White Blood Cells and Immune responses Flashcards
1
Q
What are the components of the immune system?
A
2
Q
What WBCs are known as auxiliary cells?
A
- Basophil
- Mast cells
- Platelets
They act as inflammatory mediators
3
Q
What WBC type are granulocytes?
A
- Neutrophils
- Eosinophils
- Basophils
4
Q
What are Mast cells?
A
- not found in blood only in the tissue
- releases substances that affect vascular permeability
- prominent in mucosal and epithelial tissue
- Express FceRI (binds IgE)
- release granules containing histamine and other active agents
5
Q
What is the breakdown of Blood counts in adults?
A
- neutrophils 50-70% - lymphocytes 20-40% - monocytes 3-10% - Eosinophil 1-3% Basophil <1%
6
Q
What is the role of NK cells?
A
- act as part of the adaptive immune system
- 5% of lymphocytes
- non-specific antigens
7
Q
What are Basophils and what do they do?
A
- cells that are lobed nuclei and heavily granulated cytoplasm
- express FceRI
- circulate in the blood
- recruited to sites of allergic reaction or ectoparasites
- Non-phagocytic cell
- can bind to allergen-specific IgE
8
Q
What are Eosinophils and what do they do?
A
- bilobed nuclei with a granulated cytoplasm: granules contain peroxidases (toxin)
- motile phagocytic cells: migrate from the blood into tissues
- play a role in defence against the parasitic organism: in the GI respiratory and genito-urinary tracts
- Express FceRI when activated
9
Q
Describe the physiology and biology of Neutrophils
A
- polymorphonuclear cells
- multilobed nucleus
- found in the blood: makeup 60% of circulating leukocytes
- short lifespan: 8hr- 4days
- release myeloperoxidase and ROS
10
Q
What is ROS and what does it do?
A
Reactant Oxygen Species
- oxygen-containing molecules that have an extra, highly reactive electron ( O2-)
- oxygen radicals donate their electrons to other nearby molecules at random and can damage macromolecules in a random way
- not a specific mechanism and can damage nearby molecules of the host
11
Q
Describe the physiology and biology of Monocytes
A
- kidney-shaped nucleus
- there is a reservoir of monocytes in the spleen
- circulate the bloodstream where they are enlarge
- migrate into tissue approx. 1 day after release from the bone marrow
12
Q
Describe the physiology and biology of Macrophages
A
- they are tissue-specific:
- 5-10x larger than monocytes: contain more organelles as well e.g lysosomes
- lifespan is months to years
13
Q
What is the primary response of leukocytes in bacterial infection?
A
- increase in neutrophils
- increase in monocytes in a chronic infection
14
Q
What is the primary response of leukocytes in viral infection?
A
- increase in lymphocytes; sometimes an increase in monocytes
15
Q
What is the primary response of leukocytes in parasite infection?
A
- increase in eosinophils + activation of mast cells
16
Q
What is the primary response of leukocytes in a fungal infection?
A
- increase in monocytes
17
Q
What is the primary response of leukocytes in allergy?
A
- increase in basophils
- activation of mast cells
- increase of eosinophils in the chronic phase
18
Q
What are the three areas of pathogenesis in Atherosclerosis?
A
- Dysregulation of lipid metabolism (cholesterol)
- Endothelial cell dysfunction
- Inflammation: mediated by monocytes and macrophages
19
Q
What are key indicators of Acute inflammation?
A
- develops within minutes
- predominantly mediated by neutrophils
- resolves once the stimulus is removed
- lasts for hours or days
20
Q
What are key indicators of Chronic inflammation
A
- predominantly mediated by mononuclear cells; macrophages,lymphocytes
- tissue destruction
- attempts at healing (fibrosis)
21
Q
What is MCP-1?
A
- Monocyte chemotactic protein-1
- aka CCL-2
- this is a chemokine, whose function is to attract leukocytes; in this case monocytes would be attracted
22
Q
What are the two types of contact between the endothelium and circulating cells?
A
Initial Contact
- P-selectin and E-selectin on endothelium recognized by oligosaccharides on leukocytes
Tighter adhesion
- intercellular adhesion molecules (ICAMs) on the endothelium recognised by integrins on leukocytes
23
Q
What are the Adhesion molecules on the surface of the endothelium for Transient Initial Contact?
A
- P- selectin binds to PSGL-1, sialyl-Lewisx
- E-selectin binds to sialyl-Lewisx
24
Q
Explain the platelet monocyte interaction
A
- platelets bound to the endothelium express P-selectin and other endothelial ligands
- monocytes with complementary proteins, PSGL- 1 and MAC-1 bind to the platelet
- this activates the monocyte –> inflammation of the monocyte
25
Explain the activation of macrophages by pathogens.
What do the macrophages release when they are activated?
- activated macrophages also release proinflammatory cytokines:
- IL-1ß, TNF-alpha, IL-6
26
How do phagocytes recognise what to ingest?
Through pattern-recognition receptors such as:
- Macrophage mannose receptor
- Scavenger receptors
- Toll-like receptors (TLRs)
27
What is/are the corresponding ligand(s) to scavenger receptors?
- anionic polymers
- acetylated and oxidised LDL
28
What is/are the corresponding ligand(s) to macrophage mannose receptors?
- conserved carbohydrate structures
29
What is/are the corresponding ligand(s) to Toll-like receptors (TLRs)? (trick)
- there is a range of them
30
What WBCs are known as phagocytes?
- Mononuclear
- Neutrophil
- Eosinophil
31
What WBCs are known as lymphocytes?
- B cells
- T cells
- Large granular lymphocytes
32
What are cytokines?
- these are proteins or glycoproteins with a low molecular weight
- that act as messenger molecules in the immune system
- primarily secreted by WBCs
- assist in regulating the development of immune effector cells
- they generally act locally: paracrine signalling
33
Explain the process of recruitment of monocytes at the site of inflammation
34
What are the Adhesion molecules on the surface of the endothelium for Tighter binding
**- ICAM-1 (CD54):** binds to LFA-1, Mac1
**- ICAM-2 (CD102):** binds toMac1
- **VCAM-1 (CD106):** binds to VLA-4
LFA-1 – Lymphocyte function-associated antigen 1
VLA-4 – Very Late Antigen-4 (Integrin alpha4beta1)
VCAM-1 – Vascular cell adhesion molecule
35
What does VCAM-1 – Vascular cell adhesion molecule do and where is it expressed?
- it binds monocytes and lymphocytes to _activated_ cell endothelium
- expressed by endothelium over nascent fatty streaks
- expressed by microvessels of the mature atheroma
