Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BDS1 Pathology > Adaptive Immunity - B cells > Flashcards

Adaptive Immunity - B cells Flashcards

1
Q

Where do B cells mature?

A

In the bone marrow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Where are B cells found?

A

Circulate in the blood and the lymph and are found in large numbers in lymphoid organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do B cells recognise antigens?

A

Through B cell receptors which are the actual antibodies against the antigen they respond to (IgM or IgD)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does ‘diversity’ in BCR mean?

A

They have the potential to respond to numerous antigens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Once activated what do B cells change into?

A

Plasma cells which churn out lots of antibodies against that specific antigen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the 3 main molecules that are involved in recognition of foreign antigen by adaptive immune system?

A
  • T cell receptor
  • B cell receptor (Immunoglobins)
  • Major histocompatibility complex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What allows the development of a repertoire of receptors with specificity for wide ranges of antigens?

A

Multiple genes encoding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What 2 chains are immunoglobins made up of?

A

A heavy chain and a light chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What 2 regions are present in immunoglobins?

A

A constant region and a variable region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What shape is an immunoglobin?

A

Y-shaped

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What region in immunoglobins is the region that changes between antibodies?

A

The variable region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does the springy section of immunoglobins allow them to do?

A

lets it bind with other molecules and cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How many different classes of immunoglobins are there?

A

5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the main antibody functions?

A
  • Neutralisation - antibody can bind to and stop from working
  • Opsonisation - main function - Stick to surface of microbe
  • Complement activation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the main components of opsonization?

A
  • Opsonized phagocytosis (IgG)
  • ADCC (NK cell-mediated killing) (IgG)
  • Mast cell degranulation (IgE)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is each development stage of B cell development defined by?

A

Rearrangements of the immunoglobin heavy and light chain genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How do B cell receptors generate diversity?

A
  • Heavy chain involves rearrangement of Variable, Diversity and Joining genes
  • Light chain rearrangement of Variable and Joining genes
  • Binding site for antigen is in the variable region so cell can choose any combination of these genes to produce unique antibody binding sites
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

During B cell development what are the B cell receptors?

A
  • Immature B cell receptor is mainly IgM (mainly produce IgM not only on surface to act as receptor - they also release IgM)
  • IgM can be classed as early receptor but main receptor is IgD
  • Mature B cell express both IgM and IgD on surface
19
Q

What is negative selection in B cell development?

A
  • Like the TCR there is great diversity in the B cell receptor repertoire
  • Need to ensure that there is no reactivity against self antigens
  • Therefore in bone marrow as B cells are developing they undergo negative selection
20
Q

What is meant by mature B cells being antigen naïve?

A

Have not yet been exposed to a foreign antigen

21
Q

How can B cell activation occur in regards to T cells?

A

In a T cell dependent or independent manner

22
Q

Whether B cells are activated by T cells or not depends on the type of antigen. What are these antigens called?

A
  • Antigens which require T cell help are called thymus dependent antigens
  • Antigens that don’t require T cell help are called thymus-independent
23
Q

Where does B cell activation mainly occur?

A

In lymphoid organs such as lymph nodes

24
Q

Apart from lymphoid organs where can B cell activation occur?

A

Can get naïve B cells in periphery so some peripheral activation (particularly thymus-independent)

25
Q

What does the activation of naïve B cells result in?

A

The rise of plasma cells

- Plasma cells are antibody factories

26
Q

What is the process of thymus dependent B cell activation?

A
  • Interaction between T cell and BCR also requires co-receptor binding (CD40 and CD40L) to stabilise the interaction
  • Cytokine signals released from T helper cell induce proliferation
  • Generates a pool of plasma cells which produce antibody
  • Also generated memory B cells
  • Plasma cells initially produce IgM before undergoing ‘class switching’
27
Q

What is meant by the term ‘class switching’ in thymus dependent B cell activation?

A
  • Initially the plasma cells produce IgM which is quite effective, but not as effective as IgG
  • Eventually will stop producing IgM and will switch to IgG
  • IgM produce is specific for unique antigen and when switches to IgG is still specific for unique antigen - antigen binding site remains the same
28
Q

What does ‘affinity’ mean?

