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Micro Exam 3 > Material Learned After Exam 3 > Flashcards

Material Learned After Exam 3 Flashcards

1
Q

What are the 2 signals needed to trigger a B cell?

A
  1. Antigen BCR interaction

2. T cell cytokines

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2
Q

How can the expression of MHC molecules be increased?

A

Via production of cytokines during
1. MHC I (aka innate immune response)
and
2. MHC II (aka adaptive immune response)

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3
Q

How are T8-lymphocytes activated?

A

Epitope from endogenous antigenous are bound to MHC I molecules via/facilitated by dendritic cells

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4
Q

T/F: All nucleated cells have MHC I molecules

A

True

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5
Q

What allows T4 lymphocytes to recognize epitopes of exogenous antigens and discriminate self from non-self?

A

MHC II molecules

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6
Q

What type of cell makes MHC II molecules?

A

Antigen presenting cells (APC)

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7
Q

T/F: T cells, B cells, and natural killer (NK) cells are all the same.

A

False, NK cells are not the same as T and B cells

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8
Q

What is the function of natural killer cells?

A

To destroy cancer cells & cells infected w/ intracellular pathogens

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9
Q

Describe the mechanism used by natural killer cells.

A
  1. Cell is targeted if it lacks normal MHCs or specific proteins
  2. NK cell injects granzymes and perforins into the target cell which induce apoptosis within the target cell
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10
Q

T/F: Natural killer cells need past exposure in order to recognize foreign cells

A

False

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11
Q

T/F: Natural killer cells do not exhibit memory w/ target cells and are not enhanced.

A

True

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12
Q

What are TH17 cells?

A

CD4+ T helper cells that produce the proinflammatory cytokine interleukin-17.

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13
Q

What is the function of TH17 cells?

A

They protect host from fungal/bacterial infections at muscosal surfaces (ex. intestinal lining)

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14
Q

What directly regulates the differentiation of TH17 cells in the intestine and why is this significant?

A

Regulated by: molecular circadian clock

Significance: suggests that nutrition and light are imp environmental factors that directly regulate the immune response

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15
Q

These are glycoprotein molecules that interact specifically w/ antigenic determinants.

A

Antibodies/immunoglobulins (Ig)

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16
Q

Name 2 functions of antibodies/immunoglobulins (Ig).

A
  1. act as antigen receptors of B cells

2. act as antibodies (soluble proteins) when secreted

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17
Q

Name 3 substances that antibodies/immunoglobulins (Ig) can be found in.

A
  1. Serum
  2. Milk
  3. Gastric
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18
Q

Describe the antigen binding sites.

A

Pockets located at the ends of fork-like structure of antibody
-contains a variable region thus resulting in a variety of antigen binding site shapes to fit a wide range of antigens

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19
Q

What are the 5 major classes of antibodies/immunoglobulins (Ig)? What differentiates them? Which class is the most commonly found in the body?

A
  1. IgG<–most commonly found
  2. IgA
  3. IgM
  4. IgD
  5. IgE
    - Differentiated from each other by their amino acid sequence
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20
Q

Describe the structure of IgG.

A
  • 4 poypeptide chains (2 heavy and 2 light chains)

- Interaction b/w light and heavy chains creates an antigen-binding site

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21
Q

Where are each class of antibody/immunoglobulin found/involved in?

A
  • IgM & IgG–>found in blood
  • IgA–>found in secretions from mucous membranes (ex. spit, tears, breast milk)
  • IgE–>involved in parasite immunity & allergies; functions as an antibody that binds to eosinophils
  • IgD–>found on surface of B cell
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22
Q

What are eosinophils?

A

White blood cells

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23
Q

What is class switching?

A

Change in antibody class that’s secreted by plasma cells under the influence of helper T cells

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24
Q

Describe the primary antibody response.

A
  1. Initial exposure to antigen
  2. Lag/latent period (several days-weeks); no antibodies detectable in blood
  3. B cell differentiation in plasma cells; antibodies are secreted
  4. IgM is secreted first and then IgG
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25
Q

What is an antibody titer?

