Adaptive Immunity 1 Flashcards
1
Q
Why do we need an adaptive immune system?
A
Capacity to learn from and remebmber different pathogens - can provide long lasting defence and protection against recurrent infections - when exposed to a new threat they are remembered, if exposed again response is quicker and more effective
2
Q
The Immune Response - First & Second Line of Defence
- The first line of defence against pathogens is the … immune response (non-specific) - this consists of physical, chemical and cellular defence mechanisms against pathogens. Main purpose - prevent spread
- Second line of defence against pathogens is the … immune response (acquired, specific) - specific to every pathogen we encounter. Orchestrated by lymphocytes - supposed to only attack non-self pathogens but can sometimes lead to errors (recognising self) - autoimmune diseases can develop
A
- The first line of defence against pathogens is the innate immune response (non-specific) - this consists of physical, chemical and cellular defence mechanisms against pathogens. Main purpose - prevent spread
- Second line of defence against pathogens is the adaptive immune response (acquired, specific) - specific to every pathogen we encounter. Orchestrated by lymphocytes - supposed to only attack non-self pathogens but can sometimes lead to errors (recognising self) - autoimmune diseases can develop
3
Q
The Immune Response - First & Second Line of Defence
- The first line of defence against pathogens is the innate immune response (…-…) - this consists of physical, chemical and cellular defence mechanisms against pathogens. Main purpose - prevent spread
- Second line of defence against pathogens is the adaptive immune response (…, …) - specific to every pathogen we encounter. Orchestrated by lymphocytes - supposed to only attack non-self pathogens but can sometimes lead to errors (recognising self) - autoimmune diseases can develop
A
- The first line of defence against pathogens is the innate immune response (non-specific) - this consists of physical, chemical and cellular defence mechanisms against pathogens. Main purpose - prevent spread
- Second line of defence against pathogens is the adaptive immune response (acquired, specific) - specific to every pathogen we encounter. Orchestrated by lymphocytes - supposed to only attack non-self pathogens but can sometimes lead to errors (recognising self) - autoimmune diseases can develop
4
Q
The Immune Response - First & Second Line of Defence
- The first line of defence against pathogens is the innate immune response (non-specific) - this consists of physical, chemical and cellular defence mechanisms against pathogens. Main purpose - prevent …
- Second line of defence against pathogens is the adaptive immune response (acquired, specific) - specific to every pathogen we encounter. Orchestrated by … - supposed to only attack non-self pathogens but can sometimes lead to errors (recognising self) - … diseases can develop
A
- The first line of defence against pathogens is the innate immune response (non-specific) - this consists of physical, chemical and cellular defence mechanisms against pathogens. Main purpose - prevent spread
- Second line of defence against pathogens is the adaptive immune response (acquired, specific) - specific to every pathogen we encounter. Orchestrated by lymphocytes - supposed to only attack non-self pathogens but can sometimes lead to errors (recognising self) - autoimmune diseases can develop
5
Q
Adaptive immunity is orchestrated by …
A
lymphocytes
6
Q
Recognition of lymphocyte subsets
- All lymphocytes originate from a … stem cell in the … …
- RHS - all lymphocytes are derived from common lymphoid progenitor cell
- 3 options from here - B Cell, T cell, NK cell (hard to distinguish through a microscope - identified by unique proteins identified on cell surface)
A
- All lymphocytes originate from a pluripotent stem cell in bone marrow
- RHS - all lymphocytes are derived from common lymphoid progenitor cell
- 3 options from here - B Cell, T cell, NK cell (hard to distinguish through a microscope - identified by unique proteins identified on cell surface)
7
Q
Recognition of lymphocyte subsets
- All lymphocytes originate from a pluripotent stem cell in the bone marrow
- RHS - all lymphocytes are derived from common lymphoid progenitor cell
- 3 options from here - … cell, … cell, … cell (hard to distinguish through a microscope - identified by unique proteins identified on cell surface)
A
- All lymphocytes originate from a pluripotent stem cell in bone marrow
- RHS - all lymphocytes are derived from common lymphoid progenitor cell
- 3 options from here - B Cell, T cell, NK cell (hard to distinguish through a microscope - identified by unique proteins identified on cell surface)
