Innate Immunity Flashcards
3 Polymorphonuclear cells of the innate immune system
Neutrophils, Eosinophils, Basophils
What do dendritic cells do?
Link between innate and adaptive
2 types of dendritic cells:
Dendritic Cell and Follicular Dendritic Cell
Difference between dendritic cells and follicular dendritic cells: 5
Dendritic cells are widespread, have MHC II, CD 80 and 86, are phagocytic and show processed Ag to T cells
FDC: In germinal centers of secondary lymphoid, no MHCII, no CD80 and CD86, no phagocytosis, show naive antigen to b cells
What are dendritic cells in skin called?
Langerhan’s cells
What do CD80 and CD86 interact with? what happens if none?
CD28 on T cells - if absent, T cells programs death
What do eosinophils act against? how?
Large parasites - release granule contents for extracellular killing
What is in eosinophil granule content?4
Major basic proteins, cationic protein, oxygen metabolites, perforin
What is the main role of basophils and mast cells?
Getting rid of parasitic worms
How do basophils and mast cells work?
Coat themselves with IgE by FcE receptor. Antigen cross links 2 FcER — inflammatory mediators released
5 Inflammatory mediators from basophils and mast cells (Stored and new):
Stored: Histamine and serotonin
New: TNF alpha, prostaglandin, leukotrienes
5 molecules of innate immunity:
PRRs, complement, APP, Defensins, Cytokines
3 things acute phase response does:
1- Enhances host resistance to infections and minimises tissue injury
2- Promotes resolution and repair of inflammatory lesions
3- Cytokines release due to PRR activation, act on liver to increase secretion of APP
3 cytokines that act on the liver in APP
IL1 , IL6, TNF
3 things produced by liver during APP:
1- C3 complement component
2- C-reactive protein which activates complement
3- Fibrinogen coagulation
What are defensins? 4
- Nature’s antibiotic
- Small cationic antimicrobial peptides
- Widely expressed, esp by leukocytes and epithelium
- Intracellular and secreted
Two types of defensins - difference:
alpha defensins - constitutively expressed
beta defensins - some constitutively expressed, others induced
How does immune system recognise antigens?
Use intracellular, cell surface and secreted PRRs
What does the PRR recognise?
PAMPS and DAMPs
Protein diversity of PRRs in individual:
10s - 100s
Genes of PRR:
Each protein individually encoded, low polymorphism
What are TLRs?
A large group of PRRs.
3 TLRs on cell surface + what recognise:
TLR2- lipoproteins (gram +ve proteoglycan)
TLR4 - LPS (gram -ve)
TLR5- flagellum
4 TLRs endosomal compartment + recog:
TLR3 - viral dsRNA
TLR 7 and 8 - ssRNA nucleotide analogue
TLR9 - unmethylated CPG DNA
What do TLRs do?
Activate NFkB and IRF
What does mannose receptor detect?
Terminal mannose
What is the complement system?
Large number of molecules, many are pro - go on and activate another enzyme in a cascade like fashion
Opsonisation
Coating a microorganism to make it more readily recognisable by the phagocytic cell
What are the two main types of molecules that opsonise microorganisms?
Antibodies and complement proteins
How does opsonisation work?
Phagocytic cells have molecules on their cell surface that recognises the ab or complement (CR)
What are complement components also involved in?
chemotaxis and increasing vascular permeability as they make mast cells and basophils release inflammatory mediators
What are cytokines?
Small secreted proteins that act as messengers between cells
5 main groups of cytokines are:
IL, Colony stim factors, chemokines, IFN, TNF
Functions of cytokines include 2:
control of Haematopoiesis and immune responses
