XIII. Basics of Immunology

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XIII. Basics of Immunology

• Chapters 29, 30 and 32

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A. Overview of Immunity

• What are the 2 parts of the immune system?
• a. Innate
• 1) What are the 2 parts of the innate
  immunity?
• a) Barriers and some chemicals
• released by the barriers
• b) Phagocytes, complement, interferon,
• inflammations fever
• 2) When does it start?
• You are born with it

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• b. Adaptive immunity or Cell mediated or
  Specific immunity
• 1) Define this part?
• acquired ability to recognize destroy a
  pathogen or its products and is activated by
  exposure of the immune system to the pathogen
• 2) What are adaptive responses directed to?
• certain molecules on the pathogen

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Bauman, Robert W. Microbiology Text
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2. Cells Organs of the Immune System

• What do the following components of the blood and
  lymph do?
• 1) Erythrocytes Carry O2 from lungs to tissue
  some CO2 from tissue to lungs
• 2) Leukocytes
• a) monocytes
• develop into macrophages or dendritic cells
• b) eosinophils
• Involved in phagocytosis
• important in battling helminth infections

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• c) B lymphocytes
• precursors to plasma cells which produce
  antibodies
• d) T lympohcytes
• involved in cell killing activation of B
  lymphocytes other parts of the cell mediated
  immunity
• e) neutrophils-
• Phagocytic granulocytes they do phagocytosis
  can cause inflammation allergy-like symptoms

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• f) mast cells
• granulocytes that when they undergo
  degranulation they can cause inflammation and
  allergy-like symptoms
• 3) plasma
• whole blood when taken out of the body it
  quickly forms an insoluble clot this can trap
  cells
• 4) serum-
• has no cells or clotting proteins but does
  have other proteins like antibody proteins

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• b. What is the circulation of the blood?

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• c. What is the function of the Lymph system?
• to collect fluid that has left the circulatory
  system, filter it with lymph nodes and return it
  to the circulatory system through the thoracic
  lymph duct.

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• d. What are the primary organs of the lymph
  system?
• 1) bone marrow
• 2) thymus
• e. What are the secondary organs of the lymph
  system?
• 1) lymph nodes
• 2) spleen
• 3) Mucosal-associated lymphoid tissue (MALT)

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• f. myeloid cells
• 1) What 2 categories can they be divided into
  what is the function of each?
• a) monocytes
• become macrophages which are phagocytic cells
• b) granulocytes
• neutrophils phagocytosis
• others release granules resulting in
  inflammation and/or allergy like symptoms

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3. The Innate response after the physical
chemical barrier part of the innate immune system
has been breached

• What is the 1st cell type active in the
  inflammatory response what is its function?
• phagocyte
• function is to engulf and destroy pathogens
• some then function as antigen presenting cells
  (APC)
• b. What are APCs?
• Phagocytes that process and display peptide
  antigens from the invader

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• c. Steps in phagocytosis

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• d. Neutrophils
• 1) What is another name for them?
• polymorphonuclear leukocytes (PMNs)
• 2) Where are they predominantly found?
• the bloodstream and bone marrow
• 3) What would a high count in the blood
  indicate?
• active response to a current infection

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• e. Monocytes
• 1) What do monocytes become?
• macrophages
• 2) What is the difference between fixed
  macrophages and wandering macrophages?
• Fixed stay permanently in a location and are
  named for their location
• Alveolar macrophages lung
• microglia CNS
• Kupffer cells liver
• Wandering leave the blood via diapedesis and
  scavenge while traveling

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• 3. Macrophages and Dendritic cells also act as
  APCs. They both present the antigen to T cells
  which commences the adaptive immune response.

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Figure A is a neutrophil note the segmented
nucleus is a monocyte everything else
are RBC


Figure B is a circulating lymphocyte

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• f. How do the following bacteria inhibit
  phagocytes?
• 1) Staphylococcus aureus
• produces carotenoids that neutralize singlet
  oxygen used in
• phagolysosmes to kill bacteria
• 2) Mycobacterium tuberculosis
• uses its cell wall glycolipids to absorb
  OH-and O2-

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• g. How do the following chemicals or structures
  interfere with phagocytosis?
• 1) leukocidins
• phagocyte-killing proteins upon the death of
  the phagocyte the pathogen is released
• 2)capsules
• This structure prevents the adherence of the
  phagocyte
• 3) M protein
• alters the surface of the bacterial cell
  preventing phagocytosis