8
Q
Recognition of lymphocyte subsets
- All lymphocytes originate from a pluripotent stem cell in the … …
- RHS - all lymphocytes are derived from common … … cell
- 3 options from here - B Cell, T cell, NK cell (hard to distinguish through a microscope - identified by unique proteins identified on cell surface)
A
- All lymphocytes originate from a pluripotent stem cell in bone marrow
- RHS - all lymphocytes are derived from common lymphoid progenitor cell
- 3 options from here - B Cell, T cell, NK cell (hard to distinguish through a microscope - identified by unique proteins identified on cell surface)
9
Q
Recognition of lymphocyte subsets - 2
- All B cells apart from terminally differentiated plasma cells express a protein on surface called CD19
- All T cells express CD3
- Further subdivided (… - Helper T cells or … - Cytotoxic T cells)
A
- All B cells apart from terminally differentiated plasma cells express a protein on surface called CD19
- All T cells express CD3
- Further subdivided (CD4 - Helper T cells or CD8 - Cytotoxic T cells)
10
Q
Recognition of lymphocyte subsets - 2
- All B cells apart from terminally differentiated plasma cells express a protein on surface called …
- All T cells express CD3
- Further subdivided (CD4 - Helper T cells or CD8 - Cytotoxic T cells)
A
- All B cells apart from terminally differentiated plasma cells express a protein on surface called CD19
- All T cells express CD3
- Further subdivided (CD4 - Helper T cells or CD8 - Cytotoxic T cells)
11
Q
Recognition of lymphocyte subsets - 2
- All B cells apart from terminally differentiated plasma cells express a protein on surface called CD19
- All T cells express …
- Further subdivided (CD4 - Helper T cells or CD8 - Cytotoxic T cells)
A
- All B cells apart from terminally differentiated plasma cells express a protein on surface called CD19
- All T cells express CD3
- Further subdivided (CD4 - Helper T cells or CD8 - Cytotoxic T cells)
12
Q
Recognition of lymphocyte subsets - 2
- All B cells apart from terminally differentiated plasma cells express a protein on surface called CD19
- All T cells express CD3
- Further subdivided (CD4 - … T cells or CD8 - … T cells)
A
- All B cells apart from terminally differentiated plasma cells express a protein on surface called CD19
- All T cells express CD3
- Further subdivided (CD4 - Helper T cells or CD8 - Cytotoxic T cells)
13
Q
T cell differentiation
- T cell precursors originate in the bone marrow but then migrate to the … where they undergo maturation into either CD4 or CD8 cells.
- The CD4 T helper cells can be further sub-divided according to the cytokines that they produce, into Th1, Th2, Th17 and regulatory T cells.
A
- T cell precursors originate in the bone marrow but then migrate to the thymus where they undergo maturation into either CD4 or CD8 cells.
- The CD4 T helper cells can be further sub-divided according to the cytokines that they produce, into Th1, Th2, Th17 and regulatory T cells.
14
Q
T cell differentiation
- T cell precursors originate in the bone marrow but then migrate to the thymus where they undergo maturation into either … or … cells.
- The CD4 T helper cells can be further sub-divided according to the cytokines that they produce, into Th1, Th2, Th17 and regulatory T cells.
A
- T cell precursors originate in the bone marrow but then migrate to the thymus where they undergo maturation into either CD4 or CD8 cells.
- The CD4 T helper cells can be further sub-divided according to the cytokines that they produce, into Th1, Th2, Th17 and regulatory T cells.
15
Q
T cell differentiation
- T cell precursors originate in the bone marrow but then migrate to the thymus where they undergo maturation into either CD4 or CD8 cells.
- The CD4 T helper cells can be further sub-divided according to the cytokines that they produce, into Th.., Th.., Th17 and regulatory T cells.
A
- T cell precursors originate in the bone marrow but then migrate to the thymus where they undergo maturation into either CD4 or CD8 cells.
- The CD4 T helper cells can be further sub-divided according to the cytokines that they produce, into Th1, Th2, Th17 and regulatory T cells.
16
Q
T cell differentiation
- T cell precursors originate in the bone marrow but then migrate to the thymus where they undergo maturation into either CD4 or CD8 cells.
- The CD4 T helper cells can be further sub-divided according to the cytokines that they produce, into Th1, Th2, Th… and … T cells.
A
- T cell precursors originate in the bone marrow but then migrate to the thymus where they undergo maturation into either CD4 or CD8 cells.
- The CD4 T helper cells can be further sub-divided according to the cytokines that they produce, into Th1, Th2, Th17 and regulatory T cells.
