Fichas
Immunology
Fichas del conjunto (114)
- 1What is Immunity?Body defenses that protect against disease
- 2What are some examples of soluble factors in innate immunity?Molecules causing low Ph in tears, saliva
enzymes that digest bacterial cell walls
Proteins coat bacterial to help destroy them (defensins, lysozymes) - 3What cells are involved in innate immunity?Macrophages
Neutrophils
Natural Killer Cells - 4What is the major innate defense mechanism?inflammation
- 5What is inflammation?A focused response: results in increased blood flow, accumulation of cells to area of tissue damage (such as microbial invasion).
- 6What are the characteristics of innate immunity?-No memory
-always ready
-responds immediately
-necessary, but not enough to protect from all invadors - 7What are the characteristics of Active Immunity?-Memory for specific invaders
-destroys them
-takes time to generate a response - 8Examples of foreign invaders.microbes; allergens; tissue graft from non-identical twin
- 9What do lymphocytes do?recognize specific molecules of specific foreign invaders
- 10What are antigens?molecules of the foreign invaders that are recognized by and stimulate the generation of lymphocytes with specificity
- 11How does the body encounter an antigen?Natural exposure to antigen: infection; allergen
Vaccines: We inject an antigen - 12What are the two types of acquired immunity?Humoral Immunity
Cell Mediated Immunity (CMI) - 13What is humoral immunity?-B-lymphocytes make an antibody
-Antibody targets invaders that are outside of cells
-targets EXTRACELLULAR bacteria; viruses before they get into cells, etc. - 14What is cell mediated immunity?-T-lymphocytes are the main players in CMI
-CMI targets cells that are infected with INTRACELLULAR pathogens - 15What is passive immunity?Acquired immunity from one animal (antibody usually) that is naturally or artificially given to another animal. The animal that receives it, acquired it passively.
- 16What are the two rabies Post-Exposure Prophylaxis?HDCV (Human diploid cell vaccine)
PCEC (Purified chick embryo cell vaccine) - 17What would you do to prevent rabies if never vaccinated?-wound clean
-HRIG (give antibody)* … IM injection
-Vaccinations: 4… days 0, 3, 7, 14
(passive immunity) - 18Why would a veterinarian need to understand the immune system?-Exposure to pathogens a certainty
-help patients combat disease or prevent disease by promoting an immune response
-Immunology the basis of many diagnostic tests and treatments - 19What is the difference between monocytes and macrophages?Monocytes if in the blood; called
macrophages when in tissues - 20What is an example of a Polymorphonuclear cell?granulocyte (neutrophil)
- 21WHat are natural killer cells?-can kill other cells: virally infected cells and tumor cells
-provide rapid response to target cells - 22How are NK cells different than Cytotoxic T-lymphocytes (CTLs)?NK cells do not recognize antigen, but rather recognize infected cells/tumor cells by other mechanisms
Takes time for CTLs to recognize and respond to target cells. - 23What do enzymes do?cause oxidative damage to membranes
- 24What are defensins?Anti-bacterial peptides
- 25What are interferons?CYTOKINES that can interfere with viral replication. Produced by phagocytes and other cells.
- 26What are cytokines?Small proteins that mediate cellular interactions and regulate cell growth and secretion. Thus, they regulate many aspects of the immune system
- 27What are complement proteins?A group of serum and cell-surface proteins that can be activated by both innate and acquired immune mechanisms (will cover this later) and result in a variety of biological events
- 28What is chemotaxis?chemical gradient to attract inflammatory cells (neutrophils, eosinophils, macrophages, etc.
