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Peyer's patches
are covered by an epithelial layer containing specialized cells called M cells which have characteristic membrane ruffles TERM 2
Innate Immunity
DEFINITION 2 Initial protection from infection Physical Barriers Humoral Barriers Myeloid cells NK cells TERM 3
Barriers -Skin
DEFINITION 3 mechanical - epithelial cells joined by tight junction - longitudinal flow of air or fluidchemical - fatty acids - B- defensins, lamellar bodies, cathelidinmicrobiological - normal microbiota TERM 4
barriers - Gut
DEFINITION 4 Mechanical - epithelial cells joined by tight junctions - longitudinal flow of air or fluidchemical - low pH and enzymes (pepsin) - a-defenisins (cryptdins), Reg!!! (lecticidins) and Cathelicidinmicrobiological - normal microbiota TERM 5
barriers - lungs
DEFINITION 5 mechanical - epithelial cells joined by tight junctions - movement of mucus by ciliachemical - pulmonary surfactant
- a-defensins, cathelicidinmicrobiological - normal microbiota
barries -eyes/nose/oral
mechanical- epthial cells joined by tight junctions - tears, nasal ciliachemical - enzymes in tears and saliva (lysozyme) - histatins, B-defensinsmicrobiological - normal microbiota TERM 7
Innate immunity - Humoral Barriers
DEFINITION 7 Complement Lysozyme and Defensins Lactoferrin Interferons Inflammatory cytokines TERM 8
Innate immunity -Complement
DEFINITION 8 Definition : series of heatlabile serum proteinsSite : serum and all tissue fluids except urine and CSFSynthesis : in liver appear in fetal circulation during 1st 13 WFunc&on : Responsible for certain aspects of immune response and inflammatory responseActivation : antigenantibody complex or endotoxin, capsuleseries of proteins activated sequentiallyInactivation: inhibitors in plasma (short lived)Biological effects: either beneficial or harmful to host TERM 9
Classic And Alterenative pathways
DEFINITION 9 Classic Pathway Specific acquired immunity Initiated by antibody interaction of all components Properdin system not involved Alternative Pathway non-specific innate immunity Bacterial endotoxin, capsule C1, C4, C2 are by-passed Properdin system is involved TERM 10
Innate Immunity - Lysozyme and defensins
DEFINITION 10 electrostatic attraction and the transmembrane electric field bring the defensin into the lipid bilayer.defensin peptides form a pore
IL-
local effectslymphocyte activationincreased antibody productionSystemic effectsFeverinduces acute phaseprotein production TERM 17
CXCL
DEFINITION 17 local effectschemotactic factor recruits neutrophils, basophils and T cells to site of infection TERM 18
IL-
DEFINITION 18 local effectsactivates NK cellsinduces the differentiation of CD4 T cells into TH1 cells TERM 19
Myeloid cells
DEFINITION 19 MacrophageDendritic cellneutrophilEosinophilBasophilMast cell TERM 20
Macrophage
DEFINITION 20 phagocytosis and activation of bactericidal mechanismsantigen presentation
Dendritic cell
Antigen uptake in peripheral sitesantigen presentationform the bridge between innate and adaptive responsesare phagocytic in the immature phase. after maturing they present pathogen antigens to T lymphcytes, thus activating t lymphocytes and innitiating adaptive immune response. TERM 22
Neutrophil
DEFINITION 22 Phagocytosis and activation of bactericidal mechanisms TERM 23
eosinophil
DEFINITION 23 killing of antibody-coated parasites TERM 24
basophil
DEFINITION 24 promotion of allergic responses and augmentation of anti- parasitic immunity TERM 25
mast cell
DEFINITION 25 release of granules containing histamine and active agents
BCR vs TCR
BCR - schematic structure of an antibody moleculeTCR - schematic structure of the T-cell receptor TERM 32
TCR anitgen recognition
DEFINITION 32 the epitopes recognized by T-cell receptors are often burried the antigen must first be broken down into peptide fragments the epitope peptide binds to a self molecule, an MHC molecule The T-cell receptor binds to a complex of MHC molecule and epitope peptide TERM 33
epitope
DEFINITION 33 An epitope, also known as antigenic determinant, is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. TERM 34
Lymphocyte activation
DEFINITION 34 antigen-receptor binding and co-stimulation of T-cell by dendritic cell --> proliferation and differentiation of T cell to acquire effector function antigen-receptor binding and activation of B cell by T cell --
proliferation and differentiation of B cell to acquire effector function TERM 35
Acquired Immunity - Professional antigen
presenting cells
DEFINITION 35 dendritic cellmacrophageB lymphocyte
The effector mechanisms of adaptive
immunity
Antibodies protect against extracellular pathogens and their toxic productsT cells orchestrate cell-mediated immunity and regulate B-cellresponses to most antigensCD4 and CD8 T cells recognize peptides bound to two differentclasses of MHC moleculesInherited and acquired defects in the immune system result inincreased susceptibility to infectionUnderstanding adaptive immune responses is important for the controlof allergies, autoimmune disease, and the rejection of transplantedorgansVaccination is the most effective means of controlling infectiousdiseases TERM 37
adaptive immune response
DEFINITION 37 production of antibodies against a particular pathogen.developed during the lifetime of the individual as an adaption to infection with that pathogenoften results in immunological memory TERM 38
innate immune response
DEFINITION 38 always immediately available to combat a wide range ofpathogensbut does not lead to lasting immunity and is not specific for any individual pathogen.macropages are the front line component of innate immune response. TERM 39
antigen
DEFINITION 39 any substance taht can be recognized and responded by the adaptive immune system TERM 40
four task to protect against disease
DEFINITION 40 Immunolgical recognition - detection of the infection. carried out by the wbc's of the innate system and the lymphocytes of the adaptive system. immune effector function - contain and if possible eliminate. immune regulation - self regulate. failure to do so may lead to allergy or autoimmune disease. immunological memory -
