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ProImmune Antigen Characterization Summit Paul Moss
 

ProImmune Antigen Characterization Summit Paul Moss

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Paul Moss, School of Cancer Sciences, Birmingham UK, presents at the ProImmune Antigen Characterization and Biomarker Discovery Summit, January 2011.

Paul Moss, School of Cancer Sciences, Birmingham UK, presents at the ProImmune Antigen Characterization and Biomarker Discovery Summit, January 2011.
Cytomegalovirus and Cancer-specific Immunity

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  • If an antigen which had been labelled, for instance with a fluorescent dye, could be directly bound to T cells then the antigen-specific cells could be detected directly.
  • Once these complexes are made they can bind to a T cell specific for the peptide which was been inserted in the multimeric complex and then these T cells can be detected on a FACS machine by the fluoresecnce that they emit.
  • Once these complexes are made they can bind to a T cell specific for the peptide which was been inserted in the multimeric complex and then these T cells can be detected on a FACS machine by the fluoresecnce that they emit.

ProImmune Antigen Characterization Summit Paul Moss ProImmune Antigen Characterization Summit Paul Moss Presentation Transcript

  • Cytomegalovirus and cancer-specific immunity – lessons from across the spectrum of immunodominance Paul Moss School of Cancer Sciences
  • Overview
    • Immunology of Cytomegalovirus
      • Immune control in immune competent and immune suppressed donors
      • Immunotherapy
    • Cancer Immunology
      • Cancer testis antigens
  • - HIV+ donors - Cloned HIV-specific CTL - Cloned TCR - cDNA from PBMC was probed with oligos for TCRs - Suggested effector frequency of 0.2 - 1%
  • Led to collaboration on use of new reagents to study T cell immune responses Viral Antigen Fluorescence T Cell
  • We could visualise HIV-specific T cells Altman, Moss et al Science. 1996 Oct 4;274(5284):94-6.Phenotypic analysis of antigen-specific T lymphocytes.
  • Then used cytomegalovirus as a ‘control’ for HIV
    • … but the immune response was bigger than HIV
  • Herpes viruses Group of eight viruses HSV I & II, EBV, VZV, CMV, HHV-6 HHV-7, HHV-8
  • CMV infection is very common
  • CMV natural history
    • CMV has evolved to co-exist with an immunocompetent host
    • CMV is poorly adapted to live with an immunosuppressed host
      • transplant recipients
      • HIV infection
  • CMV latency appears to be the result of chronic immune control Antibody NK cells T cells
  • T cell immunity in healthy donors
  • The CD8+ T cell response to CMV
  • Age Percentage of CD8+ T cell response Khan et al , J.I. 2004 The CD8-specific T cell response to CMV increases with age DE F P=0.0352 P0.0067 P=0.0159 P=0.07262 P=0.003
  • How does CMV change the memory and naïve T cell count in healthy people ? T cells Naive Memory
  • The CD8+ memory T cell count is stable with age
  • CMV greatly increases the number of memory T cells
  • The CD8+ naïve T cell count declines with age
  • CMV reduces the naïve cell count at all ages
  • CMV seropositivity at age 50 years accelerates naïve T cell decline by 25 years
  • The immune response to CMV is massive
    • CD8: 2 - 40% of T cells
    • CD4: 2 - 10% of T cells
    Time (years) Magnitude of T cell immunity CMV
  • The clinical implications of CMV infection
  • Primary infection Time (years) Magnitude of T cell immunity
  • Sometimes the initial (primary) infection with CMV can cause clinical problems “ I though it was the end of my tennis. Even as a person I could feel myself changing. I just wanted to stay and home and not see anyone, not even my friends. But slowly I got better. I still have to be careful and I can’t train or work as hard as I once did” Justine Henin-Hardenne
  • Immune senescence Time (years) Magnitude of T cell immunity
  • Does CMV infection contribute to immune senescence ?
  • Elderly individuals who are CMV seropositive die 4.5 years earlier than uninfected individuals
  • CMV-specific immunity in immunosuppressed patients
  • CMV was a major cause of death in the early days of stem cells transplantation CMV pneumonitis
  • Patients have very few CMV-specific T cells in the first three months following SCT Time post-SCT Number of CMV-specific T cells
  • Is it possible to transfer T cells into the patient to correct the early period of immunodeficiency ? CMV-specific T cells
  • BMT is the ideal setting for adoptive transfer of T cells D D P P Time Following SCT, the patient is immunologically tolerant of cells taken from the donor
  • Use tetramers to bind to CMV-specific T cells in the donor Stain T cells FACS analysis T Cell PE
  • T cells that bind tetramer can be selected with magnetic beads T Cell PE
  • Transferred T cells can expand and clear CMV viraemia ( Cobbold et al, JEM 2005) 2.10 6 CMV-specific T cells were given 99.5% Pre-infusion blood sample 0% •  Prior to infusion the patient had CMV viraemia •  No CMV-specific T cells were present 0.5% 9 days later T cells were present and the patient became CMV negative Blood sample 9 days after infusion
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  • What can we do to control CMV?
    • Anti-viral medication
      • Will this reduce the CMV-specific immune response ?
