Antigen Presentation by MHC Class I and CD1 Molecules

Gadola, Stephan D. (2009). Antigen Presentation by MHC Class I and CD1 Molecules. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000f26e

Abstract

Antigen presentation is the “sine qua non” of the mammalian adaptive immune system. The assembly of MHC class I/peptide complexes in the endoplasmic reticulum (ER) relies on the orchestrated interplay between different chaperonins, which assist MHC class I folding, and the peptide loading complex (PLC). Mutant lymphoblastoid cell lines with defective MHC class I surface expression have greatly helped the functional analysis of the PLC. The TAP transporter associated with antigen processing translocates MHC class I peptide ligands from the cytosol into the ER and is critical for successful MHC class I assembly and maturation. In the first two results chapters of this thesis I will describe the identification, clinical description and molecular and genetic analysis of a new clinical syndrome in a group of patients with dramatically reduced MHC class I surface expression. The disease in these patients could be identified as primary TAP-deficiency.

Mycobacterial infections were conspicuously absent in these TAP-deficient patients whereas TAP-deficient mice are known to be highly susceptible to mycobacteria. The focus of the third and fourth chapter of this thesis lies on lipid antigen presentation via CD1 molecules, which are known to present mycobacterial lipids to T lymphocytes. The first objective of this thesis was to generate recombinant mycobacterial lipid loaded CD1 molecules as tools to measure mycobacterial lipid specific T cell responses in the TAP-deficient patients. Chapters three and four describe novel protocols for the generation of recombinant human CD 1b and CD 1d molecules with loaded single lipid species.