Peptide transporter-independent,stress protein-mediated endosomal processing of endogenous protein antigens for major histocompatibility complex class I presentation |
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Authors: | Reinhold Schirmbeck,J rg Reimann |
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Affiliation: | Reinhold Schirmbeck,Jörg Reimann |
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Abstract: | The peptide transporter-defective cell line RMA-S expressing the wild-type simian virus 40 large T antigen (wtT-Ag) from a transfected gene did not present two well-defined, H-2 class I (Db)-restricted epitopes of T-Ag to cytotoxic T lymphocytes (CTL). Hence, “endogenous” processing and presentation of the wtT-Ag depended on a functional peptide transporter heterodimer. In contrast, both T-Ag epitopes were efficiently presented to CTL by transfected RMA-S cells expressing a truncated, cytoplasmic T-Ag variant (cT-Ag) or a karyophilic, amino-terminal 272-amino acid T-Ag fragment. Transporter-independent “endogenous” processing of mutant T-Ag molecules correlated with their association with the constitutively expressed heat shock protein 73 (hsp 73). Class I-restricted presentation of both epitopes processed from these hsp73-associated protein antigens was sensitive to NH4Cl and chloroquine. These data indicate that selected intracellular proteins access an alternative, hsp73-mediated pathway for class I-restricted presentation that operates independent of peptide transporters in an endosomal compartment. |
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Keywords: | Endogenous antigen processing CD8+ cytotoxic T lymphocyte triggering Antigen presentation Major histocompatibility complex class I |
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