Fortress Body 1: Immune System Introduction PDF

09/11/23 Fortress body 1: introduction to the immune system and the threats to the body: part 1 Learning objective: de ne the cell types and molecules of the innate immune response. Learning objective: de ne the cell types of molecules of the adaptive immune response. Learning objective: understand...

09/11/23 Fortress body 1: introduction to the immune system and the threats to the body: part 1 Learning objective: de ne the cell types and molecules of the innate immune response. Learning objective: de ne the cell types of molecules of the adaptive immune response. Learning objective: understand the different functions of the innate and adaptive immune response. Learning objective: understand the concept of lymphocyte recirculation. Learning objective: understand the de nitions of immune dysfunctions: allergy, autoimmunity, immunode ciency. Immune system: the group of cells, tissues and molecules that mediate immune responses. Immune response: a reaction to microbes and other non-microbial molecules. Different functions of innate and adaptive immunity: Innate immunity ( natural ): First line of host defence against infection. Always present in health. Provides immediate protection. Adaptive immunity ( acquired or speci c ): Adapts more slowly and provides a specialised defence. Proliferation and differentiation of lymphocytes. Antigens and Epitopes: Antigens: molecules recognised by the immune system. Epitopes: part of the antigen recognised and bound to antibody, or by an receptors on T and B cells. A particular antigen can have several different epitopes or repeat epitopes. This each antigen can have several epitopes that can be recognised by the immune system. Innate immune cells: Sentinels: tissue resident. Recognise invading pathogens. Alerts the immune system. Mast cells. Dendritic cells. SAKA APC's Macrophages. Phagocytes: tissue resident or recruited from blood. Engulf and kill invading pathogens and alert the adaptive immune system. Neutrophils. Macrophages. Dendritic cells. Innate lymphoid cells: tissue resident or recruited from the blood. Kill infected or transformed cells and produce cytokines. NK cells. ILC. Cytokines: Cytokines are a family of small proteins used for communication in the immune system. Cells are stimulated to produce cytokines, which are recognised by other cells, which respond to the cytokine. Cytokines play diverse roles in the regulation of an immune response: type, magnitude and location. during an inflammatory recruit coat cells more Also so theyrepathogens phagocytosed Innate immune response: Signs of in ammation: Heat ( Calor ) Redness ( Rubor ) Swelling ( Tumor ) Pain ( Dolor ) Loss of function ( Functiolaesa ) Recognition of infection by sentinel cells: Pattern recognition receptors ( PRRs ) on sentinel cells recognise: Pathogen associated molecular patterns ( PAMPs ). Comment to groups of bacteria, fungi, or viruses, but are not commonly found in host cells. Damage associated molecular patterns ( DAMPs ). Molecules released from dying cells or damaged connective tissue. Individual cells express of variety of PRR and recognise a wide range of PAMPs/DAMPs. Phagocytosis and destruction of invading pathogens: Phagocytosis is the engul ng of microorganisms or other cells and foreign particles by phagocytes. ( same as A-level ). Good clips: https://www.youtube.com/watch?v=438EovW4tzs https://www.youtube.com/watch?v=LXno0vcW2Go Alerting the adaptive immune system: A dendritic cell is an example of an antigen presenting cell. For example, the dendritic cell recognises, ingests and degrades the pathogen. Pieces of the pathogen are displayed on the cell surface. Then the dendritic cell moves around the body to try to nd a cell that recognises the pathogenic antigens that now displays on its surface. Lymphocyte activation and recirculation: 1. DC’s in the lymph node present peptide antigen to T cells. 2. Small number of T cells recognise the peptide antigen. 3. T cells become activated and proliferate. 4. T cells support B cell activation and the production of antibodies. 1. Helper T cells release cytokines that activate other cells of the immune system e.g macrophages. 2. Cytotoxic T cells destroy infected cells and release cytokines. 3. B cells produce antibodies: antibodies bind to and neutralise pathogens, enhance phagocytosis of pathogens, activate the compliment cascade. T cells and antibodies return to the site of infection to eliminate pathogens or infected cells.