17
Q
… T helper cells can be further sub-divided according to the cytokines that they produce, into Th1, Th2, Th17 and regulatory T cells.
A
CD4 T helper cells can be further sub-divided according to the cytokines that they produce, into Th1, Th2, Th17 and regulatory T cells.
18
Q
CD4 T helper cells can be further sub-divided according to the cytokines that they produce, into Th…, Th…, Th… and regulatory T cells.
A
CD4 T helper cells can be further sub-divided according to the cytokines that they produce, into Th1, Th2, Th17 and regulatory T cells.
19
Q
CD4 T helper cells can be further sub-divided according to the cytokines that they produce, into … (4)
A
CD4 T helper cells can be further sub-divided according to the cytokines that they produce, into Th1, Th2, Th17 and regulatory T cells.
20
Q
B and T cell development
- Both B and T cell development is guided by … cells
- B cells - entirely by … cells in the bone marrow
- T cells - development is compartmentalised - cortex and medulla of the thymus
A
- Both B and T cell development is guided by stromal cells
- B cells - entirely by stromal cells in the bone marrow
- T cells - development is compartmentalised - cortex and medulla of the thymus
21
Q
B and T cell development
- Both B and T cell development is guided by stromal cells
- B cells - entirely by stromal cells in the bone marrow
- T cells - development is … - cortex and medulla of the thymus
A
- Both B and T cell development is guided by stromal cells
- B cells - entirely by stromal cells in the bone marrow
- T cells - development is compartmentalised - cortex and medulla of the thymus
22
Q
Both B and T cell development is guided by … cells
A
Both B and T cell development is guided by stromal cells
23
Q
B and T cells both involve cell death via …
A
B and T cells both involve cell death via apoptosis
24
Q
Comparison of B cell and T cell development
- B cells are produced throughout life in the bone marrow (-… new B cells every day) - … days life expectancy
- T cells are produced in the thymus which involutes at the end of puberty - but thymus in adults does have some residiual corticomedullary tissue and new T cells are also generated in extrathymic sites (liver and intestine) - also very long lived - 4x10(^11) circulating T cells
- Both have diverse repertoires of antigen receptors - generated by genetic rearrangements
A
- B cells are produced throughout life in the bone marrow (-50million new B cells every day) - 5 days life expectancy
- T cells are produced in the thymus which involutes at the end of puberty - but thymus in adults does have some residiual corticomedullary tissue and new T cells are also generated in extrathymic sites (liver and intestine) - also very long lived - 4x10(^11) circulating T cells
- Both have diverse repertoires of antigen receptors - generated by genetic rearrangements
25
Q
Comparison of B cell and T cell development
- B cells are produced throughout life in the bone marrow (-50million new B cells every day) - 5 days life expectancy
- T cells are produced in the thymus which involutes at the end of … - but thymus in adults does have some residiual … tissue and new T cells are also generated in extrathymic sites (liver and intestine) - also very long lived - 4x10(^11) circulating T cells
- Both have diverse repertoires of antigen receptors - generated by genetic rearrangements
A
- B cells are produced throughout life in the bone marrow (-50million new B cells every day)
- T cells are produced in the thymus which involutes at the end of puberty - but thymus in adults does have some residiual corticomedullary tissue and new T cells are also generated in extrathymic sites (liver and intestine) - also very long lived - 4x10(^11) circulating T cells
- Both have diverse repertoires of antigen receptors - generated by genetic rearrangements
26
Q
Comparison of B cell and T cell development
- B cells are produced throughout life in the bone marrow (-50million new B cells every day) - 5 days life expectancy
- T cells are produced in the thymus which involutes at the end of puberty - but thymus in adults does have some residiual corticomedullary tissue and new T cells are also generated in extrathymic sites (… and …) - also very long lived - 4x10(^11) circulating T cells
- Both have diverse repertoires of antigen receptors - generated by genetic rearrangements
A
- B cells are produced throughout life in the bone marrow (-50million new B cells every day)
- T cells are produced in the thymus which involutes at the end of puberty - but thymus in adults does have some residiual corticomedullary tissue and new T cells are also generated in extrathymic sites (liver and intestine) - also very long lived - 4x10(^11) circulating T cells
- Both have diverse repertoires of antigen receptors - generated by genetic rearrangements
27
Q
Comparison of B cell and T cell development
- B cells are produced throughout life in the bone marrow (-50million new B cells every day) - 5 days life expectancy
- T cells are produced in the thymus which involutes at the end of puberty - but thymus in adults does have some residiual corticomedullary tissue and new T cells are also generated in extrathymic sites (liver and intestine) - also very long lived - 4x10(^11) circulating T cells
- Both have diverse repertoires of … … - generated by genetic rearrangements
A
- B cells are produced throughout life in the bone marrow (-50million new B cells every day)
- T cells are produced in the thymus which involutes at the end of puberty - but thymus in adults does have some residiual corticomedullary tissue and new T cells are also generated in extrathymic sites (liver and intestine) - also very long lived - 4x10(^11) circulating T cells
- Both have diverse repertoires of antigen receptors - generated by genetic rearrangements
28
Q
Lymphocyte stages of development - B cells
- These cells, just like T cells, originate from a common lymphoid progenitor in the bone marrow. The first evidence for commitment to becoming a B cell is the emergence of a …-B cell, which has undergone genetic rearrangement of its … (D) and … (J) segments.