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• 4. Inflammation, Fever and Septic Shock
• a. What are the signs and symptoms of
  inflammation?
• 1) erythema (redness)- due to increased blood
  flow to the area
• 2) edema (swelling) due to leaky capillaries
• 3) pain- due to increase fluid equals increased
  pressure on nerve endings
• 4) heat- due to increased blood flow to the area

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• b. Who are the 1st cells to arrive at the site
  of invasion and what attracts them there?
• neutrophils
• interleukins and other soluble chemoattractants

Figure (a) is a neutrophil ingesting and killing
Neisseria gonorrhoeae
Figure (b) skin macrophage that has ingested
Leishmania
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• c. What do they do, what do they secrete and
  what do their secretions do?
• migrate to the damaged cells and ingest them
• They secrete chemokines like macrophage
  inflammatory proteins a and ß
• These chemicals recruit more macrophages to
  the site

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• d. What is the usual outcome of the inflammatory
  response?
• localizing of pathogen then destruction of
  pathogen
• e. What can an inflammatory response that
  spreads cells mediators throughout the system
  lead to?
• Septic shock
• What bacteria are the most common causes of
  this?
• Gram-negative enteric bacteria such as
  Salmonella or E. coli

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Signs Symptoms of Septic Shock

• Septic shock can affect any part of the body,
  including the heart, brain, kidneys, liver,
  intestines. Symptoms may include
• Cool, pale extremities
• High or very low temperature, chills
• Lightheadedness
• Low blood pressure, especially when standing
• Low urine output
• Palpitations
• Rapid heart rate
• Restlessness, agitation, lethargy, or confusion
• Shortness of breath

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5. Adaptive Immune Response

• f. What is the problem with wide vasodilation
  increased vascular permeability?
• Massive movement of fluids into the CNS drop in
  blood pressure and edema in the CNS system wide
• If the pathogen gets through the innate response
  and an APC activates a T-cell what are the 2
  parts of the cell-mediated response that are
  activated?
• 1) T-cytotoxic cells may be activated to
  directly attack destroy antigen bearing cells
• 2) T-helper cells are activated
• a) TH1secrete cytokines activate macrophages
• b) TH2 interact with B cells to stimulate Ab
  prod.

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• b. What is the broad based outcome of activating
  other T cells?
• cell mediated immunity inflammation, killing
  antigen destruction
• c. What is the broad based outcome of activating
  B cells?
• antigen specific, antibody-mediated immunity
  complement activation destruction
• d. What is immune memory and what does it allow
  our bodies to do?
• When T B cells are activated they divide to
  become active cells (T cells) or plasma cells
  (B cells) memory cells
• Active cells do their job, plasma cells produce
  antibodies and memory cells provide a faster
  response if the antigen comes back

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• 1) How do we take advantage of immune memory?
• vaccination
• e. What is tolerance and why is it important?
• The elimination of any adaptive immune response
  to self
• Important to prevent destruction of our cells
  due to our own immune system attacking them.

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B. Antigens Antigen Presentation

• Distinguish between antigens immunogens
• antigens substances that react with Ab or TCRs
• Immunogens substances that induce an immune
  response
• 2. What are the important intrinsic properties
  of immunogens?
• Molecular size- very small molecules called
  haptens cannot induce an immune response but can
  be bound by Ab but if attached to a larger
  protein they become immunogens pencillin is a
  hapten
• immunogens need to have a MW of 10,000 daltons
  or larger

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• b. Molecular complexity
• nonrepeating polymers and complex carbs make
  good immunogens
• But nucleic acids, simple polysaccharides and
  lipids dont due to their repeating monomeric
  structure
• c. appropriate physical form
• insoluble forms are more readily phagocytosed
  and thus are better immunogens than soluble forms
  which are not as often digested by phagocytes.

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• 3. What are the important extrinsic properties of
  immunogens?
• a. dose of immunogen
• in mammals 10 µg- 1 g are effective
• extremely high or low doses may invoke
  tolerance suppress the immune response
• b. route of administration
• those administered parenterally are more
  effective than oral or topical routes- due to
  greater degradation
• c. foreign nature
• if it is like a self antigen then tolerance
  will prevent a
• response.

