5 - Cells of the Innate Immune System - Angyal Flashcards
Draw a diagram highlighting all the cells of the innate immune system.
311 - 5 word Q1.
Name the 3 professional phagocytes
Neutrophils, monocytes, macrophages
Describe the process of phagocytosis
1) phagocyte binds to the bacteria, helps if Abs bound to pathogen (opsonisation)
2) pseudopods extend around the pathogen
3) invagination of phagocyte membrane leading to phagosome formation
4) fusion of lysosome w/ phagosome -> phagolysosome. here enzymes eg lysozyme break down macromolecules. ROS/RNS are also produced
5) release of microbial products
6) if it is an APC then the peptides are presented on the surface of the cell on the MHC-II molecules to present to other T cells
Name the 3 types of polymorphonuclear granulocytes and list them according to their abundance (most abundant being first)
neutrophils, eosinophils, basophils
Describe eosinophils and basophils in terms of their…
i) % in blood & any other locations
ii) their granules and contents
iii) their activity and organisms they’re effective against
iv) any receptors?
v) what they release
vi) any similarities?
EOSINOPHILS;
i) 6%, also found in connective tissue under mucous surfaces
ii) granules contains enzymes harmful to opsonised parasites
iii) phagocytic activity. also can cause damage to host tissue. effective against multicellular organisms eg parasites
iv) receptors for C3b, IgG, IgE
v) release histamine, cytokines (IL4), prostaglandin
BASOPHILS;
i) <1% in blood
ii) preformed granules similar to mast cells
iii) Effective against parasites
iv) Fc receptors, C3a,C5a, IgE
v) release histamine, cytokines (IL4/13)
vi) both effective at targeting pathogens and both play role in allergy, bth have IgE receptors and release histamine
what is the % composition of neutrophils in the blood?
50-60%
Under what conditions are neutrophils activated and where can they be released from if needed in high numbers?
upon infection -> hypoxic conditions -> activation and release into tissue. vast quantities can be released from the bone marrow if necessary.
What is the lifespan of a neutrophil?
6h - 1/2 days. if reaches the tissue they can persist for much longer when dealing with infection
What are the 2 types of granules present in a neutrophil?
specific - lysozyme, elastase, collagenase
auzrophillic - microbicidal substances eg defensins
What happens to the neutrophil once the bacteria has been pahogcytosed/infection has been dealt with?
death by apoptosis
What are the functions of neutrophils?
- phagocytosis
- release of granular contents eg lysozyme, defensins
- netosis. once neutrophil is dying can release neutrophil extracellular traps (NETs). DNA, proteins expelled which traps microbes
- cytokine production
- production of ROS/RNS
What is the process of neutrophil movement into tissues called?
diapedesis - extravasation of neutrophils into surrounding tissue
Describe the structure of mast cells
ovoid nucleus with cells that look elongated
Where are mast cells predominantly located?
mature cells are tissue-resident that protect mucosal surfaces
What do mast cells preformed granules contain?
ser proteases, histamine (therefore allergy response)