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Immunohematology and Serology > Intro to Immuno Ch 1, 2, & 3 > Flashcards

Intro to Immuno Ch 1, 2, & 3 Flashcards

1
Q

Define serology

A
  • The study of the reaction and properties of the serum components of the blood. Deals mostly with antibody and antigen reactions in vitro
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2
Q

What elements of the immune system allow it to recognize antigens (3)?

A
  • Secreted and membrane-bound immunoglobulins
  • T-cell receptors
  • Products of the genes of the MHC
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3
Q

What are the basic antigen characteristics that determine immunogenicity (6)?

A
  • Foreignness
  • Molecular size
  • Chemical complexity
  • Susceptibility to recognition, uptake, and degradation by antigen presenting cells
  • Method of introduction of the antigen
  • Presence of certain chemicals that can act as immune adjuvants
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4
Q

Define recognition.

Define uptake.

A
  • Recognition: body has to know it is foreign

- Uptake: how well the body takes the antigen and presents it

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5
Q

Define Foreignness

A
  • Refers to the phylogenetic relationship between the host and the antigen
  • Generally, the further apart, the better the response
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6
Q

Define autoantigen

A
  • self antigens
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7
Q

Define alloantigen

A
  • antigens from other members of same species
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8
Q

Define heteroantigen

A
  • antigens from a species different from the host
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9
Q

Define heterophile antigens

A
  • generate unexpected cross-reaction due to similar epitopes

- The antigens are so similar that they can’t be differentiated

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10
Q

Size and Complexity

- Describe immunogenicity as related to molecular size

A
  • Larger antigens have stronger immunogenicity (generally speaking)
    • Nonimmunogenic—less than 1000 daltons
    • Sometimes immunogenic—1000–6000 daltons
    • Immunogenic—more than 6000 daltons
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11
Q
  • What are haptens?

- What do they need to stimulate immunogenicity?

A
  • Small compounds that cannot stimulate an immune response unless linked to a much larger immunogenic molecule
  • Carrier molecule—larger molecule that a hapten is linked to
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12
Q

Size and Complexity

  • how is size linked to chemical complexity?
  • what are the exceptions and why are they exceptions?
A
  • Larger, more complex antigens may be better recognized and more susceptible to phagocytosis
  • Bacteria use complexity, or lack thereof, to their advantage. Simplicity is a trick many of them use to survive
  • Exceptions:
    • Small compounds such as glucagon (3400 daltons) can be immunogenic
    • Large homopolymers not immunogenic because numerous repeating units are simple
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13
Q

Proteins:

  • how strong immunogenic?
  • why?
A
  • Strong immunogens
    • Large size and complexity
    • Linear and conformational epitopes
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14
Q
  • What type of molecules are thymic-dependent antigens?

- What does that mean?

A
  • Proteins

- After being processed by Ag presenting cells, a relevant epitope is presented to a T cell and stimulates it

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15
Q

Carbohydrates

  • Where are they on the immunogenicity scale?
  • What type of response do they generate?
  • What type of antigens are they generally seen in?
A
  • Less immunogenic than proteins but more so than lipids and nucleic acids
  • Usually a T-independent response
  • Important in blood groups, bacteria, fungi, tumor associated antigens
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16
Q

Lipids and nucleic acids
Where are they on the immunogenicity scale?
- In what instance does immunogenicity occur?

A
  • Not immunogenic unless covalently linked to an immunogenic carrier
  • Antibody to DNA does occur in SLE
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17
Q

Antigenic Determinants

  • AKA
  • what is the role?
  • on what cell are they found?
A
  • Epitopes
  • These are what make an antibody attach to a specific antigen
  • the antigen
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18
Q
  • What types of cells recognize epitopes?

- What happens after they recognize them?

A
  • Recognized by and binds to a particular immunoglobulin (antibody) or T-cell receptor
  • An antibody-producing cell clone synthesizes immunoglobulins that recognize a particular antigenic determinant
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19
Q

Why Are Antibodies Important? (4 reasons)

A
  • Key in helping us fight infection
  • Vital to many diagnostic tests
  • In blood banking, testing is about 70:30 Ab:Ag
  • Biotechnology industry
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20
Q

Why are antibodies so important in blood banking?

A
  • We test for antibodies because we don’t want to give a patient a product that they have antibodies for. The patient would adversely react to the product being given.
21
Q

Discovering the General Structure of IgG

  • what chemicals were used to split the disulfide bonds?
  • Where did they split the molecule?
A
  • Urea and mercaptoethanol
22
Q

Discovering the General Structure of IgG

  • what enzymes were used to split the disulfide bonds?
  • Where did they split the molecule?
A
  • enzyme papain

- cuts above the heavy chain to heavy chain disulfide bond, which split the constant region from the variable region

23
Q

Discovering the General Structure of IgG

  • What does Fc stand for, and what region of the molecule is it?
  • What does Fab stand for, and what region of the molecule is it?
A
  • Fragment crystallizable (Fc)
    • constant region
  • Fragment antigen binding (Fab)
    • changeable/variable region
24
Q

What region contains the antigen binding site?

A
  • Found at the N-terminal end of the heavy chain and the light chain (paratope)
  • the variable region
25
Q

What is the paratope?

A
  • the binding site on the antibody
26
Q

General Structure IgG

- binding region

A
  • The part of the antigen that it binds to is called the epitope
  • Epitope on antigen
  • Paratope on antibody
27
Q

General Structure IgG

- What type of bonds occur between the paratope and the epitope?

