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Sem 2: Immuno > Antigens Block 4 Toka > Flashcards

Antigens Block 4 Toka Flashcards

1
Q

What is an antigen?

A

An antibody generator

induces an immune response when it enters the body

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2
Q

What do antigens bind to?

A

Antibodies, MHC molecules or lymphocyte receptors like TCRs and BCRs

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3
Q

What are the 2 subcategories of antigens?

A
  1. Immunogens
  2. Haptens
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4
Q

What are immunogens? Give examples

A

antigens that directly stimulate an immune response

Ex: polysaccharides

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5
Q

What are haptens? give an example

A

antigens that INDIRECTLY induce an immune response, only when bound to a protein

Ex: lipids

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6
Q

What is immunogenicity?

A

when antigens induce an immune response that causes T and B cells to make antibodies

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7
Q

What is the difference between immunogenicity vs antigenicity?

A

Immunogenicity focuses on the ability of an antigen to induce an immune response

while antigenicity focuses on the ability of an antigen to be recognized by the immune system

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8
Q

What is antigenicity?

A

ability of an antigen to bind to receptors on T and B cells and initiate an immune response

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9
Q

What is an epitope?

A

An antigenic determinant

part of the antigen that actually induces the immune response and binding of T and B lymphocytes

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10
Q

True or False: Antigens can have many epitopes

A

TRUE

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11
Q

What are the sources of antigens?

A

Infectious agents like:
1. Bacteria
2. viruses
3. Parasites
4. Fungi

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12
Q

What are structural viral antigens vs non structural?

A

Structural- found in envelope or nucleocapsid of virus

Non structural- proteins that the virus makes when attacking a cell

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13
Q

What are some fungal antigens?

A
  1. Chlamydoconidia
  2. Blastoconidia
  3. Hypha
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14
Q

Why are parasitic antigens challenging to control?

A

Because the changes in a parasite are involved in changes in the antigen structure

difficult to break the cycle

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15
Q

What are cell surface antigens?

A

They dont induce an immune response unless transferred to different hosts

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16
Q

What factors affect immunogenicity of antigens?

A
  1. Foreignness
  2. Size
  3. Chemical composition
  4. Physical properties
  5. Degradability
  6. Genetic factors
  7. Age
17
Q

How does the size of the antigen affect immunogenicity?

A

The larger the antigen the more immunogenic (can be recognized easier)

18
Q

How does the chemical composition of the antigen affect immunogenicity?

A

The more complex the molecule the more antigenic determinants that can be recognized by the immune system

19
Q

What age group is most immunogenic?

A

middle age! best protected

old and young are less capable of recognizing pathogens

20
Q

What is the chemical nature of antigens?

A
  1. Proteins (largest group of antigens)
  2. polysaccharides (good immunogens)
  3. Nucleic acids
  4. Lipids
21
Q

nucleic acids

A

weak antigens that become immunogenic when conjugated to a protein

22
Q

What is an adjuvant?

A

A substance that enhances immune response to antigens

this is added to vaccines

23
Q

What are T- independent antigens?

A

those that dont require help from helper T cells

directly stimulates B cells to make antibodies

does not produce memory B cells tho

Ex: lipopolysaccharides

24
Q

What is the properties of T independent antigens?

A

Polymeric structure that has the same antigenic determinant that repeats throughout its length

Because of this BCR can bind many at the same time

25
Q

What are the cons of T independent antigens?

A

they may activate lymphocytes polyclonally- meaning B cells have different antigenic specificity that might not be as effective

they are resistant to degradation- making them last longer in the body

binds to BCRs

26
Q

What are T-dependent antigens?

A

antigens that req. helper T cells

they indirectly stimulate B cells to make antibodies

most are proteins

contains only few copies of antigenic determinants

binds to TCRs

27
Q

Which of the following best describes T-independent antigens?
a) Antigens that require T cells for activation

b) Antigens that activate B cells directly without the involvement of T cells

c) Antigens that activate both B cells and T cells simultaneously

d) Antigens that are resistant to degradation in the body

A

b) Antigens that activate B cells directly without the involvement of T cells

28
Q

Which of the following factors can affect the immunogenicity of a substance?
a) Route of administration
b) Chemical composition
c) Dose
d) All of the above

A

d) All of the above

29
Q

Which of the following is NOT a source of antigens?
a) Parasites
b) Bacteria
c) Fungi
d) Prions
e. Viruses

A

d) Prions

30
Q

What are superantigens?

A

antigens that can activate alot of lymphocytes at 1 time (non specifically)

Activates pro inflammatory cytokinesis leading to system toxicity

Sem 2: Immuno (17 decks)

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