerase. This mutation results in the conversion of a threonine residue to isoleucine within the antigenic epitope, concomitant with a greater than five log-fold increase in stimulation of a CD4+ tumor-infiltrating lymphocyte line. Here, we present the crystal structures of HLA-DR1 in complex with both wild-type and mutant TPI peptide antigens, the first structures of tumor peptide antigen/MHC class II complexes recognized by CD4+ T cells to be reported. These structures show that very minor changes in the binding surface for T cell receptor correspond to the dramatic differences in T cell stimulation. Defining the structural basis by which CD4+ T cell help is invoked in an anti-tumor immune response will likely aid the design of more effective cancer immunotherapies.
Related Citations:
Biochemical identification of a mutated human melanoma antigen recognized by CD4+ T cells Pieper, R., Christian, R.E., Gonzales, M.I., Nishimura, M.I., Gupta, G., Settlage, R.E., Shabanowitz, J., Rosenberg, S.A., Hunt, D.F., Topalian, S.L. (1999) J Exp Med 189: 757
Organizational Affiliation:
Center for Advanced Research in Biotechnology, W. M. Keck Laboratory for Structural Biology, University of Maryland Biotechnology Institute, 9600 Gudelsky Drive, Rockville, MD 20850, USA. sundberg@umbi.umd.edu
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