A
  • Bound by noncovalent bonds

- - Van der Waals bonds, hydrogen bonding, electrostatic or ionic bonds, and hydrophobic and hydrophilic interactions

28
Q

Define:

  • Affinity

- Avidity

A
  • Affinity “how much do they like each other”
    • The sum of the attractive interaction between the paratope and the epitope
  • Avidity = total number of binding sites
    • The sum of the binding of all the paratopes and the epitopes
29
Q

General Structure

- the light chain

A
  • Variable light chain domain (VL)

- Constant domain of the light chain (CL)

30
Q

General Structure

- The heavy chain

A
  • One variable domain VH
  • Three or four constant domains
    – CH1, CH2, CH3, CH4
    Numbering begins next to constant region
31
Q

Where is the variable domain found and why?

A
  • The variable domain will always be found at the amino terminus of the molecule, as the part that comes in contact with the different antigens has to have the ability to change
32
Q

What two characteristics to the heavy and light chains have in common?

A
  • Domains of about 110 amino acids

- Intrachain disulfide bonds that form loops causing a globular area to form

33
Q

General Structure: Variable regions of heavy and light chains

  • why do they have different binding abilities?
  • where are these regions?
  • where are the framework regions located?
A
  • Different binding abilities due to hypervariable regions
    – 3 in the VL, 3 in the VH
    – Also called Complementary
    Determining Regions (CDRs)
    — Shape is complementary to antigen shape
  • Framework regions located between hypervariable regions
34
Q

Classes, Subclasses, and Light Chains: the different classes

- what leads to their different biologic functions?

A
  • Differences in the heavy chains lead to their different biologic functions
35
Q

Classes, Subclasses, and Light Chains: the different classes

  • describe the Fc region - what is it made up of?
  • describe the importance of the biologic activity here
A
  • Made up of only parts of the heavy chain

- The difference in biological activity is due to heavy chain differences in the Fc region

36
Q

Classes, Subclasses, and Light Chains: IgG

  • what % of immunoglobulins?
  • what type of heavy chains present?
A
  • 80% of the immunoglobulin in serum, highest concentration of all Ig
  • Heavy chains called gamma (γ) heavy chains
37
Q

Classes, Subclasses, and Light Chains: IgG

  • what does its high diffusion coefficient allow it to do?
  • what are the subclasses and how did they get their distinctions?
A
  • High diffusion coefficient so it travels to extravascular space to protect
  • Subclasses numbered according to serum concentration
    • IgG1
    • IgG2
    • IgG3
    • IgG4
38
Q

Classes, Subclasses, and Light Chains: IgG

- what are the 4 ways in which it helps fight infection in serum?

A
  • Opsonizes
  • Activates Complement
  • Neutralizes toxins and viruses
    • Blocks binding
  • Enhances clearance
    • Causes agglutination and precipitation through cross-linking
39
Q

Classes, Subclasses, and Light Chains: Subclasses of IgG

  • Which are best at opsonization
  • Which are best at activating complement?
  • Which does not activate complement?
A
  • IgG1 and IgG3 are best at opsonization
  • IgG3 > IgG1 >IgG 2 at activating complement
  • IgG4 does not activate complement
40
Q

Classes, Subclasses, and Light Chains: Subclasses of IgG

  • Which can pass through the placenta?
  • What is the half-life of each?
A
  • IgG1, IgG3, and IgG4 can pass through the placenta and protect the fetus
  • Half life of IgG1, IgG2, and IgG4 longest of the immunoglobulins at 23 days
  • The half life of IgG3 is 8 days
41
Q

When a baby is born, how can you tell if it was protected or exposed to an antigen?

A
  • Diagnosis based on knowledge about the different immunoglobulins
    • IgG means mom gave the baby protection
    • IgM means baby was exposed to antigen after birth
42
Q

Classes, Subclasses, and Light Chains: IgM

  • what % of immunoglobulins?
  • describe the structure
A
  • 5–10% of the immunoglobulin in serum
  • Pentamer composed of 5 of the 2 heavy chain and 2 light chain units
  • Starfish-like shape
    Fc regions in the center
    Fab arms extended out
43
Q

Classes, Subclasses, and Light Chains: IgM

  • molecular weight?
  • what is another name for this type f immunoglobulin?
A
  • Largest immunoglobulin
    • 900,000 daltons
  • Called a macroglobulin because of large molecular weight
44
Q

What is another name for a tumor that can produce IgM?

A
  • Tumor in which the tumor plasma cells make IgM is called a macroglobulinemia
45
Q

Classes, Subclasses, and Light Chains: IgM

  • what is the avidity?
  • what links the monomers together?
A
  • 10 paratopes could bind 10 epitopes
    • If the antigens are small and there is no steric effects
    • Usually some steric interactions so often only five paratopes bind to epitopes at one time
  • Held together by a J chain by disulfide bonds
46
Q

Classes, Subclasses, and Light Chains: IgM

  • when does this Ig come in when an antigen is present?
  • why is affinity so low?
A
  • First immunoglobulin produced in response to an antigen

- Produced without the somatic mutation events that improve affinity

47
Q

Classes, Subclasses, and Light Chains: IgM

  • What do elevated levels in a newborn indicate?
  • Can it cross the placenta?
  • Can it enter extravascular spaces?
  • what is the half-life?
A
  • Elevations in IgM after birth indicate an infection
  • Does not cross the placenta
  • Does not enter extravascular spaces
  • Half-life is 10 days
48
Q

Classes, Subclasses, and Light Chains: IgM on the B cells

  • what role does it serve?
  • what is the structure?
  • what differences does the structure have compared to the free-floating Ig?
A
  • Receptor for specific antigen
  • Monomeric not pentameric
  • Slightly different Fc region
    • Transmembrane and cytoplasmic regions

Immunohematology and Serology (8 decks)

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