Copyright © 2010 Pearson Education, Inc. INNATE IMMUNITY – NONSPECIFIC DEFENSES OF THE HOST CHAPTER 16

Copyright © 2010 Pearson Education, Inc. The Concept of Immunity  Susceptibility: Lack of resistance to a disease  Immunity: Ability to ward off disease  Innate immunity: Defenses against any pathogen  Adaptive immunity: Immunity, resistance to a specific pathogen

Copyright © 2010 Pearson Education, Inc. The Concept of Immunity  Host Toll-like receptors (TLRs) attach to  Pathogen-associated molecular patterns (PAMPs)  TLRs induce cytokines that regulate the intensity and duration of immune responses

Copyright © 2010 Pearson Education, Inc. Physical Factors  Skin  Epidermis consists of tightly packed cells with  Keratin, a protective protein Figure 16.2

Copyright © 2010 Pearson Education, Inc. Physical Factors  Mucous membranes  Mucus: Traps microbes  Ciliary escalator: Microbes trapped in mucus are transported away from the lungs

Copyright © 2010 Pearson Education, Inc. Ciliary Escalator Figure 24.7

Copyright © 2010 Pearson Education, Inc. Ciliary Escalator Figure 16.4

Copyright © 2010 Pearson Education, Inc. Physical Factors  Lacrimal apparatus: Washes eye  Saliva: Washes microbes off  Urine: Flows out  Vaginal secretions: Flow out

Copyright © 2010 Pearson Education, Inc. Lacrimal Apparatus Figure 16.3

Copyright © 2010 Pearson Education, Inc. Q&A During one year, nosocomial infections occurred in 74 patients in one hospital. All 74 patients were intubated and mechanically ventilated. The infections were caused by Burkholderia cepacia transmitted in nonsterile mouthwash.

Copyright © 2010 Pearson Education, Inc. Q&A Why did these patients develop infections while others who used the mouthwash were not infected?

Copyright © 2010 Pearson Education, Inc. Chemical Factors  Fungistatic fatty acid in sebum  Low pH (3–5) of skin  Lysozyme in perspiration, tears, saliva, and urine  Low pH (1.2–3.0) of gastric juice  Low pH (3–5) of vaginal secretions

Copyright © 2010 Pearson Education, Inc. Normal Microbiota and Innate Immunity  Microbial antagonism/competitive exclusion: Normal microbiota compete with pathogens or alter the environment  Commensal microbiota: One organism (microbe) benefits and the other (host) is unharmed  May be opportunistic pathogens

Copyright © 2010 Pearson Education, Inc. Red Blood CellsTransport O 2 and CO 2 White Blood Cells: NeutrophilsPhagocytosis BasophilesHistamine EosinophilsKill parasites Formed Elements in Blood

Copyright © 2010 Pearson Education, Inc. Formed Elements in Blood MonocytesPhagocytosis Dendritic cellsPhagocytosis Natural killer cellsDestroy target cells

Copyright © 2010 Pearson Education, Inc. Formed Elements in Blood T cellsCell-mediated immunity B cellsProduce antibodies PlateletsBlood clotting

Copyright © 2010 Pearson Education, Inc.  Percentage of each type of white cell in a sample of 100 white blood cells Neutrophils60–70% Basophils0.5–1% Eosinophils2–4% Monocytes3–8% Lymphocytes20–25% Differential White Cell Count

Copyright © 2010 Pearson Education, Inc. Components of Lymphatic System Figure 16.5a

Copyright © 2010 Pearson Education, Inc. The Lymphatic System Figure 16.5b–c

Copyright © 2010 Pearson Education, Inc. Phagocytosis  Phago: From Greek, meaning eat  Cyte: From Greek, meaning cell  Ingestion of microbes or particles by a cell, performed by phagocytes Figure 16.6 Phagocytic cells: Neutrophils, Fixed macrophages, Wandering macrophages

