Adaptive immunity
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This document provides an overview of Tajuddin's presentation on adaptive immunity. It discusses the cells and organs involved in adaptive immunity, including B cells and T cells that mature in the bone marrow and thymus respectively. It describes humoral and cell-mediated immunity and the roles of antibodies and T cells. Key topics covered include antigen receptors, cytokines, active and passive immunity, immunoglobulin classes, complement activation, and the differences between T-dependent and T-independent antigens.
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Adaptive immunity
- 2. ∗Department: Microbiology ∗Semester: 2nd ∗Class no: 02 Tajuddin
- 4. ∗ Body defense mechanisms & its characteristics ∗ Adaptive immunity & Its responses to antigens ∗ Cells of Adaptive Immune Response ∗ Organs of Immune Responses ∗ Types of Adaptive immunity ∗ Role of Antigens receptors & Cytokines in Immune Response ∗ T-Dependent Vs T-Independent Antigens Over view of Presentation
- 5. Immune system depend us from
- 6. Defense Mechanisms 1.External defense 2.Internal Defense 3.Immune Defense
- 7. Characteristics of Adaptive Immunity •Recognition of self versus non- self •Response is specific •Retains a “memory” allowing an accelerated second response •Can respond to many different materials
- 8. Acquired immunity (Adaptive or Specific) Humoral Immunity Cell mediated Immunity Acquired (Adaptive) Immunity
- 9. ∗ The adaptive or specific immune response involves two main lines of defence: humoral immunity and cell mediated immunity. ∗ Humoral immunity involves Blymphocytes (Bcells) ∗ Cell-mediated immunity involves T lymphocytes (T cells) ∗ Both B cells and T cells are derived from stem cells in the bone marrow, however they mature in different parts of the body. ∗ Bcells mature in the bone marrow then travel to lymphatic tissues, especially the spleen and lymph nodes ∗ T cells mature in the thymus Humoral and cell-mediated immunity
- 11. Immune System Response to Antigens Humoral Immunity •Involves antibodies (secreted from B cells) dissolved in the blood plasma. •Demonstrated as an immune response using only the blood serum(Plasma without clotting protiens). •Defense against bacteria, bacterial
- 12. Cell-Mediated Immunity •Involves the activities of specific white blood cells (T cells). •Defense against cancer cells, virus- infected cells, fungi, animal parasites, & foreign cells from transplants. Immune System Response to Antigens (cont.)
- 14. Cells involved in specific immune mechanisms are: I) Hematopoitic leucocytes(derived from mesoderm) 1- Lymphoid * T-lymphocytes: - Antigen specific cells carrying CD3 complex, CD4, CD8 - Dominant blood lymphocytes (70%) - Produce cytokines - Activation of other cells (Th CD4) - Suppressors for others (Ts CD8) Cells Of Immune Response
- 15. * B-lymphocytes: - Antigen specific cells with surface receptor - Less common lymphocytes (20%) - Responsible for antibody production * NK, K cells: - Not antigen specific - Carry Fc receptors , NK-target cell receptor Cells Of Immune Response (cont.)
- 16. 2- Monocytic myeloid a- Monocyte-tissue macrophages: . Non specific . Carry Fc receptors . Phagocytic . Antigen processing and presenting cells . Produce cytokines b- Neutrophils: . Non specific . Carrying Fc, complement molecules Cells of Immune Response (cont.) 16
- 17. Cells of Immune Response (cont.) c- Eosinophil: . Non specific . Carrying Fc receptor . Produce allergic mediators d- Basophils and Mast cells: . Non specific . Carrying Fc receptors . Produce allergic mediators17
- 18. ІІ-Non hematopoietic cells: - Dendritic cells - Astrocytes and - Endothelial cells Function : antigen presentation Cells of Immune Response (cont.)
- 19. Cells of the immune systemBone graft Multipotential stem cell Hematopoietic stem cell Platelets Macrophage Erythrocytes Eosinophil Neutrophil Megakaryocyte Mast cell Basophil T lymphocyte Natural killer cell Dendritic cell B lymphocyte Lymphoid progenitor cell Myeloid progenitor cell Monocyte Marrow Bone 19
- 20. Tonsils and adenoids Lymph nodes Appendix Lymphatic vessels Lymph nodes Thymus Peyer’s patches Spleen Lymphatic vessels Lymph nodes Organs of the Immune Response • The organs of our immune system are positioned throughout our body. • They are called lymphoid organs because they are home to lymphocytes--the white blood cells that are key operatives of the immune system. Within these organs, the lymphocytes grow, develop, and are deployed. • Key organs include the bone marrow, the thymus and the spleen. • In addition to these organs, clumps of lymphoid tissue are found in many parts of the body, especially in the linings of the digestive tract and the airways and lungs-- gateways to the body. These tissues include the tonsils, adenoids Bone marrow
- 21. ∗ The production of antibodies against a specific disease by the immune system. ∗ Naturally acquired through disease ∗ Artificially acquired through vaccination ∗ Vaccines include inactivated toxins, killed microbes, parts of microbes, and viable but weakened microbes. ∗ Active immunity is usually permanent Active Immunity
- 22. ∗ A vaccinated person has a secondary response based on memory cells when encountering the specific pathogen. ∗ Routine immunization against infectious diseases such as measles and whooping cough, and has led to the eradication of smallpox, a viral disease. ∗ Unfortunately, not all infectious agents are easily managed by vaccination. Active Immunity (cont.)