- 29What are opsonins?Complement Proteins
AND OTHER PROTEINS…such as antibody… which coat microbes and help with phagocytosis by other cells - 30Which 2 leukocytes in blood are the primary phagocytes?Neutrophil + Monocyte
- 31What do neutrophils do-Myeloperoxidase (respiratory burst)
-Lysozyme (attacks carbohydrates in cell wall of gram+ bacteria
-Neutral and Acid hydrolases: Degrade bacteria - 32What is Polymorphonuclear leukocytes (PMNs)?First and Major phagocyte to respond to infections
- 33What is neutrophilia?-Above normal #s in blood
-stress, corticoids, etc. can
cause MP to move to CP… neutrophilia - 34What percentage of blood leukocytes do neutrophils constitute?Carnivores:60-75%
Horse: 50%
Ruminant: 20-30% - 35WHat happens to neutrophils during bacterial infection?there may be 10 X increase in numbers in circulation as they are released from the marrow
- 36What regarding neutrophils is found in bone marrow?proliferation pool, maturation pool, storage pool
- 37What is the life span of a neutrophil?6-10 hours
phagocytosis leads to death of the cell
Incapable of sustained killing - 38What allows neutrophils to attach to endothelium?Surface protein molecules (adhesion proteins)
- 39What are Surface protein molecules (adhesion proteins)?-example of integrins
-Involved in process of neutrophil migration into tissues - 40What are integrins?-Leukocyte adhesion molecule
-cell-surface protein molecules that promote adherence of the cell to various things
-Some integrins on neutrophils bind inflamed endothelial cells to allow the neutrophil to exit the vascular system and enter the tissue - 41What are chemokines?Chemotactic cytokines that are attractants for specific cells… help mediate inflammation
- 42What are the 4 steps of phagocytosis?-chemotaxis
-adherence
-ingestion
-destruction - 43What is vacoule called after ingestion?phagosome
- 44What is Oxygen-dependent killing within phagosome?Respiratory burst (RB): Phagocytic cells need O2 to kill by this mechanism
- 45How does Oxygen-independent killing in phagolysosome work?-Low pH: acidic; Toxic to most microbes
-Lysosomal enzymes (Proteases, DNAses, RNAses) are dumped into phagosomes during phagolysosome fusion and destroy bacterial cell walls
-can cause damage to host cells and tissues when cell ruptures - 46What are some pathogens that are resistant to lysosomal contents or that inhibit phagolysosomal fusion can survive in macrophages?-Mycobacterium bovis (cattle and humans)
-Rhodococcus equi (Disease in foals)
-Brucella abortus
-Listeria monocytogenes
-Salmonella typhimurium - 47Why are the number of neutrophils and monocytes increased in the blood, But are not present in the lesions??
- 48Why would a deficiency in leukocyte adhesion result in these lesions??
- 49What is the function of eosinophils?-Phagocytosis and killing of parasites
-Less efficient than PMNs and Macs (MØ) - 50What are the characteristics of basophils?-Minor population of cells in terms of numbers
-Granules contain vasoactive amines (histamine and serotonin)
-Promote inflammation and Immune responses
-Involved in allergic responses - 51What is the lifespan of monocytes/macrophages?-Long life span and maintain sustained phagocytosis*
-Macs down-regulated by steroids and prostaglandins
-The half-life of blood monocytes is about 1 day, whereas the life span of tissue macrophages is several months or years - 52What receptors are found on the surface of macrophages/monocytes? (same as neutrophils(-For Fc region of antibody
-For Complement proteins
-For Integrins (they also express integrins)
-For Cytokines (MØ also make cytokines*)
-Receptors that recognize LPS and other common molecules found on the surface of bacteria and other microbes - 53What is the function of macrophages/monocytes?-Sustained phagocytosis
-Oxydative + nonoxidative mechanisms
-Stimulated (activated) by products of the immune response and by dead cells such as neutrophils …Thus, often follow neutrophils into inflammatory site to clean up - 54What are interleukins?cytokines that act as growth and differentiation factors for cells of the immune system
- 55How are macrophages involved in wound healing?MØ release proteinase to breaks down collagen
MØ produce growth factors to promote new blood vessels (angiogenic) - 56What is the important function of macrophages?MØ are also Antigen Presenting Cells (APCs). They trap, process and present antigen to lymphocytes
- 57How do macrophages (and neutrophils) recgonize microbes?All macrophages have identical receptors* for recognizing microbes. These receptors allow the phagocytes to recognize groups of pathogens (i.e. Gram-negative, Gram+ bacteria, viral RNA).
*may not always be expressing all of them… need signals to express various receptors - 58What is PAMP?-Pathogen- Associated Membrane patterns
-Recognize microbial molecules that are common among microbes
- PAMP are often molecules essential for survival of the microbe and thus do not mutate or change expression - 59What are TLRs (Toll-like Receptors)?-One group (the most important group) of these Pattern Recognition Receptors (PRRs) are homologous in protein structure to the Drosophila (fruit fly) protein named “Toll”. Thus, are call Toll-like receptors (TLR).
- at least 10 different TLRs that have been identified.
