10. IMMUNITY Flashcards
1
Q
All macrophages and neutrophils arise from a stem cell called the
A
haematopoietic stem cell
2
Q
What are granules in neutrophils
A
secretory vesicles
3
Q
The cytoplasm of a neutrophil contains vacuoles full of
A
hydrolytic enzymes
4
Q
What removes dead cells in the body
A
Phagocytes (have lysosomes and vacuoles with hydrolytic enzymes)
5
Q
Why is it hard to develop a vaccine for malaria
A
- several causative species
- has many antigens as it is eukaryotic
- different antigens in different stages of life
- mutations change antigens/antigenic mutation/variation
- antigenic concealment
6
Q
Why would a vaccination programme be unsuccesful
A
- not able to achieve herd immunity
- lack of willingness of people to get vaccinated
- lack of trained people to vaccinate
- poor immune response
- only trial programmes
7
Q
How are monoclonal antibodies made by hybridomas
A
- protein injected into mouse and time given for immune response to occur
- plasma cells extracted from mouse spleen and fused with cancer cells forming hybridoma cells
- cells are separated and cultured in individual wells
- screened for cells producing desired antibody and grown in large cell culture
- antibodies produced can be humanised
8
Q
Why do we suffer repeated infections of influenza or the common cold
A
- because there are many different strains of viruses that cause these diseases
- each with having different antigens
9
Q
Neutrophils (granulocytes)
A
- phagocytes
- form 60% of the white cells in the blood (most common)
- travel throughout the body, often leaving blood by squeezing through gaps in the walls of the capillaries
- are released in large numbers from their stores in the bone marrow during an infection
- short-lived cells
- contain many lysosomes/vesicles
- number of neutrophils in the blood increase during bacterial infections and when cells become inflamed and die
- smaller than macrophages/monocytes
10
Q
Macrophages (agranulocytes)
A
- phagocytes
- larger than neutrophils
- tend to be found in organs such as the lungs, liver, kidneys, spleen and lymph nodes, rather than remaining in the blood
- travel in the blood as monocytes, which develop into macrophages once they leave the blood and settle in organs, removing any foreign matter found there
- long-lived cells
- play a crucial role in initiating immune responses as they act as APCs
11
Q
What is histamine
A
- when pathogens invade the body, some of the body’s cells under attack respond by releasing histamine
- plays a role in chemotaxis
12
Q
What is chemotaxis
A
movement towards a chemical stimulus such as histamine or other chemicals released by pathogens when they invade the body is called chemotaxis
13
Q
Plasma cells
A
- produced by B lymphocytes
- make antibodies
- contain large network of rough endoplasmic reticulum for the production of antibody molecules (protein synthesis)
- contain many mitochondria to provide ATP for protein synthesis and the movement of secretory vesicles
14
Q
Why are several antibiotics taken
A
- bacteria likely to be resistant to one antibiotic
- bacteria less likely to be resistant to all antibiotics
15
Q
Why are antibiotics taken over a long period of time
A
- bacteria are inside cells where they are protected from antibiotics
- bacteria grow/divide slowly
- ensures all bacteria are killed, otherwise they remain
- prevents development of antibiotic resistance
16
Q
What causes difference in blood groups
A
- glycolipid antigens on red blood cells
17
Q
Functions of cytokines
A
- stimulate appropriate B cells to divide by mitosis, differentiate into plasma cells, and secrete antibodies
- stimulate macrophages to carry out phagocytosis more vigorously
- stimulate appropriate killer T cells to divide by mitosis and differentiate by producing vacuoles full of toxins
18
Q
What does the interaction between acetylcholine and its receptors do
A
- it stimulates channels to open allowing sodium ions to move through the membranes
- the influx of sodium ions begin a series of events that result in muscle contraction
19
Q
How is myasthenia gravis an autoimmune disease
A
- people with MG have helper T cells specific for the cell surface receptors for acetylcholine
- these cells stimulate a clone of B cells to divide and differentiate into plasma cells and secrete antibodies
- which bind to the receptor blocking the transmission of impulses from motor neurones