- 23. ∗Passive Immunity- Protection against disease through antibodies produced by another human being or animal. ∗Effective, but temporary ∗Maternal antibodies (IgG) ∗Colostrum (IgA) Passive Immunity
- 24. ∗Passive immunity can be transferred artificially by injecting antibodies from an animal that is already immune to a disease into another animal. ∗ Rabies treatment: injection with antibodies against rabies virus that are both passive immunizations (the immediate fight) and active immunizations (longer term Passive Immunity (Cont.)
- 25. B Cells •Mature in bone marrow •Involved in humoral immunity •Once activated by antigen, proliferate into two clones of cells: plasma cells that secrete antibodies and memory cells that may be converted into plasma cells at a later time
- 26. B Cells
- 27. Release of Antibodies from Plasma cell
- 28. ∗ Antibodies constitute a group of globular proteins called immunoglobins (Igs). ∗ A typical antibody molecule has two identical antigen-binding sites specific for the epitope that provokes its production. Antibodies
- 30. Immunoglobin Classes IgM • 1st response to antigen • Can’t cross placenta •Involved in agglutination and complement activation IgG • Most common form • Crosses blood vessels • Crosses placenta (passive immunity to fetus) •Involved in agglutination and complement activation IgA • Secreted from mucus membranes • Prevents attachment of bacteria to epithelial surface • In colostrum • Important in mucosal immunity IgD • B cell activation • Can’t cross placenta •Important in development of the immune response IgE • Histamine reactions and allergies •Attaches to mast cells
- 31. Mechanisms on Antibody Action cipitation of soluble antigens glutination of foreign cells utralization hanced phagocytosis mplement activation leading to cell lysis mulates inflammation
- 32. ∗ The binding of antibodies to antigens to form antigen-antibody complexes is the basis of several antigen disposal mechanisms. 32
- 33. The classical complimentary pathway, resulting in lysis of a target cell
- 34. T Cells •Mature in thymus •Involved in cell-mediated immunity •Activated when another cell presents antigen to them •Several types of T cells: cytotoxic T cells, helper T cells, suppressor T cells, and memory T cells
- 35. • There are two main types of T cells, and each responds to one class of MHC molecule. – Cytotoxic T cells (TC) have antigen receptors that bind to protein fragments displayed by the body’s class I MHC molecules. – HelperT cells (TH) have receptors that bind to peptides displayed by the body’s class II MHC molecules. T Cells
- 36. The central role of helperT cells
- 37. Role of antigen receptors in the immune response • Both B cells and T cells carry customized receptor molecules that allow them to recognize and respond to their specific targets. • The Bcell’s antigen-specific receptorthat sits on its outersurface is also a sample of the antibody it is prepared to manufacture; this antibody-receptor recognizes antigen in its natural state. • The T cell’s receptor systems are more complex. T cells can recognize an antigen only afterthe antigen is processed and presented in combination with a special type of majorhistocompatibility complex (MHC) marker. • Killer T cells only recognize antigens in the grasp of Class I MHC markers, while helper T cells only
- 38. Antigen receptors Killer cell Infected cellAntigen-presenting cell Antigen-presenting cell CD8 protein Cell membrane MHC Class I MHC Class I Antigenic peptide T cell receptorCD4 protein Cell membrane MHC Class II Antigenic peptide T cell receptor Cell membrane Antigen Antigen- specific receptor B cell Killer cell Infected cellAntigen-presenting cell Antigen-presenting cell CD8 protein Cell membrane MHC Class I MHC Class I Antigenic peptide T cell receptorCD4 protein Cell membrane MHC Class II Antigenic peptide T cell receptor Cell membrane Antigen Antigen- specific receptor Helper T cellB cell
- 39. Role of cytokines in immune response • Cytokines are diverse and potent chemical messengers secreted by the cells of immune system. They are the chief communication signals of our T cells. Cytokines include interleukins, growth factors, and interferon. • Lymphocytes, including both T cells and B cells, secrete cytokines called lymphokines, while the cytokines of monocytes and macrophages are dubbed monokines. Many of these cytokines are also known as interleukins because they serve as a messenger between white cells, or leukocytes. • Interferon are naturally occurring cytokines that may boost the immune system’s ability to recognize cancer as a foreign invader. • Binding to specific receptors on target cells, cytokines recruit many other cells and substances to the field of action. Cytokines encourage cell growth, promote cell activation, direct cellular traffic, and destroy target cells--including cancer cells. • When cytokines attract specific cell types to an area, they are called chemokines. These are released at the site of injury or infection and
- 41. ∗T-independent antigens ∗T cells activated by binding to certain antigens ∗No memory cells generated ∗Weaker response than t-dependent ∗T-dependent antigens ∗Most antigens require co-stimulation to evoke a B-cell response ∗Antibody production stimulated with
