Unit: Antiviral Cell Immunology

Director: François Lemonnier

The work of the laboratory aims, by producing genetically modified strains of mice (H-2 class I or class II knock-out mice, HLA class I or class II transgenic mice) at a) the analysis of the mechanisms involved in the education, the peripheral mobilization and the maintenance of cytolytic CD8+, helper CD4+ T lymphocytes and Natural Killer (NK) cells, b) the identification of viral or tumoral peptides presented to cytolytic and helper T lymphocytes, and c) the evaluation and optimization of their vaccine potential.

Creation of new HLA class I/class II transgenic, H-2 class I/class II KO strains of mice (Y.C. Lone, A. Pajot).

Strains of mice expressing HLA-A02.01 or HLA-A24.02 molecules in a H-2 class I KO context have been derived. The efficiency with which the mouse cytolytic CD8+ T lymphocytes use these molecules for the recognition of antigens is under evaluation. Similarly, strains of mice expressing either HLA-A02.01 and HLA-DR1, or HLA-A02.01 and HLA-DR3, or HLA-A02.01 and HLA-DQ8 on a H-2 class I/class II KO context have been obtained. These strains of mice will be used for the preclinical evaluation of the adaptive immune responses (antibody, CD8+ cytolysis and CD4+ help) to vaccine candidates of preventive or therapeutical interest for humans.

Vaccine potential of HLA-A0201- and HLA-B702-restricted epitopic peptides of HIV 1 origin (P. Langlade-Demoyen, S. Cardinaud, P. Rohrlich)

The vaccine potentials of HIV 1-derived epitopic peptides reported in the literature or identified in the laboratory have been compared using transgenic mice expressing HLA-A02.01 molecules in the complete absence of H-2 class I molecules or the HLA-B07.02 molecules in a H-2Kb, H-2Db double KO context. Following these studies, it was possible to establish a hierarchy in terms of immunogenicity of these peptides, to optimize the immunogenicity of those which were poorly immunogenic in their native configuration, to compare vaccine strategies and to demonstrate that a polyepitope construct could induce multiepitopic, long-lasting cytolytic responses in a single mouse. Two polyepitopes (HLA-A02.01, -B07.02) have been constructed. A third one will be realized in the coming year corresponding to the HLA-A3.01 molecule, using a new transgenic strain of mice.

Exploitation of HLA-class I transgenic, H-2 class I KO and HLA class II transgenic, H-2 class II KO mice (A. Pajot, Y.C. Lone)

HLA class II transgenic (DPß401, DPα 103) H-2 class II KO mice have been created and used to identify HBV-derived epitopic peptides presented by HLA-DPß401.α 103 molecules which are expressed by > than 50% of individuals in human populations. Similar studies will be extended to HIV 1. Similarly, transgenic (HLA-A02.01, HLA-DR) H-2 class I class II KO mice have been derived. These animals will be used to evaluate preclinically and simultaneously all components of the immune adaptive responses (CD8+ cytolytic, CD4+ helper and antibody) to vaccine formulations of potential interest in humans and the protection confered.

Recognition by CD8+ cytolytic T lymphocytes of histocompatibililty molecules deprived of antigen presention function (P. Rohrlich).

Cytolytic CD8+ T lymphocytes recognize short antigenic peptides bound to histocompatibility molecules in their peptide binding pocket. Immunizing mice deficient in Hfe molecules (a molecule which regulates iron metabolism, has an overall structure similar to that of " classical " histocompatibility molecules but has no ligand in its peptide binding pocket) cytolytic CD8+ T lymphocytes were stimulated that recognize directly Hfe. Thus, the presence of a ligand in the peptide binding pocket of histocompatibility molecules is not an absolute requirement for their recognition by the T cell receptor (TcR) for antigen. Direct recognition of Hfe results from the preferential mobilization of a subset of CD8+ T lymphocytes with predominant usage of a defined variable segment of the TcR α chain. This subset of CD8+ T lymphocytes might therefore participate in the regulation of iron metabolism.

Genes controlling NK cell differentiation (C. Roth)

Using stable NK cell lines and clones derived from P53 deficient mice, two complementary approaches have been used to identify new receptors and co-receptors potentially involved in NK cell maturation. A differential expression library was prepared from clones either highly or poorly cytotoxic. Among the different cDNA isolated, we are focusing on one corresponding to a receptor. Strains of mice deficient in this receptor exhibit a profound defect in bone-marrow maturation of NK cells.

Keywords: HLA Transgenic, H-2 KO mice, HIV 1, Hfe, NK

Activity Reports 2004 - Institut Pasteur

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