Lecture 17: Transplant Immunology Flashcards Preview

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Flashcards in Lecture 17: Transplant Immunology Deck (30):
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Autografts

grafts exchanged from one part of the same individual

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Isografts

grafts exchanged between different individuals of identical genetic constitutions (e.g. idential twins) 

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Allografts (allogeneic) 

  • Grafts exchanged between nonidentical members of the same species

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Xenografts (xenogeneic) 

  • graft exchanged between members of different species 
    • are particularly susceptible to rapid attack by naturally occuring Abs and complement
    • The insertion of human genes into the genomes of the donor animals (miniature swine) increases the chances of successful survival 

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Classs _______  HLA Ags  are particularly storng barriers to transplantation 

Class-I (HLA-A and HLA-B) 

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What are the three most important Class II HLA pairs  for transplation 

  • HLA-DR
  • HLA-DP
  • HLA-DQ

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There are hundreds of allelic forms of HLA molecules but each individual only inherits 

10-12 alleles/person 

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Are HLA Ags expressed co-dominantly 

yes 

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Types of Rejections 

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Mechanisms of Rejections 

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Can Chronic rejections be inhibited by immunosuppressive therapy 

No

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Direct vs Indirect Allorecognition 

  • The direct pathway is primary response against graft: 
    • The T cell receptors on recipient T cells directly recognize the donor MHC molecules 
  • The indirect response: 
    • The recipient T cells recognize donor MHC molecules that have been processed by recipient APCs
    • The donor MHC molecules are presented as peptides in the context of recipient MHC class II molecules 
    • The indirect pathway is important during chronic rejection (when the number of donor professional APCs is low to simulate a direct immune response) 

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NK cells may be recruited at two points at least during the virus infection. They exhibit an innate (early in the course of infection) antiviral role following activation by epithelium derived ____. At a later stage of infections, NK cells are activated by 

  • IFN-alpha (early)
  • Cytokines IFN-gamma and IL-2 produced by Th1 cells specific for the virus (Late) 

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After resolution of the infection, virus-specific memory T and B cells reside long term in 

lymph nodes, spleen, and bone marrow 

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Innate immunity to intracellular bacteria

  • is mediated by phagocytes and NK cells interactions among which are mediated by IL-12 (DCs and Macrophages) and IFN-gamma (NK cells). May control bacterial growth, but elimination of the bacteria requires adaptive immunity 

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Adaptive immunity for intracellular bacteria infection

  • adaptive immunity is cell-mediated immunity (CTLs) in which Th1 cell-produced IFN-gamma activates phagocytes to eliminate the microbes 

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Activated DCs and Macrophages produce ___ and ___ which activate NK cells 

IL-12, IL-15

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Fungi infections are recognized by _____ binding the PAMPs

  • PRRs (TLRs and C lectin-like receptors)
  • (note the detection of beta-glucan by dectin 1 is also important)

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What helper cells are the most important for fungal infections

Th1

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What is the major receptor involved in the non0psonic recognition of fungi

Mannose receptor (MR)

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____ is a specific receptor for beta-glucans expressed on macrophages

Dectin-1

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_____ are polysaccharide PAMPs that contain only glucose as structural components

beta-glucans 

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DECTIN-1 binds and internalizes beta-glucans and mediates the production of reactive oxygen species (ROS), activation of _____ and subsequent secretion of proinflammatory cytokines

NF-kB

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