Lecture 20- Adaptive Immunity 2 Flashcards
What do ATC’s do when activated with antigen?
Travel to lymph node
Where in lymph node are b and T cells
B cells in lymphoid follicle
T cells in parafollicular cortex
Whatcauses autoimmune disease?
When cells act against self antigen
Where are b and T cells produced and where do they mature?
Produced in bone marrow
T cells mature in thymus and B cells in tissues
Why do lymph nodes swell during infection?
Lymphadenopathy- B cells and T cells become activated
What happens with activation of CD4+ T cells also known as T helper cells?
They go on to help B cells produce antibodies
Clinically important lymph nodes?
Cervical
Axillary
Inguinal
Antibody response?
Bacteria
Effector T cell cytotoxic response?
If virus
Antigen recognition by T lymphocytes?
Antigen recognition receptor (t cell receptor TCR)
Great diversity to recognise different antigens
CD4+ helper T cells recognise MHC class 2 while CD8+ recognise MHC class 1
How are T cells activated on recognition of an antigen?
3 signals
Antigens presented by MHC 1 or 2
Cytokines released
Effect of cytokines on activation of CD4+ cells?
Cytokines released depends on type of microbe and cause different sub types of CD4+ cell to arise
can get TH1 cells responsible for cell mediated immunity (intracellular and extracellular pathogens)
TH1 help B cells produce antibodies
Th2 cells responsible for humoral immunity (extracellular pathogens)
TH17 causes neutrophil recruitment and activation
Treg causes immune suppression
What happens if there is a virus in an APC?
APC,s have class 1 and 2 MHC molecules so will activate CD4+ and CD8+ cells
Effector functions of CD8+ cells?
Require TH1 cells to become activated and have cytotoxic function
Naive CD8+ cells can either become cytotoxic in activation as above or memory CD8 cells
Cytotoxic will kill all MHC class 1 cells
B cell antigen recognition?
Do not need antigens to be processed
Endocytosis and present through MHC class 2 to helper T cells
Get antibody and cytokine production
Outcome of B lymphocyte activation?
IgM production which is T helper independent
IgG, IgE and IgA which is T helper dependent. This is why IgM is seen first.
Disease can be detected at lower concentration in future
Memory B cells for long lasting immunity
What can antigen stimulated B cells become?
Plasma cells which produce IgM and are T cell or thymus independent
Other cell types which are thymus dependent and produce the other antibodies
Memory B cells
Relevance of IgM and IgG clinically?
If high IgM and no IgG then first time exposure to antigen.
If IgG present then secondary exposure and immunity should be there
Effector functions of antibodies?
IgG- complement activation, can give vertical immunity for 6 months to offspring (autoimmune risk)
IgE- good against parasites
IgA- mucosal immunity
IgM-complement activation