- There then follows differentiation to pre-B cells (large then small) and the first expression of a pre B cell receptor on the cell surface. Immature B cells then undergo a process of positive and negative selection – only those B cells that are positively selected and avoid negative selection are finally released into the peripheral blood.
- Failure at either of these steps leads to apoptosis or programmed cell death.
A
- These cells, just like T cells, originate from a common lymphoid progenitor in the bone marrow. The first evidence for commitment to becoming a B cell is the emergence of a pro-B cell, which has undergone genetic rearrangement of its diversity (D) and joining (J) segments.
- There then follows differentiation to pre-B cells (large then small) and the first expression of a pre B cell receptor on the cell surface. Immature B cells then undergo a process of positive and negative selection – only those B cells that are positively selected and avoid negative selection are finally released into the peripheral blood.
- Failure at either of these steps leads to apoptosis or programmed cell death.
29
Q
Lymphocyte stages of development - B cells
- These cells, just like T cells, originate from a common lymphoid progenitor in the bone marrow. The first evidence for commitment to becoming a B cell is the emergence of a pro-B cell, which has undergone genetic rearrangement of its diversity (D) and joining (J) segments.
- There then follows differentiation to …-B cells (large then small) and the first expression of a … B cell receptor on the cell surface. Immature B cells then undergo a process of positive and negative selection – only those B cells that are positively selected and avoid negative selection are finally released into the peripheral blood.
- Failure at either of these steps leads to apoptosis or programmed cell death.
A
- These cells, just like T cells, originate from a common lymphoid progenitor in the bone marrow. The first evidence for commitment to becoming a B cell is the emergence of a pro-B cell, which has undergone genetic rearrangement of its diversity (D) and joining (J) segments.
- There then follows differentiation to pre-B cells (large then small) and the first expression of a pre B cell receptor on the cell surface. Immature B cells then undergo a process of positive and negative selection – only those B cells that are positively selected and avoid negative selection are finally released into the peripheral blood.
- Failure at either of these steps leads to apoptosis or programmed cell death.
30
Q
Lymphocyte stages of development - B cells
- These cells, just like T cells, originate from a common lymphoid progenitor in the bone marrow. The first evidence for commitment to becoming a B cell is the emergence of a pro-B cell, which has undergone genetic rearrangement of its diversity (D) and joining (J) segments.
- There then follows differentiation to pre-B cells (large then small) and the first expression of a pre B cell receptor on the cell surface. Immature B cells then undergo a process of … and … selection – only those B cells that are … selected and avoid … selection are finally released into the peripheral blood.
- Failure at either of these steps leads to apoptosis or programmed cell death.
A
- These cells, just like T cells, originate from a common lymphoid progenitor in the bone marrow. The first evidence for commitment to becoming a B cell is the emergence of a pro-B cell, which has undergone genetic rearrangement of its diversity (D) and joining (J) segments.
- There then follows differentiation to pre-B cells (large then small) and the first expression of a pre B cell receptor on the cell surface. Immature B cells then undergo a process of positive and negative selection – only those B cells that are positively selected and avoid negative selection are finally released into the peripheral blood.
- Failure at either of these steps leads to apoptosis or programmed cell death.
31
Q
Lymphocyte stages of development - B cells
- These cells, just like T cells, originate from a common lymphoid progenitor in the bone marrow. The first evidence for commitment to becoming a B cell is the emergence of a pro-B cell, which has undergone genetic rearrangement of its diversity (D) and joining (J) segments.