A

A measure of serum antibody concentration

-is the reciprocal of the highest dilution of antiserum that gives a positive reaction

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26
Q

What is the anamnestic response?

A

Renewed rapid production of antibodies on the second/subsequent encounter with the same antigen

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27
Q

What are the 5 actions that antibodies can perform when a foreign cell is detected?

A
  1. Precipitation
  2. Neutralization
  3. Complement Fixation
  4. Agglutination
  5. Opsonization
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28
Q

Define: Precipitation

A

Soluble antigens (Ag) bind to soluble antibodies (Ab) to form immune complexes

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29
Q

Define: Neutralization

A

Antibody (Ab) binds to antigen (Ag), preventing the antigen from binding to the host cell

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30
Q

Define: Complement Fixation

A

Interaction between specific antitoxin antibodies and toxic antigens can prevent the toxic antigen from entering host cells

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31
Q

Define: Agglutination

A

Insoluble antigens (ex. viral or bacterial cells) are cross-linked together using antibodies

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32
Q

Define: Opsonization

A

Antibody binds to antigens on a larger molecule/cell, making it recognizable to a phagocytic cell (i.e. antigens will get eaten)

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33
Q

What are the 4 classes of immunity? How are each acquired?

A
  1. Active Immunity
    • via personal immune response to a microbe
  2. Passive Immunity
    • you receive preformed immunity made by another person (ex. mother->baby)
  3. Natural Immunity
    • via normal life experiences (not induced via medical means)
  4. Artificial Immunity/Immunization
    • produced purposefully through medical procedures
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34
Q

What is the difference between how natural passive and natural active immunity is acquired?

A

Passive: antibody transfer across the placenta or in breast milk

Active: acquisition of infection that initiates an adaptive immune response

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35
Q

Exposure to a controlled dose of a harmless antigen to induce formation of antibodies is called…

A

Artificial active immunity (vaccination)

36
Q

Injection of an antiserum derived from an immune individual is called…

A

Artificial passive immunity

37
Q

Immune serum globulin, specific immune globulin, and antisera/antitoxins of animal origin all fall under what class of immunization?

A

Passive Immunization

38
Q

This immunization method is used to prevent measles, hepatitus A and in replacing antibodies in immunodeficient patients. It’s injected intramuscularly and protection lasts 2-3 months. What is the name of this serum?

A

Immune serum globulin (ISG) (aka Gamma Globulin)

-form of artificial passive immunity

39
Q

This serum is obtained from a more defined group of donors, patients who are in a hyperimmune state after infections which means it contains higher titers of specific antibodies. What type of serum is this?

A

Specific immune globulin (SIG)

-it contains a higher concentration of specific antibodies than ISG

40
Q

T/F: Immunization with dead or inactivated material is just as effected as with live cells or a virus.

A

False. Immunization w/ live cells or a virus is more effective.

41
Q

T/F: Most agents used for immunization are either inactivated pathogens or active forms of microbial products such as toxins.

A

False. Most are either attenuated/inactivated pathogens or inactivated forms of microbial products.

42
Q

The process of generating an artificial active immune response by exposure to an antigen/antigen mixture is known as…

A

Immunization/vaccination

43
Q

T/F: Vaccination involves exposing a person to material that is pathogenic but not antigenic.

A

False. Material is antigenic, not pathogenic.

44
Q

T/F: For most pathogens, you only need to be immunized once in your life.

A

False, immunization usually involve a series of 2ndary or booster immunization to produce a 2ndary response and a higher antibody titer.

45
Q

What is the purpose of vaccination?

A

To stimulate a primary and secondary anamnestic response to prime the immune system for future exposure to a virulent pathogen.

46
Q

Define: Herd Immunity

A

Collective immunity through mass immunization confers indirect protection on non-immune members
-imp force in preventing epidemics

47
Q

Why is it difficult to design vaccines for latent or persistent viral infections?