A

Strength of binding of single antibody to antigen

29
Q

What does ‘avidity’ mean?

A

Ability of antibodies to form complexes (antibody-antibody binding)

30
Q

How does antibody affinity and avidity increase towards antigen on secondary exposures?

A
  • IgM response is weak. Cells therefore class switch to IgG (or IgA/IgE)
  • Occurs by gene rearrangement but antigen binding site remains the same
  • Repeated exposure to antigen causes affinity maturation. The antibody has increasing affinity for the antigen which produces a stronger response
31
Q

What is the process of thymus independent B cell activation?

A
  • Certain antigens such as bacterial LPS can activate B cells directly
  • Cells differentiate into plasma cell and produce IgM however antibody response is weaker than TD B cell activation
  • TI B cell activation does not lead to the generation of memory B cells (no long term immunity)
32
Q

In lymphoid organs cross talk between B and T cells leads to generation of both arms of the adaptive immune response. What are the ‘two arms’ of the adaptive immune response?

A
  • Humoral Immunity
  • Cellular immunity
  • Peak of activity of immune response is when the body has B and T cells both working optimally
33
Q

What is the primary and secondary immune response?

A
  • Primary exposure to antigens leads to the development of memory - this is the primary immune response and takes time to develop
  • In the primary immune response IgM acts early but as B cells undergo class switching an IgG response follows
  • Due to the generation of memory T and B cells this means that upon a second exposure we have a pool of cells waiting to respond immediately so the response is immediate
  • In addition, we have cells that are primed to produce a more effective IgG (rather than IgM) response immediately
  • This is the basic principle of vaccination
34
Q

What is immunological tolerance?

A
  • A state of immune unresponsiveness to a particular antigen or set of antigens
  • Immunological tolerance is an active response to a particular epitope and is just as specific as an immune response
35
Q

Which cells can be made tolerant?

A

Both B and T cells - more important to tolerise T cells as B cells cannot make antibodies to most antigens without the help of T cells

36
Q

What are the 2 main types of tolerance depending on anatomical location?

A
  1. Central - occurs while developing immune cells are still present in the primary lymphoid organs (the thymus and the bone marrow), prior to export into the periphery
  2. Peripheral - occurs out with thymus and bone marrow
37
Q

Where does central tolerance T cells occur?

A

Occurs in the thymus

38
Q

What is the process of central tolerance T cells?

A
  • T cells have to bind to MHC molecules (but not too strongly). Those that bind with correct MHC binding survive (positive selection)
  • T cells must not bind to self-antigens. Those that do are eliminated (negative selection)
  • This process leads to elimination of over 90% of T cells
  • The rest emigrate to peripheral tissues and secondary lymphoid organs
  • However, not all self reactive T cells are eliminated
39
Q

Explain the process of peripheral tolerance T cells?

A
  • Not all self reactive T cells are eliminated centrally
  • However, peripheral tolerance prevents their action
  • T cell activation is a 3 signal process
  • Signal 1 but no signal 2 results in anergy. APC upregulates CD80/86 in response to TLR stimulation
  • Signal 1 and 2 but no 3 (cytokine survival signal) results in deletion by apoptosis
  • Treg’s can also directly block activity by binding to the antigen (both self and foreign)
40
Q

Where does central tolerance B cells occur?

A

In the bone marrow

41
Q

Explain the process of central tolerance B cells?

A
  • B cell central tolerance involves negative selection only

- Therefore B cells which bind strongly to self antigen are eliminated

42
Q

Where does peripheral tolerance in B cells occur?

A

In secondary lymphoid organs

43
Q

Explain the process of peripheral tolerance in B cells?

A
  • Self reactive B cells still require help from self reactive T cells
  • Since most self reactive T cells are eliminated, self reactive B cells do not receive T cell help and therefore become anergic
  • Having B and T cells that both respond to a specific self antigen is slim
44
Q

What des breach of tolerance to ‘self-antigens’ mean?

A

Autoimmune diseases occur where our body does attack self antigens
- A breach of tolerance mans there has been a breakdown in the process somewhere

BDS1 Pathology (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions