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USMLE
Real Immuno 2
Question | Answer |
---|---|
T-cell differentiation: Where do T-cell precursors come from and where do they go? | From the bone marrow to the thymus |
What CD marker is evidence of T-cell differentiation? Which T cell types carry it? | CD3 Cytotoxic T-cell & Helper T-cell |
T-cell differentiation: What happens to T-cell precursors when they enter the thymus, and what are they called? | Once T-cell precursors acquire and display CD4 and CD8, they are cortical thymocytes. |
T-cell differentiation: What is expressed by the T-cell in its development when it undergoes positive selection? | Both. CD4 positive and CD8 positive |
T-cell differentiation: Where in the thymus are cells which are positive for both CD4 and CD8 located? | Thymic cortex |
T-cell differentiation: What is expressed the T-cell in its development when it undergoes negative selection? | Either CD4 positive or CD8 positive, NOT BOTH |
T-cell differentiation: Where in the thymus are cells which are positive for either CD4 or CD8 located? | Thymic medulla |
T-cell differentiation: What are the two types of helper T cells and where do they differentiate? | In the lymph node, helper T cells differentiate into Th1 cells, and Th2 cells. |
Differences between Th1 and Th2 cells: Stimulant for differentiation from archetypical helper T cell. | Th1: IL-12 from both other Th1 cells and antigen-presenting dendritic cells Th2: IL-4 from other Th2 cells and presumably an unknown factor from dendritic cells |
Differences between Th1 and Th2 cells: Cytokines produced by both types | Both: IL-2 Th1: IFN-gamma, TNF-beta Th2: IL-4, IL-5, IL-6, IL-10, IL-13 |
Cytokine effects: Interleukin 2 | Stimulates T-cell growth and proliferation |
Cytokine effects: Interferon gamma | Secreted by Th1 cells 1. Inhibits Th2 cytokines 2. Induces class I and II MHC 3. Stimulates differentiation of monocytes into macrophages. 4. Activates macrophages. |
Cytokine effects: Tumor Necrosis Factor alpha | Secreted by Mphages. 1.Incr IL-2 receptor synth by Th cells 2.Attracts & activates Neutrophils 3.Incr B-cell prolif 4.Stim dendritic cell migration to nodes 5.sepsis, cachexia, fever, acute phase proteins |
Cytokine effects: Interleukin 4 | 1. Growth of B-cells 2. Growth and proliferation of T-cells 3. Synthesis of IgE 4. Class switching of IgG to IgE 5. Inhibits IL-8, IL-1, and TNF-alpha |
Cytokine effects: Interleukin 5 | 1. Differentiation of B cells 2. Class switching of IgA 3. Production and activation of eosinophils |
What cytokines stimulate the acute phase response? | 1. IL-1 2. IL-6 3. TNF-alpha |
What are acute phase response proteins used for? | 1. Augment immune response (complement, Ig) 2. Regulate the extent of response (protease inhibitors like alpha-1-antitrypsin) 3. Stimulate additional responses (alpha-2-macroglobulin) |
Cytokine effects: Interleukin 10 | Big picture: Stimulates Th2 while inhibiting Th1 Specifically inhibits: 1. IL-8 2. IL-1 3. TNF-alpha 4. IFN-gamma |
What releases: Interleukin 10 | 1. Th2 cells 2. Macrophages |
Differences between Th1 and Th2 cells: Major effects | Both: Downregulate each other Th1: Activates all lymphocytes and APCs, especially CD8 cells and macrophages. Th2 cells: 1. B cells: Increased differentiation, proliferation, antibody, and class switching. 2: Activation of eosinophils |
What releases: Interleukin 2 | Th cells |
What releases: Tumor Necrosis Factor alpha | Macrophages (emphasized) and Th1 cells |
What releases: Interferon gamma | Th1 cells (emphasized) and NK cells |
What releases: Interleukin 5 | T cells (especially Th2) and mast cells |
What releases: Interleukin 6 | T cells (especially Th), macrophages, and endothelial cells |
What is MHC and what codes for it? | Major Histocompatability Complex encoded by Human Leukocyte Antigen (HLA) |
What genes code for MHC I? | 1. HLA-A 2. HLA-B 3. HLA-C |
What genes code for MHC II? | 1. HLA-DP 2. HLA-DQ 3. HLA-DR |
MHC I and II: What cells are they expressed on? | MHC I: All nucleated cells except sperm, & adult RBCs. MHC II: Antigen Presenting Cells |
MHC I and II: Where in the cell is antigen loaded onto the MHC? | MHC I: RER of mostly intracellular peptides. (Mediates viral immunity) MHC II: in an acidified endosome. (main determinent of organ rejection) |