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HUBS191 > lecture 36 - B cells & antibody > Flashcards

lecture 36 - B cells & antibody Flashcards

1
Q

Where do B cells develop?

A

In bone marrow

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2
Q

Where do B cells mature?

A

Bone marrow

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3
Q

What do B cells express?

A

Unique antigen receptors (BCR)

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4
Q

What are Plasma B Cells?

A

Activated B cells that secrete antibody

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5
Q

What is the outcome of maturation of B cells in bone marrow?

A

B cells have immunocompetence and self-tolerance

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6
Q

What is the structure of a B cell?

A

A cell covered in ~100,000 identical, unique B cell receptors that are anchored in the membrane via a transmembrane domain

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7
Q

BCR are usually made up of which antibodies?

A

IgM and IgD

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8
Q

How do individual B cells target specific antigens?

A

They have lots of identical antibodies that have antigen specificity

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9
Q

What are the key components of a BCR?

A

2 identical light chains and 2 identical heavy chains

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10
Q

What is the structure of the light chain of a BCR?

A

Has a variable and constant region

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11
Q

What is the structure of the heavy chain of a BCR antibody?

A

variable and constant regions, a C-terminal hydrophobic stretch that spans the B cell membrane.

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12
Q

What are the light and heavy chains of a BCR joined by?

A

Disulfide bridges

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13
Q

What is a transmembrane domain, in terms of BCRs?

A

A protein spanning a cell membrane that helps bind an antibody to a B cells

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14
Q

What are the 3 functions of antibody/immunoglobulin?

A

Neutralisation, opsonisation, complement activation

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15
Q

What is the alternative term for a BCR antibody?

A

Immunoglobulin (an antibody with a trans membrane domain)

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16
Q

What is neutralisation, in terms antibodies?

A

Antibodies bind to the envelope or capsid of invading viruses and prevent them from undergoing shape changes to enter cells, or blocks toxicity.

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17
Q

What is opsonisation, in terms of antibody action?

A

When antigens bind to the surface of bacteria making them attractive to macrophages and other phagocytic leukocytes.

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18
Q

What is complement activation, in terms of antibody action?

A

Activation of the classical pathway of the complement system, leading to opsonisation, lysis by MAC, etc.

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19
Q

How do antibodies aid in lysis of the cell, via the classical complement pathway?

A

They aid in the attachment of complement proteins to the surface of the cell, where hey can form a MAC (membrane attack complex), which facilitates the formation of a pore which lyses a bacterial cell.

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20
Q

What antibodies are involved in complement activation?

A

IgM and IgG

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21
Q

What are the 5 classes of antibody/immunoglobulin?

A

IgG, IgA, IgM, IgE, IgD

22
Q

Is IgG a monomer, dimer or pentamer?

A

Monomer

23
Q

Is IgA a monomer, dimer or pentamer?

A

dimer

24
Q

Is IgM a monomer, dimer or pentamer?

A

pentamer

25
Q

Is IgE a monomer, dimer or pentamer?

A

Monomer

26
Q

Is IgD a monomer, dimer or pentamer?

A

Monomer

27
Q

How many isotypes of immunoglobulin are there?

A

5

28
Q

What is the most abundant class of antibody in the blood?

A

IgG

29
Q

What are the functions of IgG?

A

Opsonisation, neutralisation, virus/bacteria targeting, passive immunity via placenta

30
Q

What antibodies are conferred to a foetus and then infant, via passive immunity?

A

IgG and IgA

31
Q

What is IgA found in?

A

Secretions such as tears, saliva, mucus and breast milk

32
Q

In what form is IgA found in the blood?

A

Monomeric

33
Q

What are the functions of IgA?

A

Defence of mucous membranes, passive immunity to nursing infants via breast milk

34
Q

What is IgM?

A

A pentamer antibody expressed on naïve B cells as the first antibody produced after initial exposure to an antigen.

35
Q

What is the first class of antibody produced after initial exposure to an antigen?

A

IgM

36
Q

What are thee functions of IgM?

A

Activates complement, targets extracellular bacteria with toxicity and neutralisation, acts as antigen receptor (BCR)

37
Q

What is IgE?

A

A monomeric antigen, present in blood at very low concentrations

38
Q

What are the functions of IgE?

A

Immunity to multicellular parasites, allergic reactions

39
Q

What is IgD?

A

A monomeric antigen, expressed on naïve B cells.

40
Q

What is the function of IgD?

A

acts as an antigen receptor (BCR)

41
Q

What antigen is most important in the secondary immune response?

A

IgG

42
Q

When B cells are stimulated by antigen and T cells, what are formed?

A

Plasma B cells and memory B cells.

43
Q

What are memory B cells?

A

B cells that express antibody as BCR, but cannot secrete antibodies until retriggered by antigen, at which stage they develop rapidly into plasma cells. They can persist for years in tissue until needed.

44
Q

What is the primary immune response, in terms of B cells?

A

When the body is first exposed to an antigen, naïve B cells are activated, producing plasma and memory B cells. It takes a long time for sufficient antibodies to build up to eliminate a pathogen.

45
Q

How long does it a take for sufficient antibody to be secreted in a primary immune response?

A

7-14 days

46
Q

What are the relative levels of antibody produced in the primary immune response?

A

relatively low levels of IgM antibody

47
Q

What is the predominant type of antibody produced in the primary immune response?

A

IgM

48
Q

What is the secondary immune response, in terms of B cells?

A

When antigens are detected by memory B cells, which will then form plasma cells and secrete antibodies.

49
Q

What antibodies are produced in low levels, due to class switching, in the secondary immune response?

A

IgA and IgE (class switching with IgG)

50
Q

How long does it take for sufficient antibodies to be produced in the secondary immune response?

A

2-3 days

51
Q

What are the relative levels of antibody in the secondary immune response, compared to primary?

A

Much higher

52
Q

Why is the rate of antibody response in the secondary immune response faster than in the primary immune response?

A

Because it is quicker for memory B cells to form secretory plasma cells than for naïve B cells.

HUBS191 (36 decks)

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