-TLR are also expressed on several other cell types: mast cells, dendritic cells, eosinophils, neutrophils
-Thus, TLR are a type of PRR on phagocytic cells that recognize PAMP on microbes - 60What does the interaction between the TLR and the PAMP allows for?microbial recognition followed by engulfing and killing the microbe
- 61What does the interactions between TLR and PAMP initiate?signals that activate genes in the phagocytic cell that result in the production of cytokines. These cytokines in turn help to activate inflammation and aspects of the Adaptive Immune system as well
- 62What is anti-sera to an organism?serum containing Antibody to the organism
- 63What does serum contain?a ‘FACTOR’ capable of killing bacteria
-heat stable component(antibody)
-Heat labile component (comp protein) - 64What can complement proteins do?-Some can complement the activity of antibody
-Some can lyse cells without antibody being present - 65What are complement components?-Collection of over 20 proteins synthesized by hepatocytes and macrophages
-Comprise up to 10% of the globulin fraction of serum
-Exist as pro-enzymes or zymogens which are inactive enzymes until proteolytic cleavage which removes an inhibitory fragment and exposes the active site
-Designated by letters and numbers - 66What are the functions of complement proteins?-Antibody and non-antibody-mediated lysis of cells, bacteria, viruses, parasites
-Facilitate phagocytosis via opsonization
-Induce inflammation in tissues
chemotaxis of neutrophils,
increase vascular permeability,
smooth muscle contraction
-Promote Mast cell degranulation
-Clear immune complexes (antigen bound to antibody) from circulation and deposits them in spleen and liver - 67How does the complement assist the antibody?-With opsonization (Opsonizing antibody
facilitates phagocytosis)
-With lysis of cells (complement binds Ab that is already bound to the cell…causing lysis of cell) - 68What is the complement system?-Proteins in the blood plasma primarily
-No cells in the Complement System
-With an infection, the system of molecules is activated leading to a sequence of events that ultimately targets the surface of pathogens that help to destroy the pathogen and eliminate the infection - 69How is the Complement System activated?Alternate (natural) pathway-Activated without the help of antibody
- 70What are lectins?proteins that bind carbohydrates
- 71What is the lectin pathway?Does not depend on antibody
Mannose-binding lectin (MBL), an acute phase protein binds to mannose residues on glycoproteins on surfaces of microorganisms - 72What is the Classical Pathway?-By a specific immune response when Antibody (IgG or IgM) binds to Ag at the surface of a pathogen (or as complexes). The Fc region of the Ab that is bound to the pathogen (via its Fab variable part) can activate complement protein (C1)
-IgM much more efficient at activating C’ system – several closely spaced C’ binding sites
-Two IgG molecules have to be close together to activate C’ - 73What is complement assisting antibody?Complement binds antibody that is already bound to a cell and this causes lysis of the cell
- 74What happens when complement cascade is activated?At some point in the cascade there are steps in which the proteolysis (cleaving of the protein) of a complement protein leads to a small protein and a peptide being generated.
-Small protein remains bound to the complex at the surface of the pathogen.
-The peptide diffuses away and can produce other consequences.
Ex: Chemotaxis of neutrophils - 75What is Membrane Attack Complex (MAC) ?when cascade continues and at some point a final complex forms at the pathogen surface that causes cell lysis
- 76How can bacteria become resistant to complement system?Capsule prevents MAC insertion (Streptococcus)
Capsule prevents C3b deposition (Streptococcus)
Some bacteria possess elastase that inactivates some complement components - 77How can viruses become resistant to complement system?Some viruses interrupt complement cascade due to proteins that mimic regulatory proteins
- 78How can tumor cells become resistant to complement system?Some tumor cells can endocytose MAC then seal up the membrane
- 79Both C3a and C5a have anaphylatoxin activity, what does this trigger?-degranulation of mast cells
-increasing vascular permeability
-smooth muscle contraction. - 80What is an antigen?a substance capable, under appropriate conditions, of inducing a SPECIFIC immune response
-Is capable of interacting with the products of that immune response - 81What can an antigen interact with?Antibody
The T-cell receptor (TCR)
The B-cell receptor (BCR)
MHC molecules - 82What is the only way a T-cell can interact with an antigen?is if the antigen presenting cell presents an antigen to the T-cell receptor
- 83What is antigenicity?ability of an antigen to bind with immune components (antibodies; B-lymphocytes via the BCR; T-lymphocytes via the TCR)
- 84What is immunogenicity?ability of antigen to induce immune response
- 85What is a property of a good immunogen?Needs to be >1000 Daltons (1kDa) to be immunogenic
- 86What are some poor immunogens?-Simple repeating units are poor immunogens: polymers, like carbohydrates, plastics
-Lipids and nucleic acids, in general, are poor immunogens - 87What are some good immunogens?Proteins and glycoproteins are complex molecules and usually good immunogens
- 88How do nucleic acids differ in mammals?Mammalian nucleic acids poorly immunogenic in mammals (simple molecules, readily degraded). BUT prokaryotic nucleic acids can stimulate a potent immune response in a mammal (CpG motifs of bacterial DNA).