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4. What is an epitope? What is another name for
it?

• The portion of the antigen that the antibody or
  TCR interacts with Antigenic determinant

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• 5. What cells have the following and what is the
  function of the following in relation to antigen
  presentation to T lymphocytes?
• a. T Cell Receptor (TCR)
• found on T cells
• bind a peptide antigen only when it is bound to
  a self protein the MHC protein

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• b. MHC
• Major Histocompatibility Complex Proteins
• In humans collectively called Human leukocyte
  antigens
• Collectively fxn as antigen presenting molecules
• 1) Class I
• Found on the surface of all nucleated cells
• 2) Class II
• found only on the surface of B lymphocytes,
  macrophages, and dendritic cells

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• 6. What coreceptor do the following cells express
  and what do each bind to?
• a. TH cells
• CD4 protein
• Bind only to Class II proteins
• b. TC cells
• CD8 protein
• Bind only to Class I proteins

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• C. T Lymphocytes
• 1. How do cytotoxic T cells kill?
• Contact starts w/
• TCR/CD8 binding to
• APC
• Degranulation
• Perforin inserts
• itself in membrane
• Forms a pore
• Granzymes enter cell and trigger apoptosis

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2. How are NK cells similar and different from
cytotoxic T cells? What kinds of cells do they
kill

• Similar in their ability to kill cancer cells and
  cells infected w/ intracellular pathogens like
  viruses
• Differ because they are not specific but part of
  innate immunity
• Kill cancer and virally infected cells

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5. How are T-inflammatory cells activated and
what do they stimulate?

• Also called TH1 cells are activated by APC
  macrophages (MHC II)
• They then produce cytokines promoting
  phagocytosis inflammation

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4. How do B cells TH2 cells work together to
produce an activated B cell?

• B cells bind the antigen by the Ig receptor on
  their surface
• The antigen antibody complex is endocytosed
• Antigen is degraded processed then presented
  to TH2 cell
• This stimulates the TH2 cell to release cytokines
• The cytokines stimulate the same B cell to divide
  into plasma memory cells

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D. Antibodies

• 1. Draw and label a basic IgG antibody

Antigen binding sites
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• 2. List the 5 classes of antibodies, give their
  major functions, where they are found and any
  other distinguishing characteristics

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• 3. What is the clonal selection theory?

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4. Draw a graph to represent the primary and
secondary antibody responses in serum. What does
the graph clearly show?
The graph clearly shows that the secondary
response is greater than the primary Response.
In the primary response IgM is produced and in
the secondary response IgG is produced.
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• 5. What are the 4 major potential functions of an
  antibody response?
• a. Viral neutralization/Opsonization bind to
  surface of virus or bacteria block binding to
  host cells enhance phagocytosis
• b. Agglutination Ab-mediated clumping
• c. Precipitation Ab cross-links soluble
  antigens to bring them out of solution to
  enhance phagocytosis
• d. Activation of complement system Ab binding
  to bacterial surface triggers the complement
  cascade

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• 6. Complement
• a. What is complement?
• a group of proteins that work together to
  produce a variety of innate and adaptive immunity
• b. What are the 2 paths for activation?
• Perperdin or alternate pathway (innate)
• Classical pathway (Adaptive)
• c. What are the 3 potential outcomes
• 1) opsonization
• 2) MAC attack
• 3) inflammation

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E. Immunity and Prevention of Infectious Disease

• Natural immunity
• How do animals acquire natural active immunity?
• When they get an infection that then initiates
  an adaptive immune response
• This generates memory T and B cells that will
  usually protect from subsequent exposures

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• b. In the following disorders what part of the
  immune system is lacking and what does it result
  in?
• 1) aggammaglobulinemia
• Have genetic defects in B cells no antibodies
• suffer from recurrent, life-threatening
  bacterial infections but have normal immune
  response to viral infections
• 2) DiGeorges syndrome
• Thymus does not mature thus no production of
  mature T cells
• suffer from serious recurring viral infections
  and other intracellular pathogens

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• 3) AIDS
• can result in total depletion of TH cells
• no effective B cell or T cell immunity
• Suffer from recurrent viral, fungal and
• bacterial infections
• c. How do animals acquire natural passive
  immunity?
• This is the transfer of antibodies from mother
  to child either through the placenta or through
  breast feeding
• No memory results so this is temporary protection