- There then follows differentiation to pre-B cells (large then small) and the first expression of a pre B cell receptor on the cell surface. Immature B cells then undergo a process of positive and negative selection – only those B cells that are positively selected and avoid negative selection are finally released into the peripheral blood.
- Failure at either of these steps leads to … or … cell death.
A
- These cells, just like T cells, originate from a common lymphoid progenitor in the bone marrow. The first evidence for commitment to becoming a B cell is the emergence of a pro-B cell, which has undergone genetic rearrangement of its diversity (D) and joining (J) segments.
- There then follows differentiation to pre-B cells (large then small) and the first expression of a pre B cell receptor on the cell surface. Immature B cells then undergo a process of positive and negative selection – only those B cells that are positively selected and avoid negative selection are finally released into the peripheral blood.
- Failure at either of these steps leads to apoptosis or programmed cell death.
32
Q
Lymphocyte stages of development - T cells
- For T cells, the T cell precursors migrate to the thymus where they undergo four different stages of … differentiation.
- … stands for … … and this signifies that these cells express neither CD4 nor CD8. DN4 cells express a pre T cell receptor and then transiently go through an immature single positive phase before becoming double positive for CD4 and CD8.
- These cells, like immature B cells, undergo both positive and negative selection before being released into the peripheral blood as either CD4 or CD8 T cells.
A
- For T cells, the T cell precursors migrate to the thymus where they undergo four different stages of DN differentiation.
- DN stands for double negative and this signifies that these cells express neither CD4 nor CD8. DN4 cells express a pre T cell receptor and then transiently go through an immature single positive phase before becoming double positive for CD4 and CD8.
- These cells, like immature B cells, undergo both positive and negative selection before being released into the peripheral blood as either CD4 or CD8 T cells.
33
Q
Lymphocyte stages of development - T cells
- For T cells, the T cell precursors migrate to the thymus where they undergo four different stages of DN differentiation.
- DN stands for double negative and this signifies that these cells express neither … nor …. DN4 cells express a pre T cell receptor and then transiently go through an immature single positive phase before becoming double positive for … and ….
- These cells, like immature B cells, undergo both positive and negative selection before being released into the peripheral blood as either … or … T cells.
A
- For T cells, the T cell precursors migrate to the thymus where they undergo four different stages of DN differentiation.
- DN stands for double negative and this signifies that these cells express neither CD4 nor CD8. DN4 cells express a pre T cell receptor and then transiently go through an immature single positive phase before becoming double positive for CD4 and CD8.
- These cells, like immature B cells, undergo both positive and negative selection before being released into the peripheral blood as either CD4 or CD8 T cells.
34
Q
Lymphocyte stages of development - T cells
- For T cells, the T cell precursors migrate to the thymus where they undergo four different stages of DN differentiation.
- DN stands for double negative and this signifies that these cells express neither CD4 nor CD8. … cells express a pre T cell receptor and then transiently go through an immature single positive phase before becoming double positive for CD4 and CD8.
- These cells, like immature B cells, undergo both positive and negative selection before being released into the peripheral blood as either CD4 or CD8 T cells.
A
- For T cells, the T cell precursors migrate to the thymus where they undergo four different stages of DN differentiation.
- DN stands for double negative and this signifies that these cells express neither CD4 nor CD8. DN4 cells express a pre T cell receptor and then transiently go through an immature single positive phase before becoming double positive for CD4 and CD8.
- These cells, like immature B cells, undergo both positive and negative selection before being released into the peripheral blood as either CD4 or CD8 T cells.
35
Q
Lymphocyte stages of development - T cells
- For T cells, the T cell precursors migrate to the thymus where they undergo four different stages of DN differentiation.
- DN stands for double negative and this signifies that these cells express neither CD4 nor CD8. DN4 cells express a pre T cell receptor and then transiently go through an immature single positive phase before becoming double positive for CD4 and CD8.
- These cells, like immature B cells, undergo both … and … selection before being released into the peripheral blood as either CD4 or CD8 T cells.
A
- For T cells, the T cell precursors migrate to the thymus where they undergo four different stages of DN differentiation.
- DN stands for double negative and this signifies that these cells express neither CD4 nor CD8. DN4 cells express a pre T cell receptor and then transiently go through an immature single positive phase before becoming double positive for CD4 and CD8.
