Specific Acquired Immunity - Diebel Flashcards
What molecules are displayed by MHC Class I?
- Antigens synthesized within the cell
- samples intracellular proteins to display on surface
What molecules are displayed by MHC Class II?
- Antigen that are products of phagocytosis
- whole bodies produced outside the cell
Which cell types express MHC Class I?
- All cells except RBCs
- reason for persistence of malaria
Which cell types express MHC Class II?
- Monocytes/Macrophages
- Dendritic cells
- B-cells
- Epithelial cells of the thymus
Which T-cell type interacts with MHC Class I?
CD8+ killer T-cells
Which T-cell type interacts with MHC Class II?
CD4+ helper T- cells
What is the result of T-cell interaction with MHC Class I?
- Naive CD8+ T-cell induces:
- Memory CD8+
- Effector CD8+
What is the result of T-cell interaction with MHC Class II?
- Naive CD4+ helper T-cell induces:
- Memory CD4+ T-cell (may begin before MHC interaction?)
- TH1
- TH2
- TH17
- TFH
- Treg
What cytokines help a hematopoietic stem cell differentiate into a Lymphoid Progenitor cell?
IL-3 & IL-7
What are common lymphocyte markers of T-cells?
- CD3 - makes up the signaling chains of the TCR and plays an essential role in cell surface expression of the TCR and TCR signal transduction.
- CD4 - Coreceptor for activation of MHC class II–restricted T cells. Thymic differentiation marker for T cells and receptor for HIV.
- CD8 - Coreceptor for the activation of MHC class I–restricted T cells. Thymic differentiation marker for T cells
- CD23 - subset
What are common lymphocyte markers of B-cells?
- CD1 - Antigen-presenting proteins that bind lipid and glycolipid antigens and presents them to T-cell receptors on natural-killer T cells.
- CD19
- CD20
- CD23
- CD40 - molecule that interacts with TFH to get activated and class switch
- CD79a - part of the BCR complex
- CD79b - part of the BCR complex
What are the five specialized subtypes of T helper cells?
- TH1
- TH2
- TH17
- TFH
- Treg
(All have CD4 molecular marker)
What role do Type 1 Helper T-cells play within the immune system?
- recognize antigen
- make a lymphokine that attracts macrophages to area where antigen has been recognized
- intense inflammation
What role do Type 2 Helper T-cells play within the immune system?
- stimulate macrophages to become alternatively activated
- promote healing = M2 macrophage
- able to function in walling-off pathogens
- important in parasite immunity
What role do Type 17 Helper T-cells play within the immune system?
- main role = focused inflammation
- more powerful than TH1
- implicated in many serious forms of autoimmunity
What role do Follicular Helper T-cells play within the immune system?
- stimulated by antigen
- migrate from T-cell areas of lymph nodes into the B-cell follicles
- help B-cells get activated
- make IgM, IgG, IgE, and IgA antibody subclasses
- provide info for class switching
What role do Regulatory T-cells play within the immune system?
- make cytokines that suppress the activation and function of TH1, TH2, and TH17
- keep immune response in check
- use IL-10 to deactivate macrophages
What is wrong with Treg T-cells in IPEX (immunodysregulation polyendocrinopathy enteropathy X-linked syndrome)?
- Failure of peripheral tolerance due to defective regulatory T-cells
- Treg doesn’t function → cannot turn off inflammation
(due to dysfunctional transcription factor)
What role do Cytotoxic/Killer T-cells play within the immune system?
- destroy any body cell they identify as bearing a foreign or abnormal antigen on its surface
What are the main cytokines that drive general activation of T-cells activation and differentiation?
IL-2 & IL-15
What are the main cytokines that drive T helper cells to TH1 helper cell subtypes?
IL-12 & IFN-gamma (IFN-γ)
What are the main cytokines that drive T helper cells to TH2 helper cell subtypes?
IL-4
What is the general mode of action that killer T cells use to kill target cells?
- Kill by FAS - FAS ligand interaction
- T-cells expressing the FAS ligand bind to FAS, a protein on a target cell to induce caspase activation and apoptosis.
- Kill by secreting toxic agents as well
- TNF (a cytokine) induces apoptosis
- Perforin is a pore-forming protein
- Granzymes also induce apoptosis
How are target cells recognized by killer T-cells?
- look for antigen fragments on MHC Class I antigen-presenting molecules
- on ALL cells except for red blood cells
