I C MIcro451 Immunology Prof Nagwa Mohamed Aref Molecular Virologist amp Immunology 2 The Second Line of Defense Inflammation Phagocytosis Interferon Complement The Inflammatory Response A Complex Concert of Reactions to Injury ID: 933360
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Slide1
Host Defenses Overview and Nonspecific Defenses I- C
MIcro451 Immunology
Prof.
Nagwa
Mohamed
Aref
(Molecular Virologist & Immunology)
Slide22. The Second Line of DefenseInflammationPhagocytosisInterferonComplement
Slide3The Inflammatory Response: A Complex Concert of Reactions to InjuryReaction to any traumatic event in the tissuesClassic signs and symptomsRubor (redness)Calor (warmth)
Tumor (swelling)
Dolor (pain)
Fifth symptom has been added: loss of function
Slide4Figure 14.12
Slide5Stages of inflammationBlood vessels dilate in response to chemical mediators and cytokinesEdema swells tissues, helping prevent spread of infection
WBC’s, microbes, debris and fluid collect to form pus
Pyrogens may induce fever
Macrophages and neutrophils engage phagocytosis
5
Slide6Chief Functions of Inflammation Chief functions of inflammationMobilize and attract immune components to the site of the injurySet in motion mechanisms to repair tissue damage and localize and clear away harmful substancesDestroy microbes and block their further invasion
Slide7The Stages of InflammationFigure 14.13
Slide8Vascular Changes: Early Inflammatory EventsControlled by nervous stimulation, chemical mediators
, and
cytokines
released by blood cells, tissue cells, and platelets in the injured area
Vasoactive
mediators affect the endothelial cells and smooth muscle cells of blood vessels
Chemotactic
factors
(
chemokines
) affect white blood cells
Cause fever, stimulate lymphocytes, prevent virus spread, and cause allergic symptoms
Arterioles constricted at first but quickly
vasodilation
takes place
Slide9Edema: Leakage of Vascular Fluid into Tissues
Exudates: the fluid that escapes through gaps in the walls of
postcapillary
venules
Accumulation of exudates causes edema
Contains plasma proteins, blood cells, and cellular debris
May be clear (serous) or may contain red blood cells or
pus
Diapedesis
: how WBCs leave the blood vessels and into tissue spaces
Chemotaxis
: the tendency of WBCs to migrate in response to a specific chemical stimulus
Slide10Benefits of Edema and ChemotaxisDilutes toxic substancesFibrin clot can trap microbes and prevent further spreadingPhagocytosis occurs immediately
Slide11Slide12Fever: An Adjunct to InflammationAn abnormally elevated body temperatureFUO: fevers of unknown originInitiation of feverPyrogen sets the hypothalamic “thermostat” to a higher setting
Muscles increase heat production
Peripheral arterioles decrease heat loss through vasoconstriction
Pyrogens can be exogenous or endogenous
Slide13Benefits of FeverInhibits multiplication of temperature-sensitive microorganismsImpedes the nutrition of bacteria by reducing the availability of ironIncreases metabolism and stimulates immune reactions and naturally protective physiological processes
Slide14Phagocytosis: Cornerstone of Inflammation and Specific ImmunityGeneral activities of phagocytes
Survey the tissue compartments and discover microbes, particulate matter, and injured or dead cells
Ingest and eliminate these materials
Extract immunogenic information (antigens) from foreign matter
Three main types
Neutrophils
Monocytes
Macrophages
Slide15Activities of phagocytesTo survey tissue compartments & discover microbes, particulate matter & dead or injured cellsTo infest and eliminate these materials
To extract immunogenic information from foreign matter
15
Slide16Figure 14.15
Slide17Figure 14.16
Slide18Mechanisms of Phagocytic Recognition, Engulfment, and Killing
Figure 14.17
Slide19Late Reactions of InflammationLong-lived inflammation attracts a collection of monocytes, lymphocytes, and macrophages to the reaction site
Macrophages clear pus, cellular debris, dead
neutrophils
, and damaged tissue
B lymphocytes produce antibodies
T lymphocytes kill intruders directly
Late in the process the tissue is repaired or replaced by connective tissue (scar)
Slide20Interferon: Antiviral Cytokines and Immune StimulantsInterferon (IFN): involved against viruses, other microbes, in immune regulation and intercommunication
Three major types
Interferon alpha
Interferon beta
Interferon gamma
All three classes produced in response to viruses, RNA, immune products, and various antigens
Bind to cell surfaces and induce changes in genetic expression
Can inhibit the expression of cancer genes and have tumor suppressor effects
Slide21Figure 14.18
Slide222210/09Mickey Dufilho
Slide23Complement: A Versatile Backup SystemConsists of 26 blood proteins that work in concert to destroy bacteria and viruses
Complement proteins are activated by cleavage (cascade reaction)
Pathways
Classical – activated by the presence of antibody bound to microorganism
Lectin
pathway – nonspecific reaction of a host serum protein that binds
mannan
Alternative – begins when complement proteins bind to normal cell wall and surface components of microorganisms
10/09
Mickey Dufilho
23
Slide24Stages in the Complement CascadeInitiationAmplification and cascadePolymerization
Membrane attack
10/09
Mickey Dufilho
24
Slide252510/09Mickey Dufilho
Slide2610/09Mickey Dufilho26
Slide2710/09Mickey Dufilho27
Figure 14.20(b, c, d)
Slide28Slide2929
Complement: Classical Pathway
Slide30Specific immunitiesB and T lymphocytesSpecificity and memory30
Slide3131