T cell receptor
after the T-cell has been activated by its first encounter with antigen, it proliferates and differentiates into one of several effector T-lymphocytes.Cytoxic T cellsHelper T cellsRegulatory T cells TERM 47
Lymphocytes
DEFINITION 47 mature in the bone marrow or the thymus and then congregate in lymphoid tissues throughout the body.Central or primary lymphoid organs - where lymphcytes are genrated. bone marrow and thymus.peripheral or secondary organs - where mature naive lymphocytes are maintained and adaptive responses are initiated. lymph nodes, spleen, mucosal lymph tissue of gut, nasal and respiratory tract, urogenital tract. TERM 48
infectious agents activate the innate immune
system and induce an inflammatory response
DEFINITION 48 macrophages engulf and degrade the bacterium internally and secrete cytokines and chemokines.cytokines - a protein that affects the behavior of nearby cells.chemokines - proteins that act as a chemoattractant. and attract cells such as nuetrophils and monocytes out of the blood stream and into the infected tissue..the cytokines and chemokines released initiate the process known as inflammation. TERM 49
Complement
DEFINITION 49 a group of plasma proteins.can also trigger an inflamatory resppnseactivation of the complement system leads to a cascade that coats microbes which are then bound by complement receptors on macrophages and destroyed.cytokines and complement fragments also effect endothelium of blood vessels. cytokines cause circulating leukocytes to stick to endothial cells and migrate to site of infection. this migration is what accounts for pain. TERM 50
Pattern recognition receptors of the innate
immune system
DEFINITION 50 provide an initial discrimination between self and nonselfthe pathogen-recognition receptors of macrophages neutrophils and dendritic cells recognize simple molecules and regular patterns of molecular structure known as pathogen-associated molecular patterns PAMP, that are present on microorganisms.the receptors that recognize PAMPs are known as pattern recognition receptors PRR
Adaptive immune responses
are initiated by antigen and antigen presenting cells in secondary lymphoid tissues immature dendritic cells reside in peripheral tissues dendritic cells migrate via lymphatic vessels to regional lymph nodes mature dendritic cells activate naive T-cells in lymphoid organs such as lymph nodes. TERM 52
Lymphocytes activated by antigen
DEFINITION 52 give rise to clones of antigen specific effector cells that mediate adaptive immunity TERM 53
Clonal selection of lymphocytes
DEFINITION 53 the central principle of adaptive immunity TERM 54
The structure of the antibody molecule
DEFINITION 54 composed of two distinct regionsthe Constant region, which only has 4 or 5 distinguishable formsthe Variable region, can have an infinite number of amino acid sequences that allow antibodies to specifically to antigensthe variable region of the antibody determines the antigen binding specificity.there are two identical variable regions in an antibody and therefore two identical antigen-binding sites.the constant region determines the effector function of the antibody TERM 55
structure of the T-cell receptor
DEFINITION 55 composed of two chains of equal length called T-cell receptor alpha and beta chains, each of which spans the T-cell membraneeach chain has a variable and constant region, and the combination of the alpha and beta variable regions creats a single site for antigen binding.the T-cell receptor does not bind antigens directly, instead it recognizes fragments of antigens bound to surface of other cells.
Lymphocytes encounter and respond to
antigen
in the peripheral lymphoid organs TERM 62
Lymphocyte activation requires additional
signals
DEFINITION 62 For naive T-cells - an activated dendritic cell usually delivers these signalsFor naive B-cells - the second signal is delivered by an activated helper T-cell TERM 63
major types of pathogens confronting the
immune system
DEFINITION 63 extracellular bacteria, parasites, fungi intracellular bacteria, parasites viruses (intracellular) parasitic worms (extracellular) TERM 64
humoral immunity
DEFINITION 64 immunity mediated by antibodies TERM 65
Ways antibodies protect against pathogens
DEFINITION 65 bind the pathogen directly, blocking their access to cells that they might infect or destroy. known as neutralization Opsonization. The coating of pathogens to be phagocytosed Complement Activation. when an antibody binds to a bacterial surface, its constant regions provide a platform to activate the first protein of the complement system
cell mediated immune response
some pathogens, bacteria and all viruses replicate inside cells, where they cannot be detected by antibodies. the destruction of intracellular invades is by T-lymphocytes, which are responsible for the Cell mediated immune response of adaptive immunity. TERM 67
Cytotoxicity
DEFINITION 67 the most direct action of T-cells. Cytoxic T-cells are effector T-cells that act against cells infected with viruses. TERM 68
CD8 and CD
DEFINITION 68 From their end of development in the thymus, T-lymphocytes are composed of two main classes, one of which carries the cell surface protein called CD8 on its surface and the other bears a protein called CD4.Cytoxic T-cells carry CD8Helper T- cells carry CD44 main types of CD4 effector T-cells. Th1, Th2, Th17, Tfh. TERM 69
CD4 and CD8 T cells recognize peptides
bound to two different classes of MHC
molecules
DEFINITION 69 CD8 T-cells recognize peptides that are bound to MHC class 1CD T-cells recognize peptides bound to MHC class 2CD4 and CD8 are known as Co-receptorsMHC class 1 collect peptides derived from proteins synthesized in the cytosol and are thus able to display fragments of viral proteins.MHC class 2 are expressed predominantly by antigen-presenting cells (dendritic, macrophage, B-cells) and bind peptides derived from proteins in intracellular vesicles. TERM 70
cytotoxic CD8 T-cells recognize...
DEFINITION 70 antigen presented by MHC class 1 molecules and kill the cell