- 89What can protect bacteria from an immune response?a polymer capsular coating
-ex:Bacillus anthracis - 90What can be done to proteins that are easily degraded so that they are immunogenic?can first be “fixed” with heat or formaldehyde which slows down degradation and improves immunogenicity. Fixing will also inactivate a toxin that one might want to use as an immunogen
- 91What is an epitope?That portion of the immunogenic molecule which actually binds with antibody or the TCR or the BCR. The TCR, BCR and Antibody do not recognize the entire immunogenic molecule. Instead, they only recognize a discrete site
- 92How many epitopes does a single immunogenic molecule have?A single immunogenic molecule may have several different epitopes. Each different epitope will be recognized by different antibody, BCR and/or TCR.
- 93What happens to protein epitopes if they are degraded?the immunogenicity may be lost
- 94What happens when Identical or similar epitopes are found on apparently unrelated molecules?antibodies directed against one antigen may react unexpectedly with an unrelated antigen
- 95What are natural antibodies?Antibodies against foreign antigens without any known previous infection, vaccination, other foreign antigen exposure or immunization
- 96Not all antigens are immunogenic but...but all immunogens are antigens
- 97What do haptens do?Allow molecules that are antigenic, but not immunogenic to bind to a carrier protein to create an immune response
- 98What are extracellular pathogens?Most bacteria and most parasites… (but not all). These microbes replicate outside of the host cell.
- 99What are intracellular pathogens?Viruses and some bacteria. Please note that viruses and obligate intracellular bacteria will exist outside a host cell prior to infecting it. But they need to be inside the host cell in order to replicate.
- 100What are examples of some bacteria that can replicate inside a host cell?Mycobacterium sp.
Rhodococcus equi
Listeria monocytogenes
Brucella abortus - 101What is an exogenous antigen?antigens made outside the cell
- 102What is an endogenous antigen?antigen made within the cell
- 103Where do viral contents go?go into the cytosol (not into phagosomes).. And replicate and thus make endogenous antigen
- 104What can kill virus-infected host cells ?immune cells (NK and CTLs)
- 105What are cell surface antigens?molecules expressed on the surface of normal cells that in another animal could stimulate an immune response are also referred to as antigens
- 106What are Major Histocompatibility Complex molecules (MHC)?Protein molecules expressed on the surface of most nucleated cells
- 107Whats the difference between MHC-1 and MHC-2?MHC-I molecules can be induced to be expressed on most nucleated cells.
MHC-II molecules are only expressed on Antigen-Presenting Cells (APCs) - 108What are Cluster of Differentiation molecules?Surface molecules (antigens) on immune cells. Expression of these molecules on lymphocytes is used to define subsets of lymphocytes.
- 109How is CD4 expressed?expressed by a subset of T-lymphocytes that have “helper” function
- 110How is CD8 expressed?expressed on a subset of T-lymphocytes that “kill” abnormal cells.
- 111How is CD25 expressed?molecule expressed on a number of different types of cells and its function is to bind IL-2. Thus, any cell expressing CD25 can respond to IL-2. …
also called ‘Interleukin-2 Receptor’ (IL-2R) - 112What is essential for the adaptive immune response?Antigen
Antigen Presenting Cells (APCs)
MHC molecules
B- and T-lymphocytes - 113WHat is the humoral immune response?Antigen presenting cells that engulf antigen (exogenous)can process and present this exogenous antigen via MHC-II molecules to T helper lymphocytes… T-helper cells can stimulate B cells to make antibody.
- 114What is the cell mediated response?Infected, nucleated cell can process and present endogenous antigen via MHC-I molecules to Cytotoxic T lymphocytes.