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© 2014 Pearson Education, Inc. 35 Immunity. © 2014 Pearson Education, Inc. Overview: Recognition and Response Pathogens - agents that cause disease, All.

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Presentation on theme: "© 2014 Pearson Education, Inc. 35 Immunity. © 2014 Pearson Education, Inc. Overview: Recognition and Response Pathogens - agents that cause disease, All."— Presentation transcript:

1 © 2014 Pearson Education, Inc. 35 Immunity

2 © 2014 Pearson Education, Inc. Overview: Recognition and Response Pathogens - agents that cause disease, All animals and plants have innate immunity Vertebrates also have adaptive immunity

3 © 2014 Pearson Education, Inc. Figure 35.1

4 © 2014 Pearson Education, Inc. Innate immunity involves nonspecific responses to pathogens consists of external barriers plus cellular and chemical defenses Innate Immunity

5 © 2014 Pearson Education, Inc. Adaptive (acquired) immunity develops after exposure It involves a very specific response to pathogens Adaptive Immunity

6 © 2014 Pearson Education, Inc. Figure 35.2 INNATE IMMUNITY (all animals) Recognition of traits shared by broad ranges of pathogens, using a small set of receptors Rapid response Barrier defenses: Skin Mucous membranes Secretions Internal defenses: Phagocytic cells Natural killer cells Antimicrobial proteins Inflammatory response Humoral response: Antibodies defend against infection in body fluids. Cytotoxic cells defend against infection in body cells. Cell-mediated response: ADAPTIVE IMMUNITY (vertebrates only) Recognition of traits specific to particular pathogens, using a vast array of receptors Slower response Pathogens (such as bacteria, fungi, and viruses)

7 © 2014 Pearson Education, Inc. Figure 35.3 Pathogen Vacuole PHAGOCYTIC CELL Lysosome containing enzymes Pseudopodia surround pathogens. engulfed by endocytosis. Pathogens Vacuole forms. Vacuole and lysosome fuse. Pathogens destroyed. Debris from pathogens released. 1 2 3 4 5 6

8 © 2014 Pearson Education, Inc. Cellular Innate Defenses 2 mammalian phagocytic cells –Neutrophils in blood –Macrophages throughout the body

9 © 2014 Pearson Education, Inc. Vertebrate natural killer cells - detect abnormal cells & release chemicals leading to cell death. Many cellular innate defenses involve the lymphatic system

10 © 2014 Pearson Education, Inc. Antimicrobial Peptides and Proteins Interferons interfere with viruses and activate macrophages The complement system … 30 proteins activated by microbe surface substances and lead to lysis of invaders

11 © 2014 Pearson Education, Inc. Inflammatory Response inflammatory response, (pain swelling redness heat) Mast cells release histamine, making blood vessels more permeable macrophages and neutrophils release cytokines, promoting blood flow to the site of injury

12 © 2014 Pearson Education, Inc. Figure 35.5-1 Pathogen Splinter Macro- phage Capillary Neutrophil Red blood cells Mast cell Signaling molecules 1 Histamines and cytokines released. Capillaries dilate.

13 © 2014 Pearson Education, Inc. Figure 35.5-2 Pathogen Splinter Macro- phage Capillary Neutrophil Red blood cells Mast cell Signaling molecules 1 Histamines and cytokines released. Capillaries dilate. Movement of fluid Antimicrobial peptides enter tissue. Neutrophils are recruited. 2

14 © 2014 Pearson Education, Inc. Figure 35.5-3 Pathogen Splinter Macro- phage Capillary Neutrophil Red blood cells Mast cell Signaling molecules 1 Histamines and cytokines released. Capillaries dilate. Movement of fluid 2 Antimicrobial peptides enter tissue. Neutrophils are recruited. Phagocytosis 3 Neutrophils digest pathogens and cell debris. Tissue heals.