A
  1. Host’s natural immunity can’t clear the infection

2. Artificial immunity must then outperform the host’s response to a natural infection

48
Q

Name 4 new strategies of administering immunization.

A
  1. Synthetic peptides (ex. foot and mouth virus)
  2. Recombinant-vector vaccines (ex. rabies vaccine)
  3. Recombinant-antigen vaccines (ex. hepatitis B vaccine)
  4. DNA vaccines (based on expression of cloned genes in host cells
49
Q

Describe the Trojan horse vaccine.

A
  1. Genetic material from an infectious agent is inserted into a live, nonpathogenic carrier microbe
  2. Recombinant microbe multiplies and expresses the foreign gene
  3. Vaccine recipient will be immunized against the microbial antigens
50
Q

Structural components common to a particular group of infectious agents are known as…

A

Pathogen-associated molecular patterns (PAMPs)

-includes polysaccharides, lipids, proteins, and nucleic acids

51
Q

Soluble and membrane-bound host proteins that interact w/ PAMPs and promote phagocytosis are known as…

A

Pattern recognition receptors (PRRs)

-found on the surface of macrophages, monocytes, neutrophils and dendritic cells

52
Q

T/F: PRRs were first recognized in the fruit fly and were called Toll receptors.

A

True

53
Q

Define: Toll-like receptors (TLRs)

A

Structural, function, and evolutionary homologs of the Toll receptors
-widely expressed on mammalian innate immune cells

54
Q

Define: Nod-like receptors (NLRs)

A

Intracellular receptors of PAMPs that enter the cell via phagocytosis or through pores

55
Q

What structural component of the cell acts as a barrier against PAMPs?

A

Cytoplasmic membrane

56
Q

How does a cell respond to the danger w/out allowing the PAMPs into the cell?

A

Use signal transduction to initiate transcription & translation of host-response proteins, mainly those involved in phagocytosis and inflammation

57
Q

What type of immunity are interferons involved in?

A

Innate immunity

58
Q

Name the 3 major types of interferons (IFN) and each of their functions.

A
  1. IFN alpha: stimulate phagocytes and activates NK cells
  2. IFN beta: stimulate phagocytes, plays a role in inflammation, and mature T and B lymphocytes
  3. IFN gamma: inhibits cancer cells, stimulates B lymphocytes, activates macrophages, and enhances phagocytosis

How: via binding to cell surfaces & inducing changes in genetic expression

59
Q

T/F: Interferon classes are produced dependent on if the response is to viruses, RNA, immune products, or various antigens.

A

False. All 3 IFN classes are produced in response to viruses, RNA, immune products, and various antigens

60
Q

What is the activation mechanism for phagocytes and lymphocytes in adaptive immunity?

A

Signal transduction

61
Q

What structural component do adaptor molecules (that antigen receptors associate with) contain?

A

Immune-Based Tyrosine-Activation Motifs (ITAMs)

62
Q

Define: Immunoglobulin gene superfamily

A

A large number of genes and their products that share structural, evolutionary, and functional features w/ immunoglobulin genes and proteins

63
Q

Fill in the blank: Immunoglobulins (Ig, BCRs), T cell receptors (TCRs), and major histocompatibility complexes (MHCs) are all _____ proteins involved in the _____ immune response.

A

Antigen-binding/adaptive

64
Q

T/F: Major histocompatibility complex (MHC) molecules have a low degree of polymorphism.

A

False. They have a high degree which explains their high diversity which may directly influence the survival of individuals against infectious disease

65
Q

What is the human version of MHC?

A

HLC (human leukocyte antigen)

66
Q

This is a major antigen barrier for tissue transplantation.

A

MHC proteins

67
Q

Describe the steps that take place after a differentiated B cell is exposed to an antigen for the first time.