Copyright © 2010 Pearson Education, Inc. Figure 16.7 Phagocytosis

Copyright © 2010 Pearson Education, Inc. Inhibit adherence: M protein, capsules Streptococcus pyogenes, S. pneumoniae Kill phagocytes: LeukocidinsStaphylococcus aureus Lyse phagocytes: Membrane attack complex Listeria monocytogenes Escape phagosomeShigella, Rickettsia Prevent phagosome-lysosome fusion HIV, Mycobacterium tuberculosis Survive in phagolysosomeCoxiella burnettii Microbial Evasion of Phagocytosis

Copyright © 2010 Pearson Education, Inc. Inflammation  Acute-phase proteins activated (complement, cytokine, and kinins)  Vasodilation (histamine, kinins, prostaglandins, and leukotrienes)  Redness  Swelling (edema)  Pain  Heat

Copyright © 2010 Pearson Education, Inc. HistamineVasodilation, increased permeability of blood vessels KininsVasodilation, increased permeability of blood vessels ProstaglandinsIntensity histamine and kinin effect LeukotrienesIncreased permeability of blood vessels, phagocytic attachment Chemicals Released by Damaged Cells

Copyright © 2010 Pearson Education, Inc. The Process of Inflammation Figure 16.8a, b

Copyright © 2010 Pearson Education, Inc. Phagocyte Migration and Phagocytosis Figure 16.8c [Insert Animation Inflammation: Overview, Steps.]

Copyright © 2010 Pearson Education, Inc. Tissue Repair Figure 16.8d

Copyright © 2010 Pearson Education, Inc. Fever  Abnormally high body temperature  Hypothalamus normally set at 37°C  Gram-negative endotoxin cause phagocytes to release interleukin–1 (IL–1)  Hypothalamus releases prostaglandins that reset the hypothalamus to a high temperature  Body increases rate of metabolism and shivering which raise temperature  Vasodilation and sweating: Body temperature falls (crisis)

Copyright © 2010 Pearson Education, Inc. Fever  Advantages  Increases transferrins  Increases IL–1 activity  Produces Interferon  Disadvantages  Tachycardia  Acidosis  Dehydration  44–46°C fatal

Copyright © 2010 Pearson Education, Inc. The Complement System  Serum proteins activated in a cascade  Activated by  Antigen-antibody reaction  Proteins C3, B, D, P and a pathogen  C3b causes opsonization  C3a + C5a cause inflammation  C5b + C6 + C7 + C8 + C9 cause cell lysis

Copyright © 2010 Pearson Education, Inc. The Complement System Figure 16.9

Copyright © 2010 Pearson Education, Inc. Effects of Complement Activation  Opsonization or immune adherence: Enhanced phagocytosis  Membrane attack complex: Cytolysis  Attract phagocytes Figure 16.10

Copyright © 2010 Pearson Education, Inc. Inflammation Stimulated by Complement Figure 16.11

Copyright © 2010 Pearson Education, Inc. Classical Pathway of Complement Activation Figure 16.12

Copyright © 2010 Pearson Education, Inc. Alternative Pathway of Complement Activation Figure 16.13

Copyright © 2010 Pearson Education, Inc. Lectin Pathway of Complement Activation Figure 16.14

Copyright © 2010 Pearson Education, Inc. Some Bacteria Evade Complement  Capsules prevent C activation  Surface lipid-carbohydrates prevent membrane attack complex (MAC) formation  Enzymatic digestion of C5a

Copyright © 2010 Pearson Education, Inc. Interferons (IFNs)  IFN-  and IFN-  : Cause cells to produce antiviral proteins that inhibit viral replication  Gamma IFN: Causes neutrophils and macrophages to phagocytize bacteria

Copyright © 2010 Pearson Education, Inc. Antiviral Actions of Interferons (IFNs) Figure 16.15

Copyright © 2010 Pearson Education, Inc. Innate Immunity  Transferrins  Bind serum iron  Antimicrobial peptides  Lyse bacterial cells