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Immunology > Lecture 6: B Lymphocyte Responses > Flashcards

Lecture 6: B Lymphocyte Responses Flashcards

1
Q

What are natural barriers to infectious pathogens?

A

Mechanical Chemical Microbiological

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2
Q

What are the characteristics of innate immune system?

A

Evolutionary older Indiscriminate Immediate in action Manifests acute Inflammation

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3
Q

What are the characteristics of adaptive immune system?

A

Evolutionary newer Very specific Late in action Develops memory

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4
Q

What are the 3 cells the adaptive immune system consists of?

A

APC T cells B cells

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5
Q

Once a T cell is active what does it do ?

A

Activate B cells

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6
Q

Where are B lymphocytes generated?

A

Bone marrow from hematopoietic stem cells

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7
Q

What does pluripotent hematopoietic cell give rise to?

A

All of our blood cells

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8
Q

What two types can pluripotent hematopoietic cell differentiate into?

A

Common lymphoid progenitor Common myeloid progenitor

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9
Q

Where are B cells produced from?

A

Common lymphoid progenitor

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10
Q

How are B cells differentiated?

A

Under influence of cytokines produced by cells that exist in the bone marrow .

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11
Q

What do B cells differentiate into?

A

Pro B cells then pre B cells [they then rearrange their immunoglobulin]

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12
Q

What are the multiple stages of B lymphocytes?

A

Generation Development Maturation Activation Differentiation

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13
Q

Why are series of genes upregulated/down regulated?

A

Generation and differentiation of cells that become B cells

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14
Q

Where does the activation and maturation of B cells take place?

A

Secondary lymphoid organs

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15
Q

What has the immune system evolved to provide ?

A

Filter in the bone marrow

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16
Q

How are B cells that recognises self eliminated?

A

Apoptosis

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17
Q

What does a single progenitor cell give rise to?

A

Large number of lymphocytes each with a different specificity

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18
Q

How are self reactive immature lymphocytes eliminated?

A

Clonal deletion

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19
Q

How are a clone of effector cells formed?

A

Proliferation and differentiation of activated specific lymphocytes

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20
Q

Where are cytokines of B cells produced?

A

Stromal cells

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21
Q

B-cell precursor rearranges it’s immunoglobulin genes

A

Generation of B cell receptors in the bone marrow

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22
Q

Immature B cells bound to self cell-surface Antigen is removed from the repertoire

A

Negative selection in bone marrow

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23
Q

Mature B cell bound to foreign Antigen is activated

A

Migration of B cells through the circulatory system to lymphoid organs and B cell activation

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24
Q

Activated B cells give rise to memory and plasma cells

A

Antibody secretion and memory cells in bone marrow and lymphoid tissue

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25
Q

How do B lymphocytes recognise antigens?

A

Through their membrane

26
Q

A B cell has how many messenger MRNA for an antibody?

A

One

27
Q

What are Antigens?

A

Any structures recognised by antibodies

28
Q

An Antigen is said to be what when it can stimulate an immune response?

A

Immunogenic

29
Q

What are antibodies that can recognise distinct parts of antigen called ?

A

Epitopes

30
Q

What are infectious pathogens?

A

Viruses Bacteria and their toxins Fungi Protozoa Helminths

31
Q

What are non-infectious agents?

A

Normal self proteins Cancer proteins Pollen Transported allo or xeno grafts Chemicals e.g. some drugs

32
Q

What can Antigens be?

A

Membrane bound, Intra-cellular or secreted by pathogens

33
Q

What is conformational epitope?

A

Sequence of subunits composing of an Antigen that can come in direct contact with a receptor or the immune system

34
Q

What will dictate how many B cell clones you will have ?

A

Number of epitopes that are present on a given Antigen

35
Q

What do most antigens require?

A

T cell help

36
Q

What are the 2 additional molecules of B lymphocytes

A

Ig alpha and Ig beta

37
Q

What happens when an antibody encounters an Antigen?

A

Conformational changes within antibody molecule that leads to activation of signalling regions within Ig-alpha and Ig-beta

38
Q

What happens when the signalling regions of Ig-alpha and Ig-beta are activated?

A

Protein phosphorylation —> activate further molecules downstream from membrane —> go to nucleus to activate transcription factors

39
Q

what is the process of B cell activation?

A

Antigen recognition Induction of signalling Activation of transcription factors Expression of MRNA molecules to produce proteins that are necessary for function of B cells

40
Q

What is one feature of the adaptive system?

A

Development of immunological memory

41
Q

What is the frequency of B cell that can recognise an Antigen?

A

1 in 1000 B cells

42
Q

What is he main antibody present in blood?

A

IgG

Recognises antigen but also has a constant region for recruiting other molecules important for destruction of pathogens

43
Q

How does antibody affinity increase?

A

Exposure

44
Q

What does the antibody gene require?

A

Somatic hyper-mutation

45
Q

What are CH2 and CH3?

A

Binding of complement and phagocytic cells

46
Q

Why do antibodies have different Constant regions?

A

Distinguish antibodies into isotypes with different biological functions

47
Q

Where are hypervariable regions exposed and what are they involved in?

A

Surface of antibodies and involved in binding to antigen epitopes

48
Q

What is the structure of Antibodies? What

A

Composed of 2 chains [light and heavy chains] Each chain is a domain consisting of 110 amino acids Molecular weight of 12 1/2 thousand Variable region is different from one B cell to next

49
Q

Why is the Constant region important?

A

It has areas where it can bind to receptors on the surface of macrophages

50
Q

Where are IgM produced?

A

Initial phases

51
Q

Where are IgD expressed?

A

Membrane

52
Q

Where are IgE present?

A

Skins and membrane
which are exposed to parasites
Mouth, throat, stomach, lungs

53
Q

Where are IgA expressed?

A

Gut (important for protecting mucosal membrane)
Not easily digested by enzymes
Don’t activate the complement system to induce inflammation

54
Q

How are variable region formed?

A

Combining small genes together

55
Q

How are the diversity of Antibodies generated?

A

Combinatorial diversity Junctional diversity Somatic mutations

56
Q

What is combinatorial diversity?

A

Rearrangement of different mini genes for different H and L chains

57
Q

What is junctional diversity?

A

Imprecise V (D) J joining P additions N additions D-D fusions

58
Q

What does variable region gene recombination involve?

A

Lymphocyte-Specific and ubiquitous enzymes

59
Q

How are different amino acids generated?

A

Different cuttings and using of nucleotides at junctions between genes

60
Q

What is somatic mutation?

A

Replaces existing amino acids in the Ag variable region to increase antibody affinity

61
Q

What are the effector mechanisms when antibody binds to Antigens ?

A
  1. Antibodies neutralise antigens or promote their destruction by phagocytosis or the complement system. 2. Antibodies also bind F.C. receptor and induce the activation of other immune cells such as mast cells 3. Antibodies bind antigens on target or infected cells and promote destruction by NK cells 4. B cells capture antigens by their membrane antibodies and activate T lymphocyte and induce cytokine production

Immunology (20 decks)

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