15 © 2014 Pearson Education, Inc. adaptive immunity, pathogen-specific recognition The adaptive response relies on B and T lymphocytes, T cells mature in thymus B cells mature in bone marrow Antigens – substances that elicit a response when bound to an antigen receptor on or from a B or T cell There are millions of different antigen receptors but on a single B cell or T cell all are identical

16 © 2014 Pearson Education, Inc. Figure 35.UN01 Antigen receptors Mature B cellMature T cell

17 © 2014 Pearson Education, Inc. Figure 35.6 Antigen- binding site B cell antigen receptor Disulfide bridge Light chain Antigen- binding site Variable regions Constant regions Transmembrane regions Plasma membrane Heavy chains Cytoplasm of B cell B cell V V C C C C V V

18 © 2014 Pearson Education, Inc. B cell activation can release a soluble form of the protein called an antibody or immunoglobulin (Ig) antibodies, rather than B cells themselves, defend against pathogens

19 © 2014 Pearson Education, Inc. Figure 35.7 Antigen- receptor Antibody B cell Antigen Epitope Pathogen (a) B cell antigen receptors and antibodies Antibody C Antibody A Antibody B Antigen (b) Antigen receptor specificity

20 © 2014 Pearson Education, Inc. Figure 35.8 Antigen- binding site T cell antigen receptor Disulfide bridge T cell Cytoplasm of T cell  chain  chain Variable regions Constant regions Transmembrane region Plasma membrane VV CC

21 © 2014 Pearson Education, Inc. T cells bind to antigen fragments presented on host cell MHC (major histocompatibility complex) -host proteins that display the antigen fragments on cell surface

22 © 2014 Pearson Education, Inc. In infected cells, antigens are cut up by enzymes MHC molecules transport antigen fragments to the cell surface, (antigen presentation) A T cell can then bind both the antigen fragment and the MHC molecule This interaction is necessary for the T cell to participate in the adaptive immune response

23 © 2014 Pearson Education, Inc. Figure 35.9 Host cell Displayed antigen fragment MHC molecule Antigen fragment Pathogen T cell T cell antigen receptor

24 © 2014 Pearson Education, Inc. B and T Cell Diversity immune system assembles a diverse variety of antigen receptors by rearrangement of the DNA

25 © 2014 Pearson Education, Inc. Figure 35.10 pre-mRNA mRNA DNA of differentiated B cell DNA of undifferentiated B cell RNA processing Transcription of permanently rearranged, functional gene Recombination deletes DNA between randomly selected V segment and J segment Functional gene 1 2 3 4 Translation Light-chain polypeptide Variable region Constant region B cell Antigen receptor V C C Cap V 39 J5J5 Poly-A tail V V V V C CC C C V 39 J5J5 Intron C V 39 J5J5 Intron V 38 V 37 V 39 V 38 V 40 V 37 J5J5 J4J4 J3J3 J2J2 J1J1 Intron C

26 © 2014 Pearson Education, Inc. Figure 35.10a DNA of undifferentiated B cell V 39 V 38 V 40 V 37 J5J5 J4J4 J3J3 J2J2 J1J1 Intron DNA of differentiated B cell pre-mRNA Transcription of permanently rearranged, functional gene Recombination deletes DNA between randomly selected V segment and J segment Functional gene C V 39 V 38 V 37 J5J5 Intron C C V 39 J5J5 21

27 © 2014 Pearson Education, Inc. Figure 35.10b pre-mRNA Intron C V 39 J5J5 mRNA RNA processing C Cap V 39 J5J5 Poly-A tail Translation Light-chain polypeptide Variable region Constant region B cell Antigen receptor V C V V V V C C C C 43

28 © 2014 Pearson Education, Inc. Self-Tolerance As lymphocytes mature they are tested, self- reactive ones are eliminated

29 © 2014 Pearson Education, Inc. Activated B or T cells divide producing clones (called clonal selection) Two types produced –Short-lived effector cells - act immediately against the antigen –Long-lived memory cells – can produce effector cells if the same antigen is encountered again

30 © 2014 Pearson Education, Inc. Figure 35.11 B cells that differ in antigen specificity Antigen Antigen receptor Antibody Plasma cellsMemory cells

