Immunology (Subject) / Adaptive IS and Tolerance (Lesson)

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Course 10 HAN Immunology

This lesson was created by FriediFehlau.

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  • t-cell tolerance - in the thymus - positive and negative selection
  • b-cell tolerance - in the bone marrow - only negative selection
  • role of regulatory t-cells (treg) - secrete immunosuppressive cytokines: IL-10, TGFβ - consume IL-2 -> less -cells - cytolysis of t-cells - block dendritic cells
  • MHC1 presents only intracellular antigens on all cells
  • MHC 2 also extracellular antigens only Antigen presenting cells (APC)
  • where are T-cells activated? paracortex of lymphnodes (t-cell area)
  • what happens in the t-cell area? Explain t-cell activation: DC meets a naive t-cells,  three Signals: 1. MHC-peptide binds t-cell receptor 2. co-stimulation (CD80/CD86 - CD28) 3. Cytokines
  • naive t-cell + IL12 becomes Th1 secretes IFNγ, TNFα, IL2
  • role of Th1 helps forming cytotoxic t-cells (CTLs) helps activate macrophages
  • naive t-cell + IL-4 becomes Th2 secretes IL-4, IL-5, IL-13
  • role of Th2 helps b-cells
  • naice t-cell + TGFß or IL-10 becomes Treg secretes TGFβ and IL-10
  • naive T-cell + TGFß and Il-6 becomes Th17 secretes IL-17
  • fundamental roles of Antibodies Neutralization Opsonization complement activation
  • difference between affinity and avidity affinity is the binding strength of a single receptor avidity is the overall strength, the sum of the affinity  
  • how is an activated b-cell called? plasma cell
  • what is meant by a t-independent response? the antigen is not a protein, thus t-cell can not bind to it only b-cells can recognize lipids or sugars (but no memory cells ar formed)
  • t-cell tolerance mechansism central tolerance: in thymus, negative selection: deletion of  t-cells with high affinity to self-antigens, positive selection: t-cell selection by IL-x and MHC recognition peripheral tolerance: outside the thymus, regulation of mature self-reactive t-cells
  • tolerogenic dendritic cells induce Tregs when there are no danger or inflammatory signals
  • how do self-antigens get to the thymus? mTECs (medullary thymic epithelial cells) express tissue-restricted antigens due to AIRE (autoimmune regulator)
  • B-cell tolerance mechanism 4 different fates: Central: 1) self-reactive -> clonal deletion -> apoptosis 2) wrong receptor -> receptor editing -> different receptor peripheral 3) intrinsic: lack of co-stimulation 4) extrinsic: lack of help
  • B-cell activation in the periphery by Th2 or dendritic cells three signals: 1) MHC2 (TH2) or MHC1 + antigen 2) co-stimulation 3) cytokines: IL-4, IL-5
  • Alternative splicing Primary RNA transcript is spliced, Exon coding membrane-bound proteins gets spliced IgM is secreted, B-cell become plasma cell
  • Isotype switching subclass of heavy chain changes -Y receptor function of AB changes
  • somatic hypermutation repeated random mutations in the variable region of heavy and light chains -> variability
  • features of innate immunity physical bariers chemical barriers NK cell, macrophages, neutrophils inflammation
  • features of adaptive immunity latency (5-6) antigen specificity diversity immunological memory non/self-recognition

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