Module 6 - Adaptive Immunity PDF

Adaptive/ specific immunity Mr Bashir Sumar School of Nursing and Midwifery OBJECTIVES: Define the term antigen Describe how T cells and B cells arise and explain their roles. Define an antibody and discuss their functions. Define antibody mediated (humor...

Adaptive/ specific immunity Mr Bashir Sumar School of Nursing and Midwifery OBJECTIVES: Define the term antigen Describe how T cells and B cells arise and explain their roles. Define an antibody and discuss their functions. Define antibody mediated (humoral) and cell mediated immunity. Discuss the primary and secondary responses to an antigen Explain how active and passive immunity may be acquired, naturally and artificially Overview of the body’s defences  Characteristics of the specific defences Able to identify foreign antigens (molecules) Antibody generating Specific response to destroy the foreign microbe Has a memory Cells of the Immune Response Lymphocytes (B & T cells) primary cells of the immune system (immunocompetent cells) capable of recognizing and responding to specific antigens ability to distinguish self from non-self (foreign) proteins and generate response Antigen-presenting cells Macrophages Dendritic cells  Video The Immune Response Please take some time to view the video which shows an overview of the innate and adaptive defences of our immune response. The Video is in your Learning Module for this week. Please ensure you read the next slide before viewing the video. Regarding the video on The Immune Response………… Section 200AB Copyright Act Copyright Notice This material has been provided to you by the University of Western Sydney pursuant to Section 200AB, Copyright Act, 1968, Flexible Dealing Provision for the purpose of educational instruction. Do not make further copies or share this material by any means. This material is subject to Copyright protection.  Figure 21.8 Lymphocyte development, maturation, and activation. Humoral immunity Primary lymphoid organs Adaptive defenses (red bone marrow and thymus) Cellular immunity Secondary lymphoid organs (lymph nodes, spleen, etc.) Red bone marrow 1 Origin Both B and T lymphocytes originate in red bone marrow. Lymphocyte precursors 2 Maturation T cells migrate (in blood) to the thymus and mature there. B cells mature in the bone marrow. During maturation lymphocytes develop immunocompetence Thymus and self-tolerance. Red bone marrow 3 Seeding secondary lymphoid organs and circulation Immunocompetent but still naive lymphocytes leave the thymus and bone marrow. They “seed” the secondary lymphoid organs and circulate through blood and lymph. Antigen 4 Antigen encounter and activation Lymph node When a lymphocyte encounters an antigen, that lymphocyte can be activated. 5 Proliferation and differentiation Activated lymphocytes proliferate (multiply) and then differentiate into effector cells and memory cells. Memory cells and effector T cells circulate continuously in the blood and lymph and throughout the secondary lymphoid organs. © 2013 Pearson Education, Inc. What are B lymphocytes secrete antibodies effective against microorganisms in the extracellular fluids originate in foetal bone marrow, migrate to foetal liver and lymphoid tissues to mature activated during immune response, differentiate into plasma cells (secrete antibodies) and ‘memory cells’ make up 10 to 20% circulating lymphocytes What are T lymphocytes (T cells) Originate in bone marrow, mature in thymus Make up 60-70% of circulating lymphocytes Three subclasses: 1. Helper T cells (CD4+) secrete cytokines regulate the immune response activate other T cells & B cells 2. Cytotoxic T cells (CD8+) kill virus infected and cancer cells 3. Suppressor T cells ‘dampen down’ responses eliminate microorganisms living inside cells (intracellular) Two forms of Acquired Immunity 1. Antibody-mediated immunity (humoral) involves B lymphocytes →antibody production 2. Cell-mediated immunity destruction of pathogen or “non-self” substance by T lymphocyte Remember-trigger of both system – antigens Figure 21.11 Clonal selection of a B cell. (1 of 2) Antibody mediated orHumoral immunity Primary response Antigen (initial encounter with antigen) Antigen binding to a receptor on a specific B lymphocyte Proliferation to form a clone Activated B cells Plasma cells Memory B cell— (effector B cells) primed to respond to same antigen Secrete antibodies © 2013 Pearson Education, Inc. Figure 21.11 Clonal selection of a B cell. (2 of 2) Memory B cell— primed to respond to same antigen Secondary response Clone of cells Subsequent (can be years later) identical to attack by same antigen results in ancestral cells more rapid response Plasma cells Secreted antibody Memory molecules B cells © 2013 Pearson Education, Inc.  Figure 21.16 Major types of T cells. Cell mediated or Cellular immunity Immature lymphocyte Red bone marrow T cell T cell receptor receptor Maturation displaying CD4 CD8 displaying antigen cell cell antigen Thymus Activation Activation APC (dendritic cell) Memory APC cells (dendritic cell) CD4 CD8 CD4 cells become Lymphoid either helper T CD8 cells become tissues and cytotoxic T cells or organs regulatory T cells cells Effector cells Blood plasma © 2013 Pearson Education, Inc. Figure 21.20 Simplified summary of the primary immune response. Cellular Humoral Antigen (Ag) intruder immunity immunity Inhibits Inhibits Triggers Adaptive defenses Innate defenses Surface Internal barriers defenses Free Ags may directly activate B cell Ag-infected body cell engulfed by dendritic cell Antigen- activated B cells Present Ag to activated helper T cells Becomes Co-stimulate and release cytokines Clone and give rise to Ag-presenting cell (APC) presents self-Ag complex Activates Activates Memory B cells Naive Naive CD8 CD4 T cells T cells Activated to clone Activated to clone and give rise to Induce and give rise to Plasma cells Memory Memory co-stimulation CD4 (effector B cells) CD8 T cells T cells Secrete Cytotoxic Helper T cells T cells Cytokines stimulate Nonspecific killers (macrophages and Antibodies (Igs) Together the nonspecific killers and cytotoxic T cells mount a NK cells of innate Circulating lgs along with complement physical attack on the Ag immunity) mount a chemical attack on the Ag © 2013 Pearson Education, Inc. Specific immunity can be acquired naturally or artificially; actively or passively Active immunity (= Abs made) is acquired during an infection (naturally) or vaccination (artificially). provides immunological memory (memory lymphocytes) Passive immunity (= Abs given) is acquired from the mother through placenta or colostrum (naturally) or a donor animal or human (artificially). is short lived (no memory) Immunisation the process of inducing immunity artificially exposure of a person to material (a vaccine) that is antigenic but not pathogenic Types of vaccines: killed, whole bacterial cells or inactivated viruses live, attenuated bacteria or viruses inactivated bacterial toxins parts of bacterial cells or viruses Vaccination types from Lee & Bishop (2013), p. 213 Overview – body defences front line (non-specific) defences fail …….. antigen (Ag) invades the inflammatory response tries to prevent it getting in and multiplying. if this fails the B-cell humoral response mounts an attack to inactivate the antigen over 4-5 days this leaves a legacy of antibodies and memory cells for future invasion. the T- cells meanwhile assist the B- cells in the humoral response and mount the cell mediated response if the pathogen has already invaded the tissue cells. Review of defences against diseases Non specific - 1st & 2nd line of defence Specific - 3rd line of defence -B lymphocyte: -memory cells -plasma cells-antibodies -T lymphocyte: -helper T cells -cytotoxic T cells-elimination -memory cells All lines of defences fail → disease