What are granulocytes characterized by and how long is there lifespan
- irregular multilobed nuclei
- characterized by preformed cytosolic gansules (inside secretory vesicles)
- Short lifespans of 1-5 days
Neutrophils- how common, when do they respond to injury and how do they move
- most abundent leukocyte (60%)
- first blood cell to extravasate to injured/infected area
-When activated can move via ameboid movement
How do neutrophils function
Phagocytosis of microbes/dead cells/tissue debris
- Phagocytized content enters endosomes which have low pH
- join lysosome (which have even lower ph, and lypsosomal hydrolytic enzymes)
- also has respiratory burst (rapid release of ROS)
What occurs in respiratory burst
NADPH(NOX2) is activated and catalyzes breakdown of O2 to superoxide
Supraoxide + myeloperoxide converts o2 to hydrogen peroxide which can further breakdown to ROS
ROS/HOCL/RNS can all erode endosomal content + lead to death
Types of neutrophil granules ( in order of dev + function)
(all 4 will be there in the end)
- Azurophilic- ROS and killing within phagosomes
- Specific- Intra/extracellular killing
- Gelatinase- migration + extravasation
- Secretory- Adherence
What are neutrophil NETs (+ activation sigs for them)
- Activated neurtrophils secrete extracellular webs made of antimicrobial pros and chromatin.
- Kill microbes extracellulary and help contain infections
Activiated by: microbes, cytokines
What % of WBC does eosinophils compromise, what do they attack and how
1-4% of all WBCs
Tend to attack paricites that are too big to pagocytos by sereting granules containing cationic peptides
when not attacking pathogens what do eosinophils typically do
Produce inflammatory mediators that contribute to allergy and asthma (leukotrienes)
What % of WBC does basophils compromise and what do they do/release
Contribute 0.5-1% of WBCs
- produce heparin which is an anticoagulant
- produce inflammatory mediators: cytokines/histamine/serotonin/leukotriens
Where are MAST cells found and what do they release when they are activated
resident cell of connective tissues of the skin and mucus membranes (contain preformed granules that are released when mast cells are activated causing degranulation)
-can be triggered by allergens, cytokines, physical injury, infection etc
What % of WBCs are monocytes, what do they do and what can they differentiate into
2-10%
- Phagocytosis of extracellular foreign material
- maintainance of inflamation
-can differentiate into macrophages/dendritic cells
what do macrophages do and what are the 2 types
Phagocytosis of microbes, dead cells, tissue debris
-type of antigen presenting cell
M1- proinflamatory/antimicrobial
M2- Repair and regeneration
What are dendritic cells and the main function of them
Professional antign presenting cells (important for t cell activation and differentiation)
-called conventional dendritic cells
what are the 3 professional antigen presenting cells
Cdendritic cells
Macrophages
B cells
What are plasmacytoid dendritic cells
- type of innate cell (not professional APC)
- pDC produce type 1 IFN in response to infection w viruses (interferes w viral replication)
What % of circulating WBC is lymphocytes
25% of circulating WBCs
What markers do cDC have compared to pDC
cDC- CD11c markers
pDC- BDCA2 markers
what are the 4 innate lymphocytes
- Innate lymphoid cells (NK cells ILC1/2/3, lympod tissue inducer)
- NKT cells
- B-1 cells
- Gamma delta T cells
Function of innate lymphoid cells and where are they found
Primary tissue resident cells found in lympoid and non lymphoid tissues (but NOT blood)
-secrete effector molecules such as cytokines
Function of NK cells (+how do they kill)
cytotoxic cells that patrol body for infection and cancer
- kill tageted cells by ecreteing pro apoptotoc factors such as perforin and granzymes
- also secrete proinflammatory mediators (interferon gamma, TNFa)
How are NK activated
NK killer activity is mediated by sum of signals on cell surface (either activating or inhibitory receptors)
How do NK know when to kill
MHC1 acts as inhibitory receptor ligand and when interaction takes place NK cell turns off and targeted cell isn’t killed (prevents from killing healthy cells, cuz its on every cell!)
Certain microbes and cancers cause cells to loose expression of MHC1, so NKs can be active on them.
Function of NKT, Gamma delta t cells and b1 cells
NKT- produce large quantities of cytokines
Gamma delta- produce large quntity of cytokines
B1- produce antibodues w no memory
What are CD8 and CD4 t cells
CD8- killer t cells
CD4- Helper t cells
