Immunology Flashcards
What is the role of the immune system?
- identify and eliminate microrganisms, harmful substances and abnormal cancer cells
How can we manipulate the immune system?
- immunization
- anti-inflmmatory/immunosupression drugs
- cancer immunotherapy
What is innate immunity
- present continously
- from birth
- non-specific
- quick response
What is acqruired immunity?
- induced by prescence of foregin objects
- specific
- slower response
What is the most important barrier to infection?
- the skin
meaning of commensal?
- part of the normal floar
explain phagocytosis?
- macrophages express PRR
- bind to PAMPs on pathogen
- form phagosome
- fusion with lysommones
- debris released
- MHC-11 display pathogen particles
How can phagocytosis be enhanced?
- opsonisation
- cover the pathogen in soluble factors(opsins)
Examples of opsonins?
- C3b
- IgG/IgM
- CRP
What can a mast cell do?
- degranulation
- gene expression
What are examples of pro-inflammatory substances?
- nitric oxide
- prostaglandis
- histamines
- pro-inflammatory cytokines
Name 4 cells involved in innate immunity?
- macrophages
- mast cells
- neutrophils
- natural killer cells
What can the complement system cause a cascade of?
- opsonization of pathogens
- direct pathogen killing
- acute inflammation
- leukocyte recruitment
Explain the complement system
C3 --> C3b + C3a (by MBL) C3b binds to pathogen acts as a C5 convertase C5 --> C5b + Cba C5b binds to pathogen --> MAC (membrane attack complex)
What acts as acute inflammation triggers in the complement cascade?
- C3a
- C5a
Explain the process of neutrophil recruitment and initation
- proinflammatory mediators cause vasodilation and an increase in vascular permebility of the endothelial cells of blood vessels
- neutrophils margination and rolling
- binding to adhesion molecules (ICAM-1)
- transendothelial migration (diapedesis)
- chemotaxis
- phagocytosis, degranulation, NETs
How are virally infected cells destroyed?
- release small proteins called interferons
- warn nearby cells of the presence of a virus
- induce apoptosis by natural killer cells
What do natural killer cells do?
- kill virally infected cells and abnormal cancer cells
- by causing apoptosis
Where do B cells mature?
- the bone marrow
Where do T cells mature?
- the thymus
What are B cells responsible for?
- producing antibodies that attack pathogens
- humoral immune response
What are T cells responsible for?
- cellular immune responses
- CD4+ T cells (helper)
- CD8+ T cells (killer)
Explain the structure of an antibody
- 4 polypeptide chains
- 2 x light chains
- 2 x heavy chains
Where are the 2 primary lymphoid tissues?
- bone marrow
- spleen
What are plasma cells?
- produce and secrete soluble antigen specific antibodies
What are memory B cells?
- long lived cells that continue to circulate around the body
What 2 signals does a B cell recieve before it is activated?
- BCR binding
- Th cell or PRR + PAMP
IgM? structure
- first Ig produced
- pentamer structure
Functions of IgM
- aggultination
- complement system activation
What is agglutination?
- clumping together to form an immune complex
- IgG and IgM
- enhances phagocytosis
What is the structure of IgG?
- Monomeric
What is the function of IgG
- 2nd to be produced
- most abundent Ig
- can be passed across the placenta
- agglutation
- opsonisation
- activating NK cells
IgD?
- Low levels
- surface bound
IgA?
- 2nd most abundent
- monomeric in blood
- dimeric in breast milk
What 2 Ig can be passed from mother to infant?
- IgG (across placenta)
- IgA (breast milk)
IgE?
- Triggers allergic responses
Explain the role of CD4+ T cells?
- key regulators of the entire immune system
Explain the role of CD8+ T cells?
- kill virally infected body cells
Explain the make up of a TCR?
- T cell antigen receptor
- membrane bound protein heterodimer
- composed of an alpha and beta chain
T cells can only recognise _____ antigens present to their TCR by _________
- T cells can only recognise peptide antigens present to their TCR by MHC molecules
What does MHC stand for and what are their roles?
- Major histocompatibility complex
- displays peptide antigens to T cells
What are class I MHC molecules?
- expressed on all nucleated cells
- present peptide antigens to CD8+ T cells
What are class II MHC molecules?
- only expressed on professional antigen presenting cells
- present peptide antigens to CD4+ T cells
Examples of proffessional antigen presenting cells?
- dendritic cells
- macrophages
- B cells
CD4+ T cells release what growth factor?
- IL 2
- Stimulates further proliferation of CD4+ T Th0 cells and increases CD8+ T cell proliferation
What do CD8+ T cell proliferate into?
- Cytotoxic T lymphocytes
- kill virally infected cells
Function of TFH cells?
- germinal centre reaction
- B cell co-stimulation
Function of TH1 cells?
- increases macrophage killing
- releases pro-inflammatory cytokines
