Week 102: Swollen Finger Flashcards
1
Q
Why are abscesses hard to treat?
A
- No blood supply
- Antibiotics need actively dividing cells to work
- Chemical nature of pus can interfere with antibiotics
⇒ Antibiotics can’t get there, work and can be damaged!
2
Q
Autocrine cytokines
A
Work on themselves
3
Q
Parakryne cytokines
A
Work on surrounding cells
4
Q
Endocrine cytokines
A
Enter the blood stream - e.g. insulin
5
Q
What are toll-like receptors?
A
- A class of proteins that play a key role in the innate immune system and digestive system
- Single, membrane-spanning, non-catalytic receptors
- Found in sentinel cells such as macrophages and dendritic cells
- Recognise structurally conserved molecules derived from microbes
- Once these microbes have breached physical barriers such as the skin or intestinal tract mucosa, they are recognized by TLRs, which activate immune cell responses
6
Q
What are interleukin receptors?
A
Cytokine receptors for interleukins
7
Q
What are interleukins?
A
- A group of cytokines (secreted proteins and signalling molecules) that are expressed by leukocytes (white blood cells)
- Mainly synthesised by helper T cells
- Help development and differentiation of T lymphocytes, B lymphocytes and hematopoietic cells
8
Q
What are NOD-like receptors?
A
- Large family of cytoplasmic proteins that contain leucine-rich repeats which bind to bacterial components
- NOD1 and NOD2 recognise fragments of bacterial cell wall proteoglycans, and are found at particularly high amounts in the epithelial cells that line the gut
9
Q
What is transferrin?
A
- Takes up iron from environment and blood stream
- Microorganisms need iron so deprives
10
Q
What are interferons?
A
- A family of proteins produced rapidly by many cells in response to viral infections, which block the replication of virus in the infected cell and neighbour
- Have a role in communication between immune cells
11
Q
Fibronectin
A
- Same as a complement protein, opsonisation (attaches and labels for immune system)
12
Q
What are defensins?
A
- Antimicrobial peptides, particularly important in the early protection of the lungs and digestive tract against bacteria
⇒ Innate immune system
13
Q
What are lysozymes?
A
- An enzyme secreted by macrophages that attacks the cell wall of some bacteria
⇒ Innate immune system
14
Q
What is the complement?
A
- A group of proteins present in serum which when activated produce widespread inflammatory effects, as well as lysis of bacteria etc.
- Some bacteria activate complement directly, while others only do so with the help of antibodies
⇒ Innate immune system
15
Q
What is lysis?
A
- Irreversible leakage of cell contents following membrane damage
- In the case of a bacterium this would be fatal to the microbe
⇒ Innate immune system
16
Q
What is a mast cell?
A
- Large tissue cell that releases inflammatory mediators when damaged, and also under the influence of antibody
- By increasing vascular permeability, inflammation allows complement and cells to enter the tissues from the blood
⇒ Innate immune system
17
Q
What is a PMN (polymorphonuclear leucocyte)?
A
- 80% of the white cells in the human blood
- Short-lived scavenger blood cell whose granules contain powerful bactericidal enzymes
- Peculiar shaped nuclei
- Comes from the bone marrow
⇒ Innate immune system
⇒ Classed as a myeloid cell
18
Q
What are macrophages?
A
- Large tissue cell responsible for removing damaged tissue, cells, bacteria, etc
- Comes from the bone marrow
⇒ Innate immune system
⇒ Classed as a myeloid cell
19
Q
What are dendritic cells?
A
- Present antigens to T cells
- Initiate all T-cell-dependent immune responses
⇒ Innate immune system
20
Q
What is phagocytosis?
A
- ‘Cell eating’
- Engulfment of a particle by a cell
- Macrophages and PMNs are the most important phagocytic cells
- The majority of foreign materials entering the tissues are ultimately disposed of by this mechanism
⇒ Innate immune system
21
Q
What is cytotoxicity?
A
- Macrophages can kill some targets (perhaps including tumour cells) without phagocytosing them and there are a variety of other cells with cytotoxic abilities
⇒ Innate immune system
22
Q
What are natural killer cells?
A
- A lymphocyte-like cell capable of killing some targets, notably virus-infected cells and tumour cells, but without the receptor or the fine specificity characteristic of true lymphocytes
⇒ Innate immune system
23
Q
What are antigens?
A
- A substance that stimulates the production of antibodies
- Term applied to any type of adaptive immune response
- Foreign and either particulate (e.g. cells, bacteria) or large protein or polysaccharide molecules
⇒ Adaptive immune system
24
Q
What is specificity?
A
- Denotes the production of an immune response more or less selective for the stimulus, such as a lymphocyte that responds to, or an antibody that fits a particular antigen
⇒ Adaptive immune system
25
Q
What is a lymphocyte?
A
- A small cell found in blood, from which it recirculates through the tissues and back via the lymph, policing the body for non-self material
- Its ability to recognise individual antigens through its specialised surface receptors and to divide into numerous cells of identical specificity and long lifespan makes it the ideal cell for adaptive responses
- Two major populations of lymphocytes: T and B cells
⇒ Adaptive immune system
26
Q
What are B lymphocytes?
A
- Secrete antibodies, the hum oral element of adaptive immunity
⇒ Adaptive immune system
27
Q
What is an antibody?
A
- Major fraction of serum proteins, often called immunoglobulin
- It is made up of a collection of very similar proteins each able to bind specifically to different antigens, and resulting in a very large repertoire of antigen binding molecules
- Antibodies can bind to and neutralise bacterial toxins and some viruses directly but they also act by opsonisation (attachment and labels for immune system) and by activating the complement on the surface of invading pathogens
⇒ Adaptive immune system
28
Q
What are T lymphocytes?
A
- T = thymus derived
- Further divided into subpopulations that ‘help’ B lymphocytes, kill virus infected cells, activate macrophages and drive inflammation
⇒ Adaptive immune system
29
Q
What is opsonisation?
A
- A phenomenon whereby antibodies bind to the surface of bacteria, viruses and other parasites, and increase their adherence and phagocytosis
- Antibodies also activate complement on the surface of invading pathogens
- Adaptive immunity thus harnesses innate immunity to destroy many microorganisms
30
Q
What is the complement?
A
- The complement is often activated by the antibody bound to microbial surfaces
- Binding of a complement to antigen can also greatly increase its ability to activate a strong and lasting B-cell response
- Once activated the complement can damage some cells and initiate inflammation
- Some cells possess receptors for complement which can assist the process of phagocytosis
- An example of reverse interaction between adaptive and innate immune reaction