      • Starting trial of anti-viral drugs in elderly donors
    • Vaccination
      • Can we eradicate CMV ?
  • Do we want to eradicate CMV ?
  • Could CMV have beneficial effects ?
    • Allergy
    • Auto-immunity
    • Boost immunity to others pathogen
  • What is homo sapiens ? + + + 10 14 cells 10 15 cells a lot..
  • Conclusions - Cytomegalovirus
    • CMV is the most immunodominant pathogen for the human immune system
    • Clinical features are subtle but potentially profound in immune competent donors
      • These may potentially be modulated by anti-viral drugs
    • Reactivation is a major concern in immune suppressed donors
      • We are tackling this with cell therapy
    • There are likely to be advantages for us in having CMV infection
      • We need to use epidemiology to find our what these are
  • The immune response to cancer
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  • Cancer Testis Antigens (CTAgs)
    • Proteins expressed by germline cells but not other normal tissues
    • There is a tesis-blood barrier so immune tolerance is not established against CTAgs
  • MAGE-1 immunohistochemistry stain of human testis – Old LJ (2003)
  • testis ovary trophoblast Bladder cancer
  • Cancer-testis Antigens (CTAgs) in cancer
    • • Also expressed in many cancers
    • • May reflect the acquisition of a ‘germline-transcription profile’
    • • This could be advantageous for survival, proliferation and invasion
    • This can lead to a cellular immune response that may be valuable against the tumour
  • Tumour regression following vaccination MAGE antigens in a melanoma patient Evolution of skin metastases on the leg of patient EB81 during treatment. van Baren N et al 2005 (A) (B) (C) (A) Before vaccination (B) After four vaccinations with ALVAC (after 3 months) (C) After 10 months
  • MAGE proteins are expressed in myeloma
    • Van Baren 1999
    • T cells purified from myeloma patients at different stages of disease
    • cancer-testis antigen peptides used to screen f o r tumour - specific T-cells using the cytokine secretion assay
    Study of the CD8+ T cell response to CTAg in Multiple Myeloma
  • PBMCs only PBMCs + RVRF PRE POST 0.05% 0.01% 0.00008 0.004 Example of CTAg-specific cell responses in myeloma CD8 IFN 
    • 15 out of 37 myeloma patients showed a CTAg-specific T cell response which measured between 0.01 and 0.7% of the CD8+ T cell pool
    CTAg-specific CD8+ T cell immunity in myeloma patients Goodyear et al 2005, 2008
  • Technical issues
    • Used the cytokine secretion assay
    • Immune responses very difficult to detect with HLA-peptide multimers
      • Low frequency T cell response
      • Low affinity T cell binding
  • Question concerning this T cell response
    • Does it have any effective activity against the tumour
    • Is it just a useless immune response to proteins present within the tumour
    • How do the immune responses correlate with the clinical progression of the disease
  • The CD8 response actually increases in the terminal stages of disease
  • MAGE – specific CD8 T cell clones can kill tumour when they are cloned in vitro (iii) (ii)
  • What about CD4 cells ?
  • Multiple myeloma has a pre-malignant phase
    • Monoclonal gammopathy of uncertain significance (MGUS)
      • a small monoclonal paraprotein
      • no clinical damage
      • 1% risk per year of developing myeloma
  • Strong CD4+ responses can been seen in MGUS Pre-sort Post-sort DMSO MAGE-A3 149-160 MAGE-A3 243-258 MAGE-A3 281-295 MAGE-A1/A3 121-134 / MAGE-A3 191-205 SEB
  • CD4 and CD8 responses show a different pattern in MGUS and myeloma Multiple Myeloma MGUS Positive Negative Positive Negative CD4 1 29 4 26 CD8 13 42 1 weak 20
  • Does CD4+ T cell immunity play a role in controlling the progression of MGUS ?
    • T H 1 CD4+ T cell responses determine clearance or progression of papilloma-virus infections
    • Indicates role for vaccination to boost CD4+ immune responses
  • CD4 CD8
  • CD4 immunity may determine the efficacy of the immune response CD4
  • The balance of inflammatory and regulatory CD4 immunity may be critical Th1 - IFN  Treg - suppression CD4 CD4
  • Th1 - IFN  Treg - suppression CD4 CD4
  • Th1 - IFN  Treg - suppression CD4 CD4
  • Pattern of CTAg immunity
    • Can they really protect against disease ?
    • Do healthy donors have subclinical tumour cells ?
    • Can tumour cells remain latent for years ?
  • 2000- renal transplant patient developed melanoma in kidney and breast 2000 - another transplant patient 2 developed melanoma in kidney - Registry showed both patients had been transplanted from same patient in 1998 - This patient had received excision of 2.6mm melanoma in 1982 Tumour latency Mackie 2003
  • Challenges
    • Relatively low frequency response
    • Efficacy unclear
    • Potential role for vaccination or adoptive transfer
  • Conclusions
    • Cancer testis antigens may represent an important target for tumour-specific immune responses
    • CTAg-specific CD8+ T cells are detectable in patients after stem cell transplantation
    • CTAg expression can be upregulated by demethylation treatment in tumour cell lines
  • Acknowledgements
    • Naeem Khan
    • Mark Cobbold
    • Batoul Pourghysari
    • Charles Craddock
    • Oliver Goodyear
    • Guy Pratt
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