- 42. Overview of Immune System Responses
Editor's Notes
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- <number> Cells destined to become immune cells, like all blood cells, arise in your body’s bone marrow from stem cells. Some develop into myeloid progenitor cells while others become lymphoid progenitor cells. The myeloid progenitors develop into the cells that respond early and nonspecifically to infection. Neutrophils engulf bacteria upon contact and send out warning signals. Monocytes turn into macrophages in body tissues and gobble up foreign invaders. Granule-containing cells such as eosinophils attack parasites, while basophils release granules containing histamine and other allergy-related molecules. Lymphoid precursors develop into the small white blood cells called lymphocytes. Lymphocytes respond later in infection. They mount a more specifically tailored attack after antigen-presenting cells such as dendritic cells (or macrophages) display their catch in the form of antigen fragments. The B cell turns into a plasma cell that produces and releases into the bloodstream thousands of specific antibodies. The T cells coordinate the entire immune response and eliminate the viruses hiding in infected cells.
- <number> The organs of your immune system are positioned throughout your body. They are called lymphoid organs because they are home to lymphocytes--the white blood cells that are key operatives of the immune system. Within these organs, the lymphocytes grow, develop, and are deployed. Bone marrow, the soft tissue in the hollow center of bones, is the ultimate source of all blood cells, including the immune cells. The thymus is an organ that lies behind the breastbone; lymphocytes known as T lymphocytes, or just T cells, mature there. The spleen is a flattened organ at the upper left of the abdomen. Like the lymph nodes, the spleen contains specialized compartments where immune cells gather and confront antigens. In addition to these organs, clumps of lymphoid tissue are found in many parts of the body, especially in the linings of the digestive tract and the airways and lungs--gateways to the body. These tissues include the tonsils, adenoids, and appendix.
- <number> I. DEFINITION Immunoglobulins (Ig) Glycoprotein molecules that are produced by plasma cells in response to an immunogen and which function as antibodies. The immunoglobulins derive their name from the finding that they migrate with globular proteins when antibody-containing serum is placed in an electrical field (Figure 1). II. GENERAL FUNCTIONS OF IMMUNOGLOBULINS A. Antigen binding Immunoglobulins bind specifically to one or a few closely related antigens. Each immunoglobulin actually binds to a specific antigenic determinant. Antigen binding by antibodies is the primary function of antibodies and can result in protection of the host. The valency of antibody refers to the number of antigenic determinants that an individual antibody molecule can bind. The valency of all antibodies is at least two and in some instances more. B. Effector Functions Frequently the binding of an antibody to an antigen has no direct biological effect. Rather, the significant biological effects are a consequence of secondary "effector functions" of antibodies. The immunoglobulins mediate a variety of these effector functions. Usually the ability to carry out a particular effector function requires that the antibody bind to its antigen. Not every immunoglobulin will mediate all effector functions. Such effector functions include: 1. Fixation of complement - This results in lysis of cells and release of biologically active molecules (see chapter two) 2. Binding to various cell types - Phagocytic cells, lymphocytes, platelets, mast cells, and basophils have receptors that bind immunoglobulins. This binding can activate the cells to perform some function. Some immunoglobulins also bind to receptors on placental trophoblasts, which results in transfer of the immunoglobulin across the placenta. As a result, the transferred maternal antibodies provide immunity to the fetus and newborn Immunoglobulin classes IgM First response to antigen IgG Most common form IgA Secreted form IgD B cell activation IgE Histamine reactions and allergies
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- <number> Both B cells and T cells carry customized receptor molecules that allow them to recognize and respond to their specific targets. The B cell’s antigen-specific receptor that sits on its outer surface is also a sample of the antibody it is prepared to manufacture; this antibody-receptor recognizes antigen in its natural state. The T cell’s receptor systems are more complex. T cells can recognize an antigen only after the antigen is processed and presented in combination with a special type of major histocompatibility complex (MHC) marker. Killer T cells only recognize antigens in the grasp of Class I MHC markers, while helper T cells only recognize antigens in the grasp of Class II MHC markers. This complicated arrangement assures that T cells act only on precise targets and at close range.
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