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• 2. Artificial Immunity and Immunizations
• a. What is artificial active immunity?
• When an organism receives injects of a weakened
  organisms or just the antigen
• This then stimulates the adaptive immune system
  memory without developing the disease
• We call this vaccination
• b. What is artificial passive immunity?
• When we receive an injection of antiserum which
  contains the antibodies
• No memory developed- short lived

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• c. What is used for immunization?
• inactivated whole organism, or antigen
• d. What do the following terms mean and how do
  they apply to vaccination?
• 1) toxoid
• exotoxin that has been made nonpathogenic by
  some treatment
• 2) attenuated
• either a mutant strain of a pathogen that has
  lost its virulence or a weakened pathogen
• Can be a problem for immunocompromised people

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• e. Complete on your own from Table 30.2
• Laboratory ID of clinical pathogens

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F. Growth Dependent Diagnostic methods

• 1. Blood cultures
• a. What is bacteremia?
• bacteria in the blood
• When does it occur?
• in healthy individuals it is a result of dental
  surgery or trauma
• What are the common pathogens involved?
• Pseudomonas aeruginosa, E. coli, Klebsiella
  pneumoniae, Staph aureus Streptococcus pyogenes

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• b. What is septicemia and what can be its
  outcome?
• bacteria multiplying in the blood and traveling
  to other areas to initiate new infections
• septic shock
• c. What is the standard blood culture procedure?
• Draw 20 mL of blood asceptically from a vein
• Inject it into 2 blood culture bottles w/
  anticoagulant general purpose culture media
• Incubate 1 in aerobic conditions
• Incubate other under anoxic conditions
• These are checked several times an hour for 5
  days

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• 2. Urine cultures
• a. Why can the interpretation of results be
  confusing
• Disease causes are often normal flora such as E.
  coli
• b. What are some urinary tract infecting
  bacteria?
• E. coli, Klebsiella, Enterobacter, Proteus,
  Pseudomonas, Staph saprophyticus and Enterococcus
  faecalis
• c. What 2 media are commonly used to ID microbes
  found? What do they do?
• blood agar for general growth
• MacConkey or EMB
• Differentiate lactose fermentors from
  nonfermentors and eliminate Staphs (common
  contaminants)

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• 2. Fecal Cultures
• a. What is especially important with these
  samples?
• proper collection and storage
• to much delay between sampling and processing
  may interfere with the detection of Shigella and
  Salmonella
• 3. Wounds Abcesses
• a. What is the best sampling method for
  abscesses?
• aspirate the pus with a sterile syringe after
  disinfection of the skin surface around the site

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• b. What are some bacteria commonly found under
  these conditions
• S. aureus, Pseudomonas aeruginosa and
  Bacterioides and Clostridium
• 5. Culture of Anaerobic Microbes
• a. What are 3 ways this media differs from the
  media for aerobic microbes?
• 1)richer in organic constituents
• 2)contain reducing agents to remove O2
• i.e. thioglycollate or cysteine
• 3)contain a redox indicator for detecting
  anoxic conditions

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• b. What are specimen collection, handling and
  processing designed to do?
• prevent Oxygen contamination
• c. What are some of the ways an anoxic
  environment is created for culturing of these
  bacteria?
• Use environments with Oxygen free gas mixture
  like CO2 and N2
• remove O2 from a jar with some chemical means
  like a H2 generator in the presence of palladium
  catalyst it will form water pulling the O2 out of
  the air in the jar

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G. Immunology and Clinical Diagnostic methods

• How is direct agglutination used in blood typing?

Neg
Pos for B
Pos for A
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• b. Distinguish between direct and indirect ELISA
  test
• Direct uses Antibodies to the antigen of
  interest attached to the wells of a microtiter
  plate
• Add patient serum that is suspected of
  containing the antigen to well
• Detect with antivirus antibody with an enzyme
  attached that will cause a color change when the
  substrate is added
• So in the end you have detected the presence of
  the actual antigen

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• Indirect uses antigen attached to the microtiter
  plate
• Add patient serum and if antibody is present it
  attaches to antigen
• Add anti-IgG with conjugated enzyme if Ab is
  present it attaches
• Add substrate and wait for color change
• IN the end what you have detected is the presence
  of the Ab (not the antigen)

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