1 / 66

The Concept of Immunity

The Concept of Immunity. Immunity : Latin immunis , exempt Susceptibility : Lack of resistance to a disease, also known as Vulnerability Innate immunity : Inborn Adaptive immunity : Acquired, resistance to a specific pathogen. An Overview of the Body’s Defenses.

kara
Download Presentation

The Concept of Immunity

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Concept of Immunity • Immunity: Latin immunis, exempt • Susceptibility: Lack of resistance to a disease, also known as Vulnerability • Innate immunity: Inborn • Adaptive immunity: Acquired, resistance to a specific pathogen

  2. An Overview of the Body’s Defenses ANIMATION Host Defenses: The Big Picture Figure 16.1

  3. First Line of Defense: I. Skin & Mucous Membranes • Skin • Keratin, a protective protein • Mucous membranes • Hairs • Cilia • Tears, Saliva, Urine, Vaginal secretions • Lysozyme

  4. Ciliary Escalator Figure 24.7

  5. II. Normal Microbiota • Normal microbiota compete with pathogens for nutrients • Keep pH unfavorable for disease microbes

  6. Second Line of DefenseI. Blood components

  7. Differential White Cell Count • Percentage of each type of white cell in a sample of 100 white blood cells • Early and late in infection: Neutrophil then Macrophage

  8. II. Lymphatic SystemTissue + Fluid Figure 16.5a

  9. III. Phagocytosis • Neutrophils • Macrophage • Presents Ag • Secret cytokines (lymphokines + interleukins) Figure 16.6

  10. IV. Inflammation • Releasing histamine • Vasodilation (histamine, kinins, prostaglandins, and leukotrienes) • Redness • Swelling • Pain • Heat • Tissue repair and wall-off

  11. Fever • Abnormally high body temperature • Body’s defensive mechanism • Increase enzyme activity and cytokine activity • Increase blood flow • Some bacteria can not survive at higher temperature • Disadvantage: • Tachycardia • Acidosis • Dehydration • 44–46°C fatal

  12. V. Antimicrobial Substances • Complements C3a + C5a cause inflammation C5b + C6 + C7 + C8 + C9 cause cell lysis

  13. V. Antimicrobial Substances • Interferons • a- and b- interferon: Virus infected cells to produce AVPs • g- interferon: Neutrophils and macrophages • Limitations: • Side effects • Short lived • Only prevents, not stop viral synthesis • No effect on a number of cancers • Ion-binding Proteins • AMPs: Natural antibiotics

  14. Types of Adaptive Immunity • Naturally acquired active immunity • Resulting from infection • Naturally acquired passive immunity • Transplacental or via colostrum • Artificially acquired active immunity • Injection of Ag (vaccination) • Artificially acquired passive immunity • Injection of Ab

  15. Dual Nature of Adaptive Immunity Figure 17.8

  16. Dual Nature of Adaptive Immunity • Humoral immunity: • B-cells • Ag-Ab • Cellular immunity • T-cells • Cytokines ANIMATION Humoral Immunity: Overview

  17. I. Antigens • It has to be large • Ag determinants = epitopes • Haptenand Carrier

  18. Antigens Figure 17.1

  19. Haptens Figure 17.2

  20. II. Antibodies • They are immunoglobulins (Ig) • The antigen-binding sitesrecognize epitope and determine valence • Constant Region / Variable Region • Heavy Chain / Light Chain

  21. Antibodies Figure 17.3a,b

  22. IgG Antibodies • Monomer • Most common and abundant (80%) • Fix complement • Cross placenta • Enhance phagocytosis; neutralize toxins and viruses; protects fetus and newborn • Half-life = 23 days

  23. IgM Antibodies • Pentamer • Agglutination • Fix complement • Agglutinates microbes; first Ab produced in response to infection • Half-life = 5 days

  24. IgA Antibodies • Dimer • 10–15% of serum Abs • In secretions • Mucosal protection • Half-life = 6 days

  25. IgD Antibodies • Monomer • In blood, in lymph, and on B cells • On B cells, initiate immune response • Half-life = 3 days

  26. IgE Antibodies • Monomer • Allergic reactions; lysis of parasitic worms • Half-life = 2 days

  27. III. B Cells • Diversity • Self – non-self discrimination • Memory

  28. 1st exposure to Ag First Clones 2nd exposure to Ag

  29. T-independent Activation of B Cells Figure 17.6

  30. T-dependent Activation of B Cells Figure 17.4

  31. Clonal Selection ANIMATION Humoral Immunity: Clonal Selection and Expansion Figure 17.5

  32. Clonal deletion:eliminates harmful B cells

  33. Immune Responses to an Antigen Figure 17.16

  34. Immune Responses to an Antigen

  35. Monoclonal Ab Production

  36. The Results of Ag-Ab Binding Destroy Made unavailable Figure 17.7

  37. IV. Cellular Immunity • T cells mature in the thymus • Thymic selection eliminates many immature T cells • T cells respond to Ag by T-cell receptors (TCRs) • T cells require antigen-presenting cells (APCs)

  38. T Helper Cells • CD4+ or TH cells (When activated) • Produce cytokines • Help in B cell and Tc cell activation

  39. T Cytotoxic Cells • CD8+or TC cells • Target cells are self carrying endogenous antigens • Activated into cytotoxic T lymphocytes (CTLs) • CTL causes apoptosis

  40. T Cytotoxic Cells Figure 17.11

  41. T Regulatory Cells • Treg cells • CD4 and CD25 on surface • Suppress T cells against self

  42. Antigen-Presenting Cells • Digest antigen • Ag fragments on APC surface with MHC • B cells • Dendritic cells • Activated macrophages ANIMATION Antigen Processing and Presentation: MHC

  43. A Dendritic Cell Figure 17.13

  44. Activated Macrophages Figure 17.14

  45. Natural Killer (NK) Cells • Granular leukocytes destroy cells that don’t express MHC I • Kill virus-infected and tumor cells • Attack parasites

  46. Cells Communicate via Cytokines

More Related