31 © 2014 Pearson Education, Inc. 1 st exposure - primary immune response B and T cells give rise to their effector forms Later exposures - secondary immune response, memory cells facilitate a faster, stronger, and longer response Immunological memory can span many decades Immunological Memory

32 © 2014 Pearson Education, Inc. Figure 35.12 Primary immune response to antigen A Secondary immune response to antigen A Antibodies to A Antibodies to B 10 1 10 3 10 4 10 0 0714212835424956 Primary immune response to antigen B Antibody concentration (arbitrary units) Exposure to antigen A Exposure to antigens A and B Time (days) 10 2

33 © 2014 Pearson Education, Inc. Adaptive immunity B and T lymphocytes produce a humoral and a cell-mediated immune response humoral immune response, antibodies help neutralize or eliminate toxins and pathogens in the blood and lymph cell-mediated immune response specialized T cells destroy infected host cells

34 © 2014 Pearson Education, Inc. Cytotoxic T Cells: Cytotoxic T cells recognize foreign proteins produced by infected cells and trigger apoptosis

35 © 2014 Pearson Education, Inc. Figure 35.14-1 Antigen fragment Class I MHC molecule Accessory protein Antigen receptor Cytotoxic T cell Infected cell 1

36 © 2014 Pearson Education, Inc. Figure 35.14-2 Antigen fragment Class I MHC molecule Accessory protein Antigen receptor Cytotoxic T cell Infected cell 1 Pore 2 Perforin Granzymes

37 © 2014 Pearson Education, Inc. Figure 35.14-3 Antigen fragment Class I MHC molecule Accessory protein Antigen receptor Cytotoxic T cell Infected cell 1 Pore 2 Perforin Granzymes Released cytotoxic T cell Dying infected cell 3

38 © 2014 Pearson Education, Inc. B Cells and Antibodies: A Response to Extracellular Pathogens humoral response - characterized by secretion of antibodies by B cells

39 © 2014 Pearson Education, Inc. Figure 35.15-1 Helper T cell Antigen fragments Pathogen CD4 Antigen- presenting cell Antigen receptor 1 MHC

40 © 2014 Pearson Education, Inc. Figure 35.15-2 Helper T cell Antigen fragments Pathogen CD4 Antigen- presenting cell Antigen receptor MHC B cell Cytokines Activated helper T cell 2 1

41 © 2014 Pearson Education, Inc. Figure 35.15-3 Helper T cell Antigen fragments Pathogen CD4 Antigen- presenting cell Antigen receptor MHC B cell Cytokines Activated helper T cell 2 1 3 Plasma cells Secreted antibodies Memory B cells

42 © 2014 Pearson Education, Inc. Antibodies... –…mark pathogens for destruction –…prevent infection by binding to virus –…bind to toxins.

43 © 2014 Pearson Education, Inc. Figure 35.16a B cell Helper T cell Antigen- presenting cell Engulfed by Antigen (1st exposure) Humoral (antibody-mediated) immune response Cell-mediated immune response Key Stimulates Gives rise to Cytotoxic T cell

44 © 2014 Pearson Education, Inc. Figure 35.16b B cell Helper T cell Humoral (antibody-mediated) immune response Cell-mediated immune response Cytotoxic T cell Key Stimulates Gives rise to Memory helper T cell Memory cytotoxic T cells Memory B cells Antigen (2nd exposure) Active cytotoxic T cells Defend against intracellular pathogens and cancer Defend against extracellular pathogens Plasma cells Secreted antibodies

45 © 2014 Pearson Education, Inc. Immunization Active immunization - –Antigen-containing material is injected –long-lasting immunity Passive – –antibody is injected –Protection is short lived

46 © 2014 Pearson Education, Inc. Fig. 39-21a, p.694Vaccines

47 © 2014 Pearson Education, Inc. Allergies Immune reaction to a harmless substance

48 © 2014 Pearson Education, Inc. Fig. 39-22a, p.694

49 © 2014 Pearson Education, Inc. Fig. 39-22b, p.694


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