A
  1. (B cell first acts like an antigen present cell) B cell binds to antigen through its surface antibody (BCR)
  2. TH2 cytokine stimulation activates B cell which grows and differentiates into plasma cells that secrete antibodies targeted against the antigen
68
Q

T/F: Each differentiated B cell is capable of producing BILLIONS of dif antigen-specific proteins each aimed to interact w/ one of the countless antigens in our environment.

A

True

69
Q

Where are the variable domains of antibodies ESPECIALLY dif from one another?

A

Complementarity-determining regions (CDRs)

70
Q

T/F: the antigen-binding site of an antibody is large enough to accommodate the binding of an epitope (10-15 amino acids long)

A

True

71
Q

Ultimately, what is binding.

A

Binding=A function of the folding pattern of the heavy & light polypeptide chains

72
Q

Name 4 ways that allow us to produce a near infinite diversity of antibodies.

A
  1. Somatic recombination/combinatorial joining (mech. exclusive to T and B cells)
  2. Random heavy and light chain reassortment
  3. Coding for joint diversity (i.e. splice site variability)
  4. Somatic hypermutation (B cells) of V regions after antigen exposure
73
Q

Name 2 ways that somatic recombination could happen.

A
  1. Rearrangement of antibody gene segments

2. Generation of different codons during antibody gene splicing.

74
Q

What is the “Genes In Pieces” hypothesis?

A

Idea that the gene encoding each Ig is constructed from several Ig gene segments.
-during B-cell differentiation, exons for the constant region are joined to one segment of the variable region to produce a gene encoding a complete chain of an antibody

75
Q

This process accounts for antibody receptors having higher antigen-binding strength during the 2nd exposure to antigen compared to the original B cell receptors.

A

Affinity maturation process

76
Q

Compare and contrast the primary and secondary antibody response.

A

Primary: antigen-stimulated B cells multiply & differentiate to form antibody secreting plasma cells and memory cells–Secretes mostly IgM

Secondary: Previous memory B cells transform into antibody secreting cells–Secretes mostly IgG

77
Q

T/F: T cell receptors (TCRs) bind to both self MHC and foreign peptides

A

True

78
Q

T/F: TCRs and MHCs bind directly to peptide antigen

A

True

79
Q

T/F: The CDR1 region of both alpha and beta chains bind to the epitope while as the CDR2 and CDR3 regions bind to the MHC protein

A

False. CDR3=binds to epitope. CDR1 and CDR2=bind to MHC protein

80
Q

Name 3 genetic mechanisms that attribute to the diversity in T cell receptors (TCRs).

A
  1. somatic recombination
  2. random chain reassortment
  3. coding for joint diversity

only occur on distinct gene segments on the alpha and beta chains

81
Q

unresponsiveness/anergy to “self” is called…

A

Tolerance

82
Q

How do T cells acquire tolerance?

A

Lymphocytes are maintained so that they interact only w/ the non-self antigens derived from dangerous pathogens

83
Q

What happens to T cells that fail to develop tolerance?

A

Autoimmunity–inability to differentiate b/w self and non-self resulting in destruction in both

84
Q

Describe the Clonal Selection Theory

A
  • Each antigen-reactive B or T cell has a cell surface receptor for a single antigen epitope
  • when stimulated, the cell replicates
  • when selected, the clone expands
85
Q

Elimination of clones of “self” antigens is known as…

A

Immune tolerance

86
Q

Describe the positive and negative selection processes occurring in the thymus to determine which T cells have achieved tolerance.

A

Positive selection: T cells that interact w/ MHC peptide complexes are retained; T cells that don’t interact w/ MHC-peptide stop growing and die

Negative selection: T cells that pass the positive selection but strongly bind w/ MHC-self peptides are selected against

After both selection processes, any surviving T cells leave the thymus and reenter the lymphatic circulation

87
Q

T/F: More than 99% of T cells that enter the thymus pass the selection process.

A

False, more than 99% do NOT survive the selection process (i.e. clonal deletions occur)

Micro Exam 3 (2 decks)

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