Immune System Flashcards
What physical barriers are there?
- skin
- nose hairs
- flow of urine
What chemical barriers are there?
- urine pH
- gastric enzymes
How would you describe the innate immune system?
- the first line of defence
- non-specific
What do complement proteins do?
- promote inflammation
- recruit and activate inflammatory cells
- kill target cells
What do Ca proteins do?
They are sent on a mission
What do Cb proteins do?
Stay on site
How can C3 be activated?
- mannose binding lectin
- classical pathway
- alternative pathway
What does C3a do?
Mast cell activation
What does C3b do?
Opsonisation
What does C5a do?
Mast cell activation and chemotaxis
What does C9 do?
Cell lysis (MAC)
What do the PRRs detect?
PAMPs or DAMPs
What does PRR stand for?
Pattern recognition receptors
What does PAMP stand for?
Pathogen Associated Molecular Patterns
What effect do the PRRs have?
- Endocytolic - phagocytosis
- signalling (e.g. TLR) - pro-inflammatory mediators
How would you describe the acquired immune system?
Specific
What two types of cell signalling are present in acquired immunity?
- cytokines
- antigen presenting cells
What kind of cytokines are present?
- interleukins (between leukocytes)
- chemokines
What are antigens presented by?
MHC I
MHC II
What cell does an activated B cell become?
Plasma cell
What is IgM?
It is the first antibody
Where is IgG found?
Blood antibody
Where is IgA found?
Mucosa antibody
What is IgE?
Parasite and allergy antibody
What is IgD?
BCR (B cell receptor)
What steps are involved in neutrophil migration?
- Margination
- Adhesion
- Diapedesis
What happens when the virus infects the cell?
It starts replicating and this activates the PRRs (e.g, TLR)
What does activation of the PRR do?
- upregulation of IL-8
- expression of pathogenic peptide on MHC i
What do IL-8 and inflammatory mediators do?
Attract dendritic cells and macrophages to the site of infection, where they phagocytose cell debris and viral particles
What do the dendritic cells do after phagocytosis?
- They are activated
- express viral particles on MHC I and MHC II
- Activated APC migrate to the lymph node
- DCs activate Th1 (and Th2 to an extent) through signals
How does a DC activate Th1?
- antigen presentation via MHC II with TCR (I want you to activate)
- stimulation of naïve T cell CD28- co-stimulatory signal (yes I really do want you to activate)
- release of IL-12 - differentiation to Th1
How are CD8 cytotoxic T cells activated?
- interacts with the DC via MHC I
- Th1 licenses CD8+ ct via IFN-gamma and IL-2
What happens to the activated CD8+ ct?
- Memory T cells stay in the lymph node for the next time the pathogen infects the body (faster response)
- Effector T cells migrate to the site of infection and look for cells expressing the same peptides on MHC I
How do the CD8+ ct trigger apoptosis of infected cells?
They release perforin and granzyme
What does perforin do?
Creates holes in the target cell’s membrane (perforates the membrane)
What does granzyme do?
Triggers a series of reactions leading to the target cell’s DNA being chopped up
What happens when bacteria infect us?
- complement pathway activated
- inflammation
- neutrophils and dendritic cells are attracted to the site of infection and carry out phagocytosis
