Human immunology

Current research projects

• Why doesn’t everyone get type 1 diabetes?

  As a living tissue, blood holds the key to many mysteries about what is happening at a fundamental, molecular level in our body. It provides clues to how the body detects and identifies foreign visitors – and why sometimes, it gets it wrong and attacks itself.

  We want to know what is happening at a cellular level in those people – what is their body doing differently that other people’s bodies aren’t?

  To answer this question, the researchers will look at markers called human leucocyte antigens, or HLA, which everyone has on most cells of their body. Their job is to help your immune system identify your cells as your own, so that it doesn’t see them as foreign and mistakenly initiate an immune response. There are different types of HLA, but there are a few in particular the researchers would like to explore. Your blood donation will help them do that.

  For more information, please see Why doesn’t everyone get type 1 diabetes?

  What antigens do human islet infiltrating CD4+ T cells ‘see’?

  Group Leader: Associate Professor Stuart Mannering

  Team Members: Dr Pushpak Bhattacharjee, Dr Matthew Lacorcia, Eleanora Tresoldi, Miha Pakusch, Abby Foster, Elizabeth Crouch

  Collaborators:

  • Professor Tom Kay and Associate Professor Helen Thomas
  • Professor Fergus Cameron, Royal Children’s Hospital, Melbourne
  • Professor Ed Stanley, Murdoch Children’s Research Institute
  • Associate Professor Jason Tye-Din and Dr Melinda Hardy, WEHI
  • Associate Professor John Wentworth, WEHI
  • Associate Professor Dan Pellici, Murdoch Children’s Research Institute
  • Professor Jamie Rossjohn and Dr Hugh Reid, Monash University

  Genome wide association studies (GWAS) have confirmed that the strongest genetic risk for T1D is mediated by HLA alleles, specifically HLA DQ8 and DQ2. The second strongest association maps to the promoter region of the insulin gene. While these associations are well accepted in the field, it remains unclear how HLA DQ2/8 and insulin lead to type 1 diabetes. From our analysis of human islet-infiltrating CD4+ T cell clones we have identified several HLA DQ8-restricted CD4+ T cell epitopes derived from the C-peptide of proinsulin. This project will build upon this success and identified epitopes from other antigens (including GAD-65, IGRP, IAPP, ZnT8). The long-term goal is to identify common features of epitopes seen by islet infiltrating CD4+ cells. This project will examine the epitope’s affinity for the restricting HLA allele, the avidity of TCR binding and TCR usage.

   

  Do islet infiltrating CD4+ T cells recognise epitopes formed by post-translational modification?

  Group Leader: Dr Stuart Mannering

  Team Members: Vimukthi Pathiraja, Eleanora Tresoldi, Prerak Trivedi

  Collaborators:

  • Professor Tony Purcell and Dr Nadine Dudek, Monash University
  • Dr Maki Nakayama and Dr Aaron Michels, Barbara Davis Center for Childhood Diseases (USA)
  • Professor Jamie Rossjohn and Dr Hugh Reid, Monash University
  • Dr Eddie James, Benaroya Research Institute (USA)

  In 2005, we published the first description of an epitope formed by post-translational modification to be implicated in T1D (Mannering et al JEM 2005). While the concept of autoimmune responses against self-antigens that have undergone post-translational modification remains popular, this area remains largely unexplored in human studies.

  Our panel of islet-infiltrating CD4+ T cell clones are invaluable tools that allow us to determine if these cells recognise epitopes formed by post-translational modification. Our approach is to test panels of synthetic peptides that incorporate modified amino acids and determine if any of these are recognised by islet infiltrating CD4+ T cells. To date, we have identified one HLA-DQ8 restricted epitope that is formed by post-translational modification.

  Future work will screen a larger panel of peptides from other beta-cell antigens to find new epitopes formed by post-translational modification. Using our very sensitive CFSE-based proliferation assays (Mannering JIM 2003), we will measure responses to modified epitopes in PBMC from individuals with and without T1D. Our biochemical/functional analysis will also include structural analysis of TCR-peptide-HLA complex to gain insights into how human T cells ‘see’ autoantigens.

  Identifying the antigens and epitopes seen by human islet-infiltrating CD8+ T cells

  Group Leader: Dr Stuart Mannering

  Team Members: Prerak Trivedi and Eleanora Tresoldi

  Collaborators:

  • Professor Tony Purcell and Dr Nadine Dudek, Monash University
  • Professor Tom Kay, Associate Professor Helen Thomas and Dr Bala Krishnamurthy

  CD8+ T cells that recognise beta-cell antigen derived epitopes presented by HLA class I molecules are believed to the ‘killers’ that destroy the insulin-secreting beta cells. The goal of this project is to identify the antigens and epitopes ‘seen’ by human islet-infiltrating CD8+ T cells.

  We have developed a Cos cell transfection system which allows us to screen CD8+ T cell clones for responses to individual antigen/HLA combinations. This system has been validated using CD8+ T cell clones specific for viral epitopes restricted by relevant HLA alleles. Antigens that stimulate the clones will be dissected to identify the epitope(s) and HLA restriction. This information will be used to generate HLA tetramers for characterising beta cell antigen specific CD8+ T cells in human peripheral blood.

  Identifying the antigens and epitopes seen by human islet-infiltrating CD8+ T cells

  Group Leader: Dr Stuart Mannering

  Team Members: Eleanora Tresoldi

  Collaborators:

  • Dr Nadine Dudek, Monash University
  • Dr Bala Krishnamurthy

  Identification of antigens recognised by human T cells has been technically challenging. This is because relevant T-cell clones have been difficult to isolate and preparing antigen in a suitable format has been difficult. Hence the aim of this project is to develop improved techniques for identifying antigens recognised by human islet infiltrating T cells.

  We propose to genetically fuse the antigens to the Class II invariant chain that directs the protein to the lysosomes for loading into HLA Class II molecules. This project will investigate different antigen presenting cells, such as EBV transformed B cells and HLA transfected Cos cells. The capacity of the constructs to stimulate islet infiltrating CD4+ T cell clones specific for proinsulin will be used to test the system.

  This project would be suitable for an Honours student. Successfully completing this project would be an excellent preparation for a PhD project using this system to characterise human islet-infiltrating T cells.