Lecture 2 Flashcards
What do all blood cells arrise from?
HSCs - hematopoietic stem cells
What is hematopoiesis?
Process by which HSCs become other types of blood cells
What is required for HSC self renewal?
HSCs must be surrounded by a niche for renewal
Where are HSCs found?
In niches of osteoblasts or senusoidal endothelial cells in the bone marrow
What do niches supply?
Supply HSCs with GF and other regulatory molecules
Where else can HSCs be found?
Ciruculating but chemical signals encourage them to home back to marrow to niches
How is HSC return to circulation controlled?
Circadian manner
What can push HSC to differentiate?
Stromal cell factors
What do stromal cells do?
Push HSCs to differntiate into peripheral celsl
Two paths HSC can take?
- Commy myeloid
2. Lymphoid progenitor
What can common myeloids become?
- RBCS
- Thrombocytes
- Any of the leukocyte cells
What signals lead to basophil development?
IL4
What does IL4 lead to?
Basophils
What leads to Neutrophil development?
G-CSF
What does G-CSF lead to?
Neutropihls
What leads to EOSs?
IL5
What does IL5 lead to?
EOSs
What leads to monocyets/macros?
GM-CSF
M-CSF
What does GM-CSF & M-CSF lead to?
Macrophages
Monocytes
What leads to DCs?
FLT3l
What does FLT3l lead to?
DCs
What leads to T cells?
IL2
IL7
What do IL 2 & 7 lead to?
T cells
What leads to B cells?
IL3 & IL7
What do IL3 & IL7 lead to?
B cells
What are lymphocytes responsible for?
Setting up specific responses to pathogens
Where to lymphoctyes travel?
Between lymphoid organs hoping to find matching antigen
What do lymphocytes do if find their match in lymph?
Become activated and go to site of infection
What are some lymphoid deptots?
- Lymph nodes
- Mucosal lymphoid tissue, eg intestine
- Spleen
- Tonsils
What happens in lympoid organs?
Immuce cells are displaying pathogens they have found to lymphocytes hoping to find match and commence immune response and activate lymphocyte
Path of lymphocyte?
- Lymph drainage into thoracic duct then to left subclavian vein
- Will follow chemical signals to site of infection
How can neutrophils be recognized?
- Multilobed nucleus
- Light pink on staining
Characterisitcs of neutrophils?
- Granulocytic myeloid cells
What is the most abundant WBC?
Neutrophil
What is neutropenic?
Low in Neutrophils, will succumb easily to othewise non lethal infections without intervention
What is the foot soldier of the immune repsonse?
Neutrophil
How long to neutrophils last?
1 round of phagocytosis
Where are neutrophils usually found?
- Circulation
- Move to site of infection when signalled
How do neutrophils kill?
Phagocytosis unless the pathogen is too large then they can engage in extracellular killing
How doe neutrophils engage in extracellular killing?
Spill contents of antimicrobial granules into extracellular space
What is bad about extracellular killing?
Granule content also harms tissues
What are NETs?
Neutrophil extracellular traps that are full of granular enzymes and killing molecules and DNA elemments that can imobilize pathogens
Clinical manifestation of neutrophil activiation?
Pus
What is majority of pus content?
Neutrophils
Do macs have granules?
No, are filled with lysosomes become primary process is phagocytotic
Main processes of macs?
- Phagocytosis
2. APC to T cells
Precursor of macs?
Monocytes, named so as they are mononuclear (not lobed)
Are macs abundant?
Not orignally, when find pathogen then signal to Ts and nuetrophils for help and T cells which enhance their phagocytotic activity
What other rolls do Macs play?
General house keeping of dead cells when no infection
Are mac receptors specific?
NO
Was is bacteremia?
Bacterial infection of the blood which can lead to sepsis and quick death
Primary focus of DC?
Antigen presentation to adaptive immune system
Where are DCs found?
In nealry all tissues sampling and searching for pathogen
What would happen in no DCs?
The T cell response would probably not ever be activated
What cell is best at antigen presentation?
DC
In what ways can DCs display antigen?
- Phagocytosis
- Micropinocytosis
- Share molecules from own infection
How are EOSs recognized?
- Bright pink staining
- Bi lobed nucleus
Main job of EOS?
Destroying large parasites
What is responsible for destroying large parasites?
EOS
Where are EOSs found?
Subepithelial connective tissue
What do EOS enzymes do?
Descruct tissues and pathogens
Recruit more inflamation
Promote vascular permeatbility
Clinical role of EOS?
Can augment and help to sustain allergic reaction possibly causing permanent damage to tissue
What do mast cells contain?
Histamine
What has the specialty of histamine relief?
Mast cells
Main job of mast cells?
Open vascular doors for WBC to move to infection
What can happen if mast cell goes awry?
Systemic vasodilation leading to loss of BP, airway constriction, swelling of epiglotis and death
What is urticaria?
Hives caused by mast cells when absorbed/ingested allergens reach skin
What do basophils do?
Participate in allergen and parasitic reaction with mast cells and EOSs
What do NK cells like to attack?
Viruses and tumors
What does invariant mean?
Not specific
What type of receptors do NK cells have?
Invariant
What can NK cells detect?
Virus in cell or its movement to becoming tumorogenic
How do NK cells kill?
Release of ctyotoxic granules inducing target to apoptose
What do activated B cells do?
Become plasma cells making antibody
Describe B cell receptors?
Antigen specific
Are the same as antibobies but just bound to cell
What do ciculating antibodies do?
Trap pathogen allowing it to be more easily eaten
What are commanders in chief of immune system?
T cell
Two types of T cells?
Helper & Cytotoxic
What type of receptors do T cells have?
Specific
What happens when T cells encounter antigen?
Proliferate and differentiate
What do Killer T cells do?
Recognize and kill viral cells
What do helper T cells do?
When activated produce molecules and ctyokines that direct immune response by macrophages and B cells and augment recruitment to site of infection
