Immunology

1. Immunology Chapter 43

2. Immune System • A wide variety of pathogens (including parasites) think that animal hosts are excellent habitats and very tasty • To stop from becoming a bacterial hotel, animals have ways to fight back • Most critical component – know self from non-self cells and tissues • Next, know how to kill the invaders without harming yourself

3. Two main components of vertebrate immune response:

4. Why is the innate immune response critical ? Time!

5. Innate Immunity - External • Skin • Barrier, oil glands and sweat modify pH, salt level • Mucous Membranes • Barrier, mucous traps and cilia removes particles • Secretions • Stomach acid, lysozyme

6. Innate Immunity – Internal • Phagocytic cells • Recognize non-self • Phagocytosis – engulf invader • Digest and display

9. Innate Immunity – Internal • Phagocytic cells • Recognize non-self • Phagocytosis – engulf invader • Digest and display • Antimicrobial proteins • Defensins, etc. - lysis of bacterial walls • Complement – lysis by cascade

11. Innate Immunity – Internal • Phagocytic cells • Recognize non-self • Phagocytosis – engulf invader • Digest and display • Antimicrobial proteins • Defensins, etc. lysis of bacterial walls • Complement – lysis by cascade • Inflammatory response • Injury causes release of signals (eg. Histamines) which increase blood flow to site • Causes heat and swelling

12. Neutrophils and Mac’s eat em’ up Chemical signals released by mac’s and mast cells Chemokines released, attract more cells Capillaries get leaky, agents move from blood to site

13. Innate Immunity – Internal • Natural killer cells • Recognize and attack infected cells or cancer cells • Surface receptors recognize foreign antigens on self cell • NK attach and kill target cell (apoptosis) • Invertebrate Immunity • Only innate but still complex • Has recognition factors and antibacterials

14. Two main components of vertebrate immune response:

15. Acquired Immunity • Lymphocyte • White blood cell that recognizes specific component (usually protein) of an invader • Antigen • Any foreign component that can elicit an immune response • T cells • Develop in thymus, recognize antigens by specific receptor (T cell receptor) • B cells • Develop in bone marrow, recognize antigen by specific receptor (B cell receptor)

18. Specificity –what does he mean by that? • Do T cells and B cells have specific receptors?

20. Specificity –what does he mean by that? • Do T cells and B cells have specific receptors? • They have different types of receptors • Each cell’s receptors recognize only one antigen • Your lymphocytes can recognize thousands of antigens, only one antigen/clone • There are many of each clone in your bloodstream or lymph nodes

21. Humoral Immunity • Antigen presenting cell contacts and activates helper T cells • Cytokines (protein signals) released • Eg. interleukins • B and T cells activated

23. Humoral Immunity • Antigen presenting cells contacts and activates helper T cells • Cytokines (protein signals) released • B and T cells activated • Cell binding produces greater response

25. Humoral Immunity • Antigen presenting cells contacts and activates helper T cells • Cytokines (protein signals) released • B and T cells activated • Cell binding produces greater response • B cells divide (clones) • B-cells release antibody (Plasma cells) • Memory cells saved for later

26. Bacterium Macrophage Peptide antigen Class II MHCmolecule B cell Secreted antibodymolecules Clone of plasma cells CD4 TCR Endoplasmicreticulum of plasma cell Cytokines Helper T cell Activated helper T cell Clone of memoryB cells 3 1 2

28. Cell-mediated Immunity • Cytotoxic T cells recognize infected self cells • Bind to cell and initiate apoptosis (process of cell self-destruction)

29. The granzymes initiate apoptosis within the target cells, leading to fragmentation of the nucleus, release of small apoptotic bodies, and eventual cell death. The released cytotoxic T cell can attack other target cells. A specific cytotoxic T cell binds to a class I MHC–antigen complex on a target cell via its TCR with the aid of CD8. This interaction, along with cytokines from helper T cells, leads to the activation of the cytotoxic cell. The activated T cell releases perforin molecules, which form pores in the target cell membrane, and proteolytic enzymes (granzymes), which enter the target cell by endocytosis. Cytotoxic T cell Released cytotoxic T cell Perforin Cancer cell Granzymes Apoptotic target cell TCR CD8 Class I MHC molecule Pore Target cell Peptide antigen Cytotoxic T cell 2 1 2 3 1 3

33. Antibodies • Soluble proteins that recognize antigens on invaders • Found in blood, mucus, and mother’s milk • Antibody binding neutralizes invaders or activates immune response

35. Immunity • Active Immunity • Produced by contact with an infectious agent • Can be natural (poked with a stick) or artificial (stuck with a needle - vaccination) • See Jenner, milkmaids, and cowpox • Passive Immunity • Transfer of serum from survivor to you • Eg. Mother’s milk, snake anti-venom

36. Acquired Immunodeficiency Syndrome (AIDS) • Human immunodeficiency virus (HIV) infects and kills helper T cells

38. Acquired Immunodeficiency Syndrome (AIDS) • Human immunodeficiency virus (HIV) infects and kills helper T cells • HIV is an RNA virus, it mutates rapidly • Once in your cells it incorporates into your DNA • Transmission requires someone’s body fluid getting into you

41. Herpes virus – fast growth, bursts cell quickly

42. AIDS Virus – Slow growth, maximum virus production