- These cells, like immature B cells, undergo both positive and negative selection before being released into the peripheral blood as either CD4 or CD8 T cells.
36
Q
Common stages of B and T cell development
- We can summarise the common stages of B and T cell development into three separate phases:
- 1st phase is the generation of a unique antigen receptor through genetic rearrangement of the V (…) and … segments.
- The 2nd phase involves the … of the antigen receptor repertoire. The receptor is first challenged with self antigen and only those cells that recognize “self” are selected for further development. (Positive selection). Those receptors that bind too strongly to self antigen are then deleted (negative selection). So, how much self recognition is too much? You can imagine that release of a cell that recognizes self a little too much may be the basis of autoimmune problems.
- The 3rd phase involves encounter with foreign antigen. This phase takes place in the secondary lymphoid tissues (lymph nodes or spleen) and results in clonal selection and expansion – ultimately leading to the development of effector and memory lymphocytes.
A
- We can summarise the common stages of B and T cell development into three separate phases:
- 1st phase is the generation of a unique antigen receptor through genetic rearrangement of the V (D) and J segments.
- The 2nd phase involves the refinement of the antigen receptor repertoire. The receptor is first challenged with self antigen and only those cells that recognize “self” are selected for further development. (Positive selection). Those receptors that bind too strongly to self antigen are then deleted (negative selection). So, how much self recognition is too much? You can imagine that release of a cell that recognizes self a little too much may be the basis of autoimmune problems.
- The 3rd phase involves encounter with foreign antigen. This phase takes place in the secondary lymphoid tissues (lymph nodes or spleen) and results in clonal selection and expansion – ultimately leading to the development of effector and memory lymphocytes.
37
Q
Common stages of B and T cell development
- We can summarise the common stages of B and T cell development into three separate phases:
- 1st phase is the generation of a unique antigen receptor through genetic rearrangement of the V (D) and J segments.
- The 2nd phase involves the refinement of the antigen receptor repertoire. The receptor is first challenged with self antigen and only those cells that recognize “self” are selected for further development. (… selection). Those receptors that bind too strongly to self antigen are then deleted (… selection). So, how much self recognition is too much? You can imagine that release of a cell that recognizes self a little too much may be the basis of autoimmune problems.
- The 3rd phase involves encounter with foreign antigen. This phase takes place in the … lymphoid tissues (lymph nodes or spleen) and results in clonal selection and expansion – ultimately leading to the development of effector and memory lymphocytes.
A
- We can summarise the common stages of B and T cell development into three separate phases:
- 1st phase is the generation of a unique antigen receptor through genetic rearrangement of the V (D) and J segments.
- The 2nd phase involves the refinement of the antigen receptor repertoire. The receptor is first challenged with self antigen and only those cells that recognize “self” are selected for further development. (Positive selection). Those receptors that bind too strongly to self antigen are then deleted (negative selection). So, how much self recognition is too much? You can imagine that release of a cell that recognizes self a little too much may be the basis of autoimmune problems.
- The 3rd phase involves encounter with foreign antigen. This phase takes place in the secondary lymphoid tissues (lymph nodes or spleen) and results in clonal selection and expansion – ultimately leading to the development of effector and memory lymphocytes.
38
Q
Common Stages of B and T cell Development - 1st Phase
- 1st phase: generation of an … receptor
- V(…) … gene rearrangement – producing a new … receptor
A
- 1st phase: generation of an antigen receptor
- V(D) J gene rearrangement – producing a new antigen receptor
39
Q
Common Stages of B and T cell Development - 1st Phase
- 1st phase: generation of an antigen receptor
- V(D) J gene … – producing a new antigen receptor
A
- 1st phase: generation of an antigen receptor
- V(D) J gene rearrangement – producing a new antigen receptor
50
Q
B cell Antigens
- B cells, unlike T cells, can recognize native antigen and in some instances can produce a full immunological response against the pathogen without the need for T cell help. However, for the majority of antigens, B cells need to interact with T cells in order to become fully activated.
- The two different classes of antigen therefore are described as ’… independent’ and ‘… dependent’.
- …-independent antigens are classically polysaccharides, lipids or nucleic acids and are characterised by repeating motifs, which allow for B cell receptor cross-linking.
- The majority of antigens are proteins and are …-dependent antigens as they do not contain repeating epitopes.
