Epitope selection in major histocompatibility complex class I-mediated pathway is affected by the intracellular localization of an antigen.
We analyzed the mode of antigen presentation of an endogenous antigen localized in the cytoplasm or in the mitochondria. Pseudomonas aeruginosa PAO leucine-, isoleucine-, valine-binding protein (LIVAT-BP) encoded by the braC gene was used as a model antigen. Using mouse BALB/3T3 cells, we established two LIVAT-BP transfectants by transfection of a plasmid harboring the intact braC or braC gene fused with the mitochondrial transport signal derived from the yeast COXIV gene. One of the resulting transfectants, BC-15, expressed LIVAT-BP in the cytoplasm, while YZ-710 cells expressed LIVAT-BP in the mitochondria. The splenic effector cells derived from BALB/c mice primed with BC-15 cells exhibited cytotoxic T lymphocyte (CTL) activity against BC-15 cells, but not against YZ-710 cells, whereas splenic effector cells primed with YZ-710 cells exhibited CTL activity against YZ-710 cells, but not against BC-15 cells. Neither group of splenic effector cells showed CTL activity against parental BALB/3T3 cells. These CTL belonged to the CD8+ alphabeta T cell subset. Furthermore, we observed that the CTL activity against t BC-15 cells or YZ-710 cells was blocked with anti-H2-K(d) mAb, but not with anti-H2-D(d) or H2-L(d) mAb. The CTL against BC-15 or YZ-710 cells could kill parental BALB/3T3 cells in the presence of peptides produced by alkali lysis of the LIVAT-BP, suggesting that these CTL indeed recognized the peptide(s) derived from LIVAT-BP. We determined that the epitope for the CTL against BC-15 cells was QYGEGIATEV, corresponding to residues 162-171, and that the epitope recognized by the CTL against YZ-710 cells was GYKLIFRTI, corresponding to residues 123-131 of LIVAT-BP, respectively. Thus, we show here that epitope selection for MHC class I expression is affected by the intracellular localization of the antigenic protein.[1]References
- Epitope selection in major histocompatibility complex class I-mediated pathway is affected by the intracellular localization of an antigen. Yamazaki, H., Tanaka, M., Nagoya, M., Fujimaki, H., Sato, K., Yago, T., Nagata, T., Minami, M. Eur. J. Immunol. (1997) [Pubmed]
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