       Document 0683
 DOCN  M9630683
 TI    Sensitization of MHC class I-restricted T cells to exogenous proteins:
       evidence for an alternative class I-restricted antigen presentation
       pathway.
 DT    9603
 AU    Martinez-Kinader B; Lipford GB; Wagner H; Heeg K; Institute for Medical
       Microbiology and Hygiene, Technical; University of Munich, Germany.
 SO    Immunology. 1995 Oct;86(2):287-95. Unique Identifier : AIDSLINE
       MED/96096250
 AB    Immunization with exogenous proteins usually fails to immunize CD8+ T
       cells in vivo. Here we report that chicken ovalbumin (OVA) denatured by
       heat or sodium dodecyl sulphate (SDS) effectively induced CD8+ cytolytic
       T cells in vivo. The cytolytic T-lymphocyte (CTL) population generated
       recognized syngeneic target cells pulsed with the immunodominant OVA
       peptide (257-264) or transfected with the OVA protein-encoding gene. To
       analyse the mechanisms of how denatured OVA enters the class
       I-restricted pathway of antigen presentation, we took advantage of the
       fact that denatured OVA sensitizes target cells in vitro for lysis by
       OVA-specific CTL. We found that neither inhibition of protein synthesis
       (by cycloheximide) nor blocking of transport via the Golgi apparatus (by
       brefeldin A) interfered with the class I-restricted presentation of
       denatured OVA in vitro. In addition, transporter associated with antigen
       presentation (TAP)-dependent transport into the endoplasmic reticulum
       (ER) was not required for effective presentation, as TAP-deficient cells
       (RMA-S) could be sensitized effectively by denatured OVA for recognition
       by class I-restricted CTL. In contrast, class I-restricted presentation
       of denatured OVA was sensitive to lysosomotropic agents (NH4Cl,
       vinblastine and leupeptin), indicating that endosomal-like compartments
       are involved in the presentation of denatured OVA. Sensitization was
       inhibited at low temperature, yet took place in the presence of sucrose
       and in the absence of K+, indicating that denatured OVA enters the cell
       via fluid-phase endocytosis. Hence the results provide further evidence
       for an alternative class I-restricted pathway of antigen presentation
       for exogenous proteins. As that pathway seems to be effective in vivo,
       it offers a new and effective way of vaccination of CD8+ CTL.
 DE    Amino Acid Sequence  Animal  Antigen Presentation/*IMMUNOLOGY  Cell
       Culture  CD8-Positive T-Lymphocytes/*IMMUNOLOGY  Endocytosis/IMMUNOLOGY
       Female  Heat  Histocompatibility Antigens Class I/*IMMUNOLOGY
       Lysosomes/IMMUNOLOGY  Mice  Mice, Inbred C57BL  Molecular Sequence Data
       Ovalbumin/*IMMUNOLOGY  Protein Denaturation  Sodium Dodecyl Sulfate
       Support, Non-U.S. Gov't  JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).