A
- B cells, unlike T cells, can recognize native antigen and in some instances can produce a full immunological response against the pathogen without the need for T cell help. However, for the majority of antigens, B cells need to interact with T cells in order to become fully activated.
- The two different classes of antigen therefore are described as ’thymus independent’ and ‘thymus dependent’.
- T-independent antigens are classically polysaccharides, lipids or nucleic acids and are characterised by repeating motifs, which allow for B cell receptor cross-linking.
- The majority of antigens are proteins and are T-dependent antigens as they do not contain repeating epitopes.
51
Q
- For the majority of antigens, … cells need to interact with … cells in order to become fully activated.
- The two different classes of antigen therefore are described as ’thymus independent’ and ‘thymus dependent
A
- For the majority of antigens, B cells need to interact with T cells in order to become fully activated.
- The two different classes of antigen therefore are described as ’thymus independent’ and ‘thymus dependent
72
Q
T-independent and T-dependent B cell activation
- T-independent B cell activation follows a …-… activation model.
- T-dependent B cell activation also requires multiple signals – typically this would involve … cognate ligand/receptor interactions.
A
- T-independent B cell activation follows a 2-signal activation model.
- T-dependent B cell activation also requires multiple signals – typically this would involve three cognate ligand/receptor interactions.
73
Q
T-independent and T-dependent B cell activation
- T-independent B cell activation follows a 2-signal activation model.
- T-dependent B cell activation also requires multiple signals – typically this would involve three cognate ligand/receptor interactions.
A
- T-independent B cell activation follows a 2-signal activation model.
- T-dependent B cell activation also requires multiple signals – typically this would involve three cognate ligand/receptor interactions.
74
Q
B cell-T cell interactions
- For the vast majority of antigens, B cells need T cell help in order to produce an effective immune response.
- B cells and T cells have evolved an array of reciprocal ligand/receptor expression which allows them to interact with each other.
- Some of the most important are CD… and CD…ligand; CD80/CD86 and CD28.
A
- For the vast majority of antigens, B cells need T cell help in order to produce an effective immune response.
- B cells and T cells have evolved an array of reciprocal ligand/receptor expression which allows them to interact with each other.
- Some of the most important are CD40 and CD40ligand; CD80/CD86 and CD28.
78
Q
T-dependent B cell response
- T-dependent B cell responses requires a three-signal process:
- Sequence of events:
- Antigen binding to … provides “Signal 1” to B cell
- Antigen is internalised, processed and antigenic peptides are displayed on MHC for T cell recognition
- T… (… T-cell) recognises antigen-MHC complex via the T cell antigen receptor (TCR): provides “Signal 1” to T cell
- CD80/CD86 on B cell binding to CD28 on T cell provides “Signal 2” to T cell
- T cell activation leads to up-regulation of CD40L which bind to CD40 providing “Signal 2” to B cell
- Cytokine production by activated T cell also help to activate B cell…“Signal 3”
- B cell proliferates and differentiates into antibody secreting B cell (plasma cell) or becomes a memory B cell
- Sequence of events:
A
- T-dependent B cell responses requires a three-signal process:
- Sequence of events:
- Antigen binding to BCR provides “Signal 1” to B cell
- Antigen is internalised, processed and antigenic peptides are displayed on MHC for T cell recognition
- TH (helper T-cell) recognises antigen-MHC complex via the T cell antigen receptor (TCR): provides “Signal 1” to T cell
- CD80/CD86 on B cell binding to CD28 on T cell provides “Signal 2” to T cell
- T cell activation leads to up-regulation of CD40L which bind to CD40 providing “Signal 2” to B cell
- Cytokine production by activated T cell also help to activate B cell…“Signal 3”
- B cell proliferates and differentiates into antibody secreting B cell (plasma cell) or becomes a memory B cell
- Sequence of events:
79
Q
T-dependent B cell response
- T-dependent B cell responses requires a three-signal process:
- Sequence of events:
- Antigen binding to BCR provides “Signal 1” to B cell
- Antigen is internalised, processed and antigenic peptides are displayed on MHC for T cell recognition
- TH (helper T-cell) recognises antigen-MHC complex via the T cell antigen receptor (TCR): provides “Signal 1” to T cell
- CD…/CD… on B cell binding to CD28 on T cell provides “Signal 2” to T cell
