Lecture 16: Adaptive Immune Response & Bioassays - PDF

Week 1 Tue 10th Sept Lecture Module Introduction Week 2 Mon 16th Sept Lecture 1 Use of mammalian cells Tue 17th Sept Lecture 2 Cell Culture Laboratory Lab layout, Equipment and Materials Week 3 Mon 23rd Sept Lecture 3 Contamination control...

Week 1 Tue 10th Sept Lecture Module Introduction Week 2 Mon 16th Sept Lecture 1 Use of mammalian cells Tue 17th Sept Lecture 2 Cell Culture Laboratory Lab layout, Equipment and Materials Week 3 Mon 23rd Sept Lecture 3 Contamination control Tue 24th Sept Lecture 4 Contamination control Week 4 Mon 30th Sept Lecture 5 Contamination control Tue 01st Oct Lecture 2, 3, 4 and 5 recap and sample assessment questions Week 5 Mon 07th Oct Lecture 6 Nutrient uptake Tue 08th Oct Lecture 7 Nutrient uptake and sample assessment questions Week 6 Mon 14th Oct Lecture 8 Biology of Culture Cells Tue 15th Oct Lecture 9 Cell culture media Week 7 Mon 21st Oct Lecture 10 Cell culture media postponed Tue 22nd Oct Lab 3 data analysis Reading Week Week 8 Mon 04thNov Lecture 10 Cell culture media Tue 05 Nov th Lecture 11 Cell Culture Media Week 9 Mon 11th Nov Lecture 12 Growing mammalian cells Tue 12th Nov Lecture 8, 9, 10 and 11 recap and sample assessment questions Week 10 Mon 18th Nov Lecture 13 Monitoring growth Tue 19th Nov Lecture 14 Cryopreservation of cells and Lecture 12, 13 and 14 recap and sample assessment questions Week 11 Mon 25th Nov Lecture 15 Innate immune response Tue 26th Nov Lecture 16 Adaptive immune response & Bioassays Lecture 15 and 16 recap and sample assessment questions Week 12 Mon 02nd Dec Revision Tue 03rd Dec  Overview of the Immune System Lecture Overview Introduction: Why discuss this topic Main discussion: Adaptive Immune System Conclusion: Take home message BIOT6012 Mammalian Biotechnology Lecture 16 Slide 2  Overview of the Immune System Introduction Having considered innate immunity in lecture 15, the goal now is: to define adaptive immunity to identify the forms and properties of adaptive immunity to describe the difference between cell-mediated immunity (T-cells) and antibody-mediated humoral immunity (B-cells). Immune System Innate Adaptive (Nonspecific) (Specific) 1o line of defence 2o line of defence Interactions between the two systems BIOT6012 Mammalian Biotechnology Lecture 16 Slide 3  Overview of the Immune System Adaptive Immunity – Key Features Not present at birth Specific Develops only after exposure to a specific antigen Can be active (naturally acquired or artificially induced) or passive (naturally acquired or artificially induced) Immunological memory BIOT6012 Mammalian Biotechnology Lecture 16 Slide 4  Overview of the Immune System Adaptive Immunity ACTIVE IMMUNITY – You develop PASSIVE IMMUNITY – using your own antibodies, develops after antibodies produced elsewhere. Natural exposure to an antigen. Can be (e.g. mother to baby) or artificial (e.g. natural (e.g. a virus) or artificial monoclonal antibodies as therapies) (e.g. vaccination) BIOT6012 Mammalian Biotechnology Lecture 16 Slide 5  Overview of the Immune System Humoral and Cellular Adaptive immunity Humoral immunity Cellular immunity Adaptive immunity involves the coordinated activities of two major classes of cells to provide specific defences. B-cells T-cells BIOT6012 Mammalian Biotechnology Lecture 16 Slide 6  Overview of the Immune System The T cell response (cellular immunity) Types of T-cells CD4+ Helper Cells – help in the maturation of B cells into plasma cells and memory B cells – help enhance activate cytotoxic T cells CD8+ Cytotoxic Cells – cause lysis of virus-infected and tumour cells. Memory T Cells – Once they come into contact with an antigen naive T cells differentiate into effector cells (CD4+ and CD8+ cells) and memory T cells. Memory T cells are long-lived and can quickly expand to large numbers of effector T cells upon re- exposure to the antigen. – provide the immune system with “memory” against previously encountered pathogens. Natural Killer T Cells (not to be confused with NK cells from the innate response) – Whilst most T cells function based on recognition of MHC class molecules, natural killer T cells are able to recognise other antigen classes. Once activated they are also able to perform the same functions as CD4+ and CD8+ cells. BIOT6012 Mammalian Biotechnology Lecture 16 Slide 7  Overview of the Immune System The T cell response (cellular immunity) T-cells must be activated by exposure to an antigen. T-cells are activated by antigens bound to specific receptors in the plasma receptors of other cells. This process is called antigen presentation (remember neutrophils, macrophages and dendritic cells in innate immune response, lecture 15 slide 12). There are two types of receptors that bind antigens. These are called major histocompatibility complex (MHC) proteins. There are two types of these; MHC Class-I: present in all nucleated cells. Present antigen to cytotoxic T-cells. MHC Class-II: present on specialised antigen-presenting cells (including macrophages, dendritic cells and B-cells). Binds with helper T cells. BIOT6012 Mammalian Biotechnology Lecture 16 Slide 8  Overview of the Immune System The stages of a Cytotoxic T-Cell response MHC-I 1. Antigen recognition + antigen → Cytotoxic T cells recognise an antigen bound to MHC-I receptor on another cell. 2. Activation & Division → Antigen recognition leads to T-cell activation and cell division producing active cytotoxic T-cells and memory T-cells. 