Basic Immunology Lecture 4 PDF

# Basic Immunology (Lecture -4) ## Innate & Adaptive Immunity ### Immunology and Microbiology Unit **Innate and adaptive immunity:** - **Innate (Natural) Immunity:** Any inborn resistance that is present the first time a pathogen is encountered: it does not require prior exposure and is not modifi...

# Basic Immunology (Lecture -4) ## Innate & Adaptive Immunity ### Immunology and Microbiology Unit **Innate and adaptive immunity:** - **Innate (Natural) Immunity:** Any inborn resistance that is present the first time a pathogen is encountered: it does not require prior exposure and is not modified significantly by repeated exposure to the pathogen over the life of individual. - **Acquired Immunity:** A resistance that is weak or absent at the first exposure, but increases dramatically with subsequent exposures to the same specific pathogen. ## Components of Innate Immunity: 1. **Barriers to infection** 2. **Innate Cellular response** which depends on: - **Innate phagocytic cellular activity:** - Antigen presenting cells: Monocytes, Macrophages, which stimulates T-helper cell response - Killer cells: neutrophils and Eosinophils - **Phagocytosis activated by innate soluble proteins** 3. **Innate Soluble mediators:** - **Cytokines of innate:** IL-1, IL-12 and INF-α and β. - **Acute phase proteins (humoral response)**. - **Complement C3b: alternative pathways** 4. **The Inflammation process** ## Innate Soluble mediators: - **Plasma Proteins:** - A variety of plasma proteins like pattern recognition receptors and acute phase protein that interact with microbial target non-specifically and activates phagocytosis. | Soluble Plasma Proteins | Major microbial targets | Effects | |---|---|---| | C-reactive protein (CRP) _Pattern recognition receptor_ | Polysaccharides of microbes | Opsonization. | | Mannose binding proteins _Pattern recognition receptor_ | High Mann glycoprotein | Opsonization and complement activation | | Soluble CD14 _PRR_ | Lipopolysaccharide (LPS) of many bacteria. | Opsonization. | | Complement C3b | Polysaccharide of bacteria | - Opsonization. - Alternative complement activation. | ## Opsonization and Phagocytosis: - A diagram depicting Opsonization and Phagocytosis in which a Microbe is surrounded by a host cell and a soluble PRR (e.g. Complement) - PRR's on the host cell bind pathogens in order for the Microbe to activate phagocytosis - PAMPs are pathogen-associated molecular patterns ## Opsonization and Phagocytosis: - A diagram which represents opsonization and phagocytosis. - A bacterium with complement attached to its surface binds to a complement receptor on a phagocytic cell. - Binding causes phagocytosis of the bacteria. ## Cellular activity of Innate response: 1. **Activated antigen presenting cells stimulate T-helper Lymphocytes:** - **In bloodstream** APC: The Monocytes - **In body organs and Lymph nodes:** The Macrophages and DC cells. 2. **Killing of infectious agents:** - **Neutrophils:** Bacterial killing - **Eosinophils:** Parasites killing. 3. **Mechanism of inflammation** **Reading: ( Chapter 5): from page 48 (Cytokines) to page 51.** ## Components of Adaptive Immunity: 1. **Adaptive immune cells:** - **Memory T-helper cells activity** - **Memory T-cytotoxic cell activity** - **Memory B-Lymphocyte activity** 2. **Adaptive soluble mediators:** - **Cytokines produced by T-helper and B-cells** - **Complement components of the classical pathway** 3. **Soluble and cell-bounded proteins:** - The Antibodies (immunoglobulins) ## Cytokines: - Low-molecular weight soluble proteins produced by immune and non-immune (somatic) cells, act as signaling molecules between cells (called interleukins) - Cytokines produced by Lymphocytes are known as Lymphokines. - Cytokines that can attract cells to the site of inflammation 'chemotaxis' are known as chemokines. - Cytokines that "interfere" with viral replication by protecting cells from virus infections are known as interferons - **Cytokines include:** Interleukins, Interferons, Lymphokines, and Chemokines. ## Functions of Interleukins: 1. **Cellular interaction:** inflammatory response due to innate and adaptive immunity 2. **Cellular growth and differentiation** ## Functions of Interferons: - Interferons are rapidly produced by the virally infected cells to protect the neighboring cells. - Interferons activate phagocytosis and apoptosis of infected cells. 1. **Anti-viral infection** 2. **Fight Tumors** ## Cytokines of Innate Immunity: - **Interleukins (IL):** IL-1, IL-6, IL-12, and TNFα - **Interferons (IFN): Type I interferons** - IFN- α produced by dendritic cells - IFN- β Produced by fibroblasts. ## Cytokines of Adaptive Immunity: - **Interleukins (IL):** IL-2, IL-4, IL-5, IL-10, IL-13. - **Interferones (IFN): Type-2 IFN:** - INF-γ ## Functions of Cytokines: | Cytokine | Cellular Source | Targets | Function | |---|---|---|---| | IL-1 | - Macrophage, - B cell | T cell, B cell, End | - Leukocyte activation - End. Adhesion | | IL-2 | TH-1 (CD4 cell) | T cell (helper and T cytotoxic), NK cell, and B cell | T cell proliferation. | | IL-4, IL-5 | - TH-2 (CD4 cell) | B cell, T cell, Eos | Differentiation of TH-2 and B cell | | IL-8 | - Macrophages - others | PMN, Bas, Lymphocytes | Chemoattractant | | IL-10, IL-13 | - TH-2, - CD8 cells | B cell, TH-2, Mac. | Inhibits IL-2, INFγ. Down reg. IL-12 | | TNF-α | Mac, PMN, Т, В cells. | Mac, PMN, T, Endothelial cells. | Inflammatory Mediator. | ## Cytokines and Immune Cells Interaction: - Diagram depicting a Dendritic cell interacting with a naive T cell. - The dendritic cell is connected to the naive T cell by CD28. - The dendritic cell has MHC-II and CD80/86. - The Naive T cell has a TCR - The dendritic cell is connected to a pathogen which is connected to an Endocytic PRR by Toll ## Functions of Interferons: | Interferons | Cellular Source | Targets | Function | |---|---|---|---| | INF-α | Lymphocytes, Epithelium, fibroblasts. | Wide variety of cells. | - Up-regulates MHC class I. - Inhibit viral proliferation | | INF-β | Epithelium, fibroblasts. | Wide variety of cells. | - Up-regulates MHC class I. - Inhibit viral proliferation | | INF-γ | CD8, CD4, and NK cells. | T, B, M, NK, End. | - Anti-Viral. - Anti-Parasitic. - Enhances MHC Class I and II expression. | ## Thank you!