- T cell activation leads to up-regulation of CD40L which bind to CD40 providing “Signal 2” to B cell
- … production by activated T cell also help to activate B cell…“Signal 3”
- B cell proliferates and differentiates into antibody secreting B cell (plasma cell) or becomes a memory B cell
- Sequence of events:
A
- T-dependent B cell responses requires a three-signal process:
- Sequence of events:
- Antigen binding to BCR provides “Signal 1” to B cell
- Antigen is internalised, processed and antigenic peptides are displayed on MHC for T cell recognition
- TH (helper T-cell) recognises antigen-MHC complex via the T cell antigen receptor (TCR): provides “Signal 1” to T cell
- CD80/CD86 on B cell binding to CD28 on T cell provides “Signal 2” to T cell
- T cell activation leads to up-regulation of CD40L which bind to CD40 providing “Signal 2” to B cell
- Cytokine production by activated T cell also help to activate B cell…“Signal 3”
- B cell proliferates and differentiates into antibody secreting B cell (plasma cell) or becomes a memory B cell
- Sequence of events:
80
Q
T-dependent B cell response
- T-dependent B cell responses requires a three-signal process:
- Sequence of events:
- Antigen binding to BCR provides “Signal 1” to B cell
- Antigen is internalised, processed and antigenic peptides are displayed on MHC for T cell recognition
- TH (helper T-cell) recognises antigen-MHC complex via the T cell antigen receptor (TCR): provides “Signal 1” to T cell
- CD80/CD86 on B cell binding to CD28 on T cell provides “Signal 2” to T cell
- T cell activation leads to up-regulation of CD…L which bind to CD… providing “Signal 2” to B cell
- Cytokine production by activated T cell also help to activate B cell…“Signal 3”
- B cell … and differentiates into antibody secreting B cell (plasma cell) or becomes a memory B cell
- Sequence of events:
A
- T-dependent B cell responses requires a three-signal process:
- Sequence of events:
- Antigen binding to BCR provides “Signal 1” to B cell
- Antigen is internalised, processed and antigenic peptides are displayed on MHC for T cell recognition
- TH (helper T-cell) recognises antigen-MHC complex via the T cell antigen receptor (TCR): provides “Signal 1” to T cell
- CD80/CD86 on B cell binding to CD28 on T cell provides “Signal 2” to T cell
- T cell activation leads to up-regulation of CD40L which bind to CD40 providing “Signal 2” to B cell
- Cytokine production by activated T cell also help to activate B cell…“Signal 3”
- B cell proliferates and differentiates into antibody secreting B cell (plasma cell) or becomes a memory B cell
- Sequence of events:
81
Q
T-dependent B cell response
- T-dependent B cell responses requires a three-signal process:
- Sequence of events:
- Antigen binding to BCR provides “Signal 1” to B cell
- Antigen is internalised, processed and antigenic peptides are displayed on MHC for T cell recognition
- TH (helper T-cell) recognises antigen-MHC complex via the T cell antigen receptor (TCR): provides “Signal 1” to T cell
- CD80/CD86 on B cell binding to CD… on T cell provides “Signal 2” to T cell
- T cell activation leads to up-regulation of CD40L which bind to CD40 providing “Signal 2” to B cell
- Cytokine production by activated T cell also help to activate B cell…“Signal 3”
- B cell proliferates and … into antibody secreting B cell (plasma cell) or becomes a … B cell
- Sequence of events:
A
- T-dependent B cell responses requires a three-signal process:
- Sequence of events:
- Antigen binding to BCR provides “Signal 1” to B cell
- Antigen is internalised, processed and antigenic peptides are displayed on MHC for T cell recognition
- TH (helper T-cell) recognises antigen-MHC complex via the T cell antigen receptor (TCR): provides “Signal 1” to T cell
- CD80/CD86 on B cell binding to CD28 on T cell provides “Signal 2” to T cell
- T cell activation leads to up-regulation of CD40L which bind to CD40 providing “Signal 2” to B cell
- Cytokine production by activated T cell also help to activate B cell…“Signal 3”
- B cell proliferates and differentiates into antibody secreting B cell (plasma cell) or becomes a memory B cell
- Sequence of events:
94
Q
The development of immunological memory in a population leads to the concept of … … and this slows or even prevents the spread of infectious agents. However, for … … to be effective >60% of the population needs to have been infected and recovered from the pathogen.
A
The development of immunological memory in a population leads to the concept of herd immunity and this slows or even prevents the spread of infectious agents. However, for herd immunity to be effective >60% of the population needs to have been infected and recovered from the pathogen.