3. Destruction of target cell → The active cytotoxic T-cells destroy the antigen bearing cells in a number of ways; → Perforin release → Cytokine release → Lymphotoxin release BIOT6012 Mammalian Biotechnology Lecture 16 Slide 9  Overview of the Immune System The B cell response (antibody-mediated immunity) B cells produce specific antibodies that target specific antigens Sensitization: Antigen in the blood binds to antibodies (same structure) attached to outside of B-cell. B-cell engulfs the antigen and then put it on to MHC-II proteins on its membrane. B-cell is now on stand-by (sensitized) but does not become active until its get the ‘ok’ from helper T-Cells. BIOT6012 Mammalian Biotechnology Lecture 16 Slide 10  Overview of the Immune System The B cell response (antibody-mediated immunity) B cells produce specific antibodies that target specific antigens Activation: The T cell attaches to the antigen-MHCII complex and stimulates the release of cytokines. These cytokines stimulate further B-cell differentiation. BIOT6012 Mammalian Biotechnology Lecture 16 Slide 11  Overview of the Immune System The B cell response (antibody-mediated immunity) B cells produce specific antibodies that target specific antigens Division and Differentiation: The activated B-cells divide and then differentiate into two cells types; Plasma cells → these synthesise and secrete large amounts of antibodies that recognise the antigen. Memory B cells → these ‘remember’ the antigen and can produce plasma much quicker if the antigen ever comes back BIOT6012 Mammalian Biotechnology Lecture 16 Slide 12  Overview of the Immune System Basic structure of an antibody Antibody molecules are Y-shaped that are made up of two parallel polypeptide chains; - One pair of short light chains - One pair of heavy long chains Antibodies also have a constant segment and a variable segment. There are only five types of constant segments, and this is how antibodies are classified; (IgG, IgM, IgA, IgE and IgD). The variable region is the antigen Note: another name for an binding site of the antibody. antibody is an immunoglobulin (Ig) → this is normally used when describing types (eg IgG). BIOT6012 Mammalian Biotechnology Lecture 16 Slide 13  Overview of the Immune System Classes of Antibodies Class Function Remarks IgG Responsible for defence against Largest class. 80% of all antibodies many viruses, bacteria and bacterial are IgG. toxins. IgM Responsibility for the incompatibility First antibody type produced between different blood types. Other following initial antigen exposure. forms attack bacteria insensitive to Production decreases and IgG IgG production rises. IgA Attacks pathogens before they enter Found in glandular secretions the body tissues (mucus, tears and saliva) IgE Accelerate inflammation after Stimulates the release of histamine exposure to antigen. and other inflammatory chemicals from mast cells. IgD Binds antigens in the extracellular This binding plays a role in B Cell fluid to B cells sensitization. BIOT6012 Mammalian Biotechnology Lecture 16 Slide 14  Overview of the Immune System Antibody function (How do antibodies work?) methods used to eliminate threats 1. Neutralisation Antibodies can bind viruses or bacterial toxins, making them incapable of attached to a cell. 2. Agglutination: Antibodies manage to ‘clump’ infectious agents together which promotes phagocytosis. 3. Activation of Complement: Part of the antibody constant segment can bind complement. This activates the complement system and destroys the antigen 4. Antibody Dependent Cell Mediated Toxicity (ADCC): When an antigen is covered with antibodies, this attract phagocytes. These engulf the pathogens, and destroy cells with foreign or abnormal plasma membranes. 5. Opsonization: Antibodies bound to antigens make pathogens with a slick plasma membrane easier to phagocytose. 6. Stimulate inflammation: - When an antigen is covered with antibodies, this attract phagocytes. These engulf the pathogens, and destroy cells with foreign or abnormal plasma membranes. BIOT6012 Mammalian Biotechnology Lecture 16 Slide 15  Overview of the Immune System 1. Neutralisation 2. Agglutination 3. Activation of complement 4. ADCC 5. Opsonization 6. Inflammation BIOT6012 Mammalian Biotechnology Lecture 16 Slide 16  Overview of the Immune System Primary and Secondary response to antigen exposure – immunological Memory Primary: Initial exposure to antigen Secondary: on repeated exposure IgM antibodies produced first followed by IgG On a second exposure memory B cells differentiate into plasma cells right away so the response is much faster. → memory cells can survive for >20 years. → this is the reason why immunization is effective. The primary response takes about two weeks to develop peak antibody levels, and antibody concentrations do not remain elevated. In the secondary antibody response, antibody concentrations increase very rapidly to much higher levels and remain elevated for a much longer period. BIOT6012 Mammalian Biotechnology Lecture 16 Slide 17  Overview of the Immune System Conclusion Adaptive immune response develops only after exposure to a specific antigen and the response is specific Cellular Adaptive immunity – T-cells Humoral Adaptive immunity – B-cells Immunological memory: memory cells are long-lived and can quickly expand to large numbers re-exposure to the antigen Remember: intricate relationship between the components of the adaptive immune response and also between the innate and adaptive immune responses. BIOT6012 Mammalian Biotechnology Lecture 16 Slide 18