Lecture 6: B Lymphocyte Responses

Question 1

What are natural barriers to infectious pathogens?

Answer 1

Mechanical Chemical Microbiological

Question 2

What are the characteristics of innate immune system?

Answer 2

Evolutionary older Indiscriminate Immediate in action Manifests acute Inflammation

Question 3

What are the characteristics of adaptive immune system?

Answer 3

Evolutionary newer Very specific Late in action Develops memory

Question 4

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

Answer 4

APC T cells B cells

Question 5

Once a T cell is active what does it do ?

Answer 5

Activate B cells

Question 6

Where are B lymphocytes generated?

Answer 6

Bone marrow from hematopoietic stem cells

Question 7

What does pluripotent hematopoietic cell give rise to?

Answer 7

All of our blood cells

Question 8

What two types can pluripotent hematopoietic cell differentiate into?

Answer 8

Common lymphoid progenitor Common myeloid progenitor

Question 9

Where are B cells produced from?

Answer 9

Common lymphoid progenitor

Question 10

How are B cells differentiated?

Answer 10

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

Question 11

What do B cells differentiate into?

Answer 11

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

Question 12

What are the multiple stages of B lymphocytes?

Answer 12

Generation Development Maturation Activation Differentiation

Question 13

Why are series of genes upregulated/down regulated?

Answer 13

Generation and differentiation of cells that become B cells

Question 14

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

Answer 14

Secondary lymphoid organs

Question 15

What has the immune system evolved to provide ?

Answer 15

Filter in the bone marrow

Question 16

How are B cells that recognises self eliminated?

Answer 16

Apoptosis

Question 17

What does a single progenitor cell give rise to?

Answer 17

Large number of lymphocytes each with a different specificity

Question 18

How are self reactive immature lymphocytes eliminated?

Answer 18

Clonal deletion

Question 19

How are a clone of effector cells formed?

Answer 19

Proliferation and differentiation of activated specific lymphocytes

Question 20

Where are cytokines of B cells produced?

Answer 20

Stromal cells

Question 21

B-cell precursor rearranges it’s immunoglobulin genes

Answer 21

Generation of B cell receptors in the bone marrow

Question 22

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

Answer 22

Negative selection in bone marrow

Question 23

Mature B cell bound to foreign Antigen is activated

Answer 23

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

Question 24

Activated B cells give rise to memory and plasma cells

Answer 24

Antibody secretion and memory cells in bone marrow and lymphoid tissue

Question 25

How do B lymphocytes recognise antigens?

Answer 25

Through their membrane

Question 26

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

Answer 26

One

Question 27

What are Antigens?

Answer 27

Any structures recognised by antibodies

Question 28

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

Answer 28

Immunogenic

Question 29

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

Answer 29

Epitopes

Question 30

What are infectious pathogens?

Answer 30

Viruses Bacteria and their toxins Fungi Protozoa Helminths

Question 31

What are non-infectious agents?

Answer 31

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

Question 32

What can Antigens be?

Answer 32

Membrane bound, Intra-cellular or secreted by pathogens

Question 33

What is conformational epitope?

Answer 33

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

Question 34

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

Answer 34

Number of epitopes that are present on a given Antigen

Question 35

What do most antigens require?

Answer 35

T cell help

Question 36

What are the 2 additional molecules of B lymphocytes

Answer 36

Ig alpha and Ig beta

Question 37

What happens when an antibody encounters an Antigen?

Answer 37

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

Question 38

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

Answer 38

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

Question 39

what is the process of B cell activation?

Answer 39

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

Question 40

What is one feature of the adaptive system?

Answer 40

Development of immunological memory

Question 41

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

Answer 41

1 in 1000 B cells

Question 42

What is he main antibody present in blood?

Answer 42

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

Question 43

How does antibody affinity increase?

Answer 43

Exposure

Question 44

What does the antibody gene require?

Answer 44

Somatic hyper-mutation

Question 45

What are CH2 and CH3?

Answer 45

Binding of complement and phagocytic cells

Question 46

Why do antibodies have different Constant regions?

Answer 46

Distinguish antibodies into isotypes with different biological functions

Question 47

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

Answer 47

Surface of antibodies and involved in binding to antigen epitopes

Question 48

What is the structure of Antibodies? What

Answer 48

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

Question 49

Why is the Constant region important?

Answer 49

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

Question 50

Where are IgM produced?

Answer 50

Initial phases

Question 51

Where are IgD expressed?

Answer 51

Membrane

Question 52

Where are IgE present?

Answer 52

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

Question 53

Where are IgA expressed?

Answer 53

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

Question 54

How are variable region formed?

Answer 54

Combining small genes together

Question 55

How are the diversity of Antibodies generated?

Answer 55

Combinatorial diversity Junctional diversity Somatic mutations

Question 56

What is combinatorial diversity?

Answer 56

Rearrangement of different mini genes for different H and L chains

Question 57

What is junctional diversity?

Answer 57

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

Question 58

What does variable region gene recombination involve?

Answer 58

Lymphocyte-Specific and ubiquitous enzymes

Question 59

How are different amino acids generated?

Answer 59

Different cuttings and using of nucleotides at junctions between genes

Question 60

What is somatic mutation?

Answer 60

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

Question 61

What are the effector mechanisms when antibody binds to Antigens ?

Answer 61

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