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Immunology - DVM year 1 > Exam 2: Dr. Pharr Immunity Mediated by B-cells and Antibodies > Flashcards

Exam 2: Dr. Pharr Immunity Mediated by B-cells and Antibodies Flashcards

1
Q

What happens in the first week of the primary immune response?

A
  1. Recognition of antigen
  2. Activation by helper T cells. Formation of a primary focus
  3. Differentiation to short-lived plasma cells
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2
Q

What is a primary focus?

A

A pool of B cells resulting from the proliferation of antigen activated B cells over the course of about 3-4 days

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3
Q

What do short-lived plasma cells produce?

A

IgM to clear the infection

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4
Q

In the second week of the primary immune response, what steps are taken to protect against future infections with the same pathogen?

A

Development of antibodies with a new heavy chain isotype and with a higher affinity for epitopes derived from the original pathogen
Development of memory B-cells and long lived plasma cells

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5
Q

How many days are there before an immune response can be seen for the first time? Second time?

A

7-10

3-5

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6
Q

what is the outcome of signal one in the first week of the primary immune response?

A

Prepares B cells for collaboration with effector helper T cells

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7
Q

What is formed in the second week of a primary immune response?

A

Germinal centers

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8
Q

What is a germinal center?

A

A site of B cell proliferation in the B cell area of secondary lymphoid tissues

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9
Q

What are the functions of germinal centers?

A

Isotype switching
Somatic hypermutation
Differentiation into either antibody-secreting long-lived plasma cells or memory B cells

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10
Q

What does isotype switching allow for?

A

Efficient elimination of the pathogen

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11
Q

What happens in the process of somatic hypermutation?

A

Point mutations are generated in the variable region of the heavy chain and light chain genes
B cells in the germinal center are then elected for high affinity recognition of the original antigen epitope

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12
Q

What does somatic hypermutation allow for?

A

Efficient recognition of the pathogen

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13
Q

What does germinal center differentiation into either antibody-secreting long-lived plasma cells or memory B cells allow for?

A

Protection from reinfection and disease

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14
Q

What will long-lived plasma cells do?

A

Migrate to the bone marrow and secrete the higher affinity and isotype switched antibody that is observed during the later part of the immune response

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15
Q

What will memory B cells do?

A

Maintain surveillance of secondary lymphoid tissues

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16
Q

What characteristics of the antibody response will be helpful in preventing disease from the same pathogen?

A
  1. The antibody response occurs more rapidly
  2. Antibody levels will be higher than the level attained with the primary response
  3. The antibodies produced will have a higher affinity for the antigen epitope
  4. The antibody will consist of an isotype different from IgM
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17
Q

What are the 2 types of antigens encountered by B cells?

A

Thymus-dependent protein antigens

Thymus-independent non-protein antigens

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18
Q

What do thymus-dependent protein antigens require?

A

T cell help for B cell proliferation and differentiation

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19
Q

What can the repeated epitopes of thymus-independent antigens do?

A

Engage a number of B cell receptors

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20
Q

What is the multitude of signals with the thymus-independent antigen sufficient to do?

A

Induce B cell proliferation and differentiation to short lived plasm cells secreting IgM
This results in an early IgM response to an infection

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21
Q

Describe mature naive B cells

A

Diverse repertoire of antibody specificities–respond to thymus-dependent antigens
Require T cell help for activation
Located in secondary lymphoid tissues
Recirculate between the blood and lymphatics

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22
Q

Describe marginal zone B cells

A

Respond to pathogens in the blood
Differentiate to short-lived plasma cells secreting IgM
Located in the marginal zone of the spleen where blood is filtered

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23
Q

Describe B1 B cells

A

Respond to pathogens entering the major body cavities
Differentiate into short lived plasma secreting IgM
Located in the peritoneal and pleural cavities

24
Q

What does IgM do?

A

Protects the bloodstream

25
Q

What does IgG do?

A

Protects the bloodstream, extracellular spaces in tissues, and lymphatics

26
Q

Describe IgA: Where is it? What does it do?

A

First line of defense
Present in mucous secretions
Protects epithelial surfaces

27
Q

What does IgE do?

A

Second line of defense behind IgA

Stimulates an inflammatory response

28
Q

What does IgD do?

A

Participates as a BCR on naive B cells

29
Q

In what general ways do antibodies clear infections with extracellular pathogens and their products?

A

Focus defense mechanisms onto the pathogen itself–the antibody links that pathogen with the leukocytes and plasma proteins that will eliminate it

30
Q

What do phagocytes express?

A

Fc receptors for antibody bound to a pathogen

Complement for C3b bound to a pathogen

31
Q

When is the effector function of IgM produced?

A

In the primary response to an infection

32
Q

Is IgM recognized by Fc receptors of phagocytes?

A

No

33
Q

How does IgM clear an infection?

A

It is a very potent activator of complement

It is specialized to activate complement efficiently upon binding to the pathogen

34
Q

What is C1q?

A

The first component of the classical pathway of complement activation

35
Q

What must C1q do to become activated?

A

Bind to 2 or more antibody heavy chains, which requires multiple molecules of IgG bound to the pathogen

36
Q

What are the main effector functions of IgG?

A

Neutralization*
Opsonization*
Antibody-dependent cell-mediated cytotoxicity (ADCC)

37
Q

What is neutralization?

A

Antibodies can prevent infection by coating the surface of a pathogen and therefore prevent the pathogen from binding to healthy cells

38
Q

What is an opsonin?

A

A substance that enhances phagocytosis

39
Q

What is involved with opsonization?

A

Macrophages and neutrophils

40
Q

What is involved with ADCC?

A

NK cells

41
Q

What do NK cells do in ADCC?

A

They use their Fc receptors to bind to antibody-coated cells, which they kill by inducing apoptosis

42
Q

What are the antibody coated cell recognized by NK cells?

A

Virus infected cells

Tumor cells

43
Q

When is the IgA isotype formed?

A

After a primary response to a pathogen that invaded the body through the internal epithelial linings

44
Q

What secretes IgA?

A

Long lived plasma cells

45
Q

How does IgA provide the first line of defense against reinfections?

A

IgA is present in mucus secretions that cover the internal epithelial lining of the body

46
Q

How does IgA protect the epithelial surfaces?

A

Neutralization

47
Q

Does the IgA dimer activate complement?

A

No

48
Q

What does the primary response to parasite and some bacteria result in?

A

Long lived plasma cells secreting IgE

49
Q

What is IgE important in?

A

Reinfections with parasites that invade the internal epithelium

50
Q

What does IgE provide mast cells?

A

The ability to sense pathogens

51
Q

Where are mast cells located?

A

Beneath the epithelial surfaces of the skin, respiratory tract, and gastrointestinal tract

52
Q

What do mast cells express?

A

Fc receptors for IgE

53
Q

What happens when an antigen binds IgE on the surface of mast cells?

A

The release of histamine stimulates an inflammatory response

54
Q

How does IgE provide a second line of defense agains reinfection with pathogens that invade the intestinal epithelium and enter the underlying tissue?

A

IgE is bound to the surface of mast cells and is responsible for mast cell activation in response to pathogen invasion

55
Q

What do eosinophils express?

A

Fc receptors for IgE

Immunology - DVM year 1 (35 decks)

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