1. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 13 Innate and Adaptive Immunity

2. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Immune Response Definition –The collective, coordinated response of the cells and molecules of the immune system Types of Immune Defenses –Innate or nonspecific immunity: the natural resistance with which a person is born –Adaptive or specific immunity: the second line of defense, responding less rapidly than innate immunity but more effectively

3. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Principal Cells of the Immune System Lymphocytes –Cells that specifically recognize and respond to foreign antigens Accessory cells –Macrophages and dendritic cells –Function as antigen-presenting cells by the processing of a complex antigen into epitopes required for the activation of lymphocytes

4. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Mediators of the Immune System Cytokines—soluble proteins secreted by cells of both the innate and adaptive immunity Chemokines—cytokines that stimulate the migration and activation of immune and inflammatory cells Colony-stimulating factors—stimulate the growth and differentiation of bone marrow progenitors of immune cells

5. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Innate Immunity Components –Epithelial barriers –Phagocytic cells Neutrophils and macrophages –NK cells –Plasma proteins –Opsonins, cytokines, and acute-phase proteins Induction of inflammatory response

6. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Soluble Mediators of Innate Immunity Opsonins—facilitation of phagocytosis –Acute-phase reactants, lectins, complement proteins –IgG and IgM with adaptive immunity Cytokines—TNF, interleukins, interferons, and chemokines Acute-phase proteins –Mannose-binding ligand and C-reactive protein Complement system –Cytolysis, opsonization, chemotaxis, anaphylaxis

7. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Innate Recognition Systems Pattern recognition receptors (PRRs) Pathogen-associated molecular patterns (PAMPs) Toll-like receptors (TLRs)

8. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins The Complement System The complement system is found in the blood and is essential for the activity of antibodies. Activation of the complement system increases bacterial aggregation, which renders them more susceptible to phagocytosis.

9. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Adaptive Immunity Able to recognize and react to a large number of microbes and nonmicrobial substances Ability to distinguish among different, even closely related, microbes and molecules and to “remember” the pathogen by quickly producing a heightened immune response on subsequent encounters Lymphocytes and their products Antigen identification

10. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Types of Adaptive Immune Responses Humoral Immunity –Mediated by molecules in the blood –The principal defense against extracellular microbes and toxins Cell-Mediated Immunity or Cellular Immunity –Mediated by specific T lymphocytes –Defends against intracellular microbes such as viruses

11. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Two Types of Immune Cells Regulatory Cells –Assist in orchestrating and controlling the immune response Effector Cells –Accomplish the final stages of the immune response with the elimination of the antigen –Activated T lymphocytes, mononuclear phagocytes, and other leukocytes function as effector cells in different immune responses.

12. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Antigens and Antibodies Antigens are substances foreign to the host that can stimulate an immune response. Antibodies—recognize antigens –Receptors on immune cells –Secreted proteins

13. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Types of Antigens Bacteria Fungi Viruses Protozoa Parasites Nonmicrobial agents

14. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Properties of MHC Molecules HLA Antigens –Class I: HLA-A, HLA-B, HLA-C –Class II: HLA-DR, HLA-DP, HLA-DQ Distribution –Class I: virtually all nucleated cells –Class II: restricted to immune cells, antigen- presenting cells, B cells, and macrophages

15. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Is the following statement true or false? The function of MHC molecules is to mark foreign proteins, rendering them antigenic.

16. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer False Rationale: The MHC molecules are used by the immune cells to differentiate host tissue from foreign tissue. They are found on all host tissues.

17. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Properties of MHC Molecules (cont.) Functions –Class I: present processed antigen to cytotoxic CD8 + T cells; restrict cytolysis to virus-infected cells, tumor cells, transplanted cells –Class II: present processed antigenic fragments to CD4 + T Cells; necessary for effective interaction among immune cells

18. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Antigen Presentation Macrophages and dendritic cells process and present antigen peptides to CD4 + helper T cells. Capture antigens and then enable their recognition by T cells Initiation of adaptive immunity

19. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Lymphocytes B cells –Humoral immunity –Memory T cells –Cell-mediated immunity –Memory

20. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Identifying Factors of B Lymphocytes Presence of membrane immunoglobulin that functions as the antigen receptor Class II MHC proteins Complement receptors Specific CD molecules

21. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Functions of T Lymphocytes The activation of other T cells and B cells The control of intracellular viral infections The rejection of foreign tissue grafts Delayed hypersensitivity reactions

22. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Classes and Functions of Immunoglobulins IgG: displays antiviral, antitoxin, and antibacterial properties, responsible for protection of newborn; activates complement, and binds to macrophages IgA: predominant Ig in body secretions; protects mucous membranes IgM: forms natural antibodies; prominent in early immune responses, activates complement

23. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Classes and Functions of Immunoglobulins (cont.) IgD: found on B lymphocytes, needed for maturation of B cells IgE: binds to mast cells and basophils; involved in parasitic infections, allergic and hypersensitivity reactions

24. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Functions of the Lymphoid Organs Central lymphoid organs (bone marrow and the thymus) –Provide the environment for immune cell production and maturation Peripheral lymphoid organs –Function to trap and process antigen and promote its interaction with mature immune cells

25. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Functional Groups of Cytokines One group of cytokines (e.g., IL-1, IL-6, TNF) mediates inflammation by producing fever and the acute-phase response and by attracting and activating phagocytes (e.g., IL-8, IFN-γ). Other cytokines are maturation factors for the hematopoiesis of white or red blood cells (e.g., IL-3, granulocyte–macrophage colony-stimulating factor [GM- CSF]).

26. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Immune Response Active Immunity –Specific protection induced following exposure to antigens Passive Immunity –Specific protection induced through transfer of protective antibodies against an antigen –Transferred from another source Maternal IgG crosses the placenta and protects the newborn during the first few months of life. IgA in colostrum

27. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Which type of immunity is characterized by the development of a specific response to an antigen? −A. Innate immunity −B. Acquired immunity −C. Autoimmunity −D. Alloimmunity

28. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer B. Acquired immunity Rationale: Acquired immunity is the response to an antigen. The body develops humoral and cell-mediated immune responses.

29. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Development of an Immune Response Fetal development at 5 to 6 weeks Secondary lymphoid organs well developed at birth IgA and IgM shortly after birth –Reach adult levels by 1 year of age

30. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins The Elderly Immune System Declining ability to adapt to environmental stresses –Decline in immune responsiveness –Decrease in the size of the thymus gland –Biological clock in T cells –Altered responses of the immune cells to antigen stimulation

31. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Question The aging immune system is less responsive due to which of the following? −A. Decline in immune responsiveness −B. Decrease in the size of the thymus gland −C. Biological clock in T cells −D. Altered responses of the immune cells to antigen stimulation −E. All of the above are possibilities.

32. Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer E. All of the above are possibilities.