20
Q
What happens to muscle cells without receptors for acetylcholine
A
- muscle cells are not stimulated
- without any stimulation, muscle tissue starts to break down
21
Q
Symptoms of myasthenia gravis
A
- muscle weakness that gets worse with activity and improves with rest
- drooping eyelids are an early symptom
22
Q
Why are drooping eyelids one of the first symptoms of MG
A
these muscles are in constant use and tire quickly
23
Q
Treatments for myasthenia gravis
A
- a drug that inhibits the enzyme in synapses that breaks down acetylcholine
- this increases the concentration of acetylcholine in synapses so its action in stimulating muscle fibers to contract lasts for longer
- surgical removal of the thymus gland
- because it is the site of maturation of the helper T cells that stimulate B cells to produce antibodies to the acetylcholine receptors
24
Q
Names of autoimmune diseases
A
myasthenia gravis
multiple sclerosis
rheumatoid arthritis
type-I diabetes
25
What happens in multiple sclerosis
- nerve cells in the brain and spinal cord lose the insulating myelin sheaths that surround them
- can happen anywhere in the CNS and appears to be quite random
- degenerating areas, known as plaques, can be detected using MRI scans
- with the loss of the protective myelin, the neurones stop conducting impulses
- and there is a loss of the functions controlled by the areas of the CNS concerned
26
Symptoms of multiple sclerosis
- muscle weakness
- loss of sensory output from the skin and other areas
- poor vision
- mental problems
27
What is rheumatoid arthritis
- starts with the finger and hand joints and spreads to the shoulders and other joints
- tendons become inflamed and there is constant muscle spasm and pain
- people with rheumatoid arthritis find it hard to keep mobile
28
What is type 1 insulin-dependent diabetes
- caused partly by a virus infection that makes the cells that secrete insulin in the pancreas unrecognisable as self
- killer T cells enter the islets of Langherhans and destroy the cells that produce insulin
29
Why do some autoimmune diseases like myasthenia gravis run in families
- it is not an inherited condition
- people with certain alleles of genes involved in cell recognition are at a higher risk of developing MG than those without those alleles
- susceptibility to the diseases is inherited
30
Why are antibodies desirable in the treatment and diagnosis of disease
they are very specific
31
What is the problem in making monoclonal antibodies
- B cells that divide by mitosis do not produce antibodies
| - plasma cells that produce antibodies do not divide by mitosis
32
How are radioactively labelled antibodies made
a radioactive chemical that produces gamma radiation is attached to each antibody molecule
33
How are radioactively labelled antibodies used in diagnosis
- can be used to locate the position of blood clots in the body of a person thought to have deep vein thrombosis
- labelled antibodies are introduced into the patient's blood
- as the antifibrin Mabs are carried around the body, they bind to any fibrin molecules with which they come into contact
- a gamma-ray camera is used to detect the radioactivity emitted by the labelled antibodies and locate their exact position
- the position of the labelled Mabs indicates the position of any blood clots
34
How are Mabs humanised so they can be used in treatment
- altering the genes that code for the light and heavy chains of amino acids so that they code for human sequences of amino acids, rather than mouse or rabbit sequences
- changing the type and position of the sugar groups that are attached to the heavy chains to the arrangement found in human antibodies
35
What can be diagnosed by monoclonal antibodies
- location of blood clots in a person thought to have deep vein thrombosis: antifibrin antibodies bind to fibrin which is the main protein found in blood clots
- locate cancer cells: cancer cells have proteins in their cell surface membranes that differ from the proteins on normal blood cells and can therefore be detected by antibodies
- identify the exact strain of a virus or bacterium that is causing an infection: this speeds up the choice of the most appropriate treatment for the patient
- blood typing for transfusion
- tissue typing before transplants
36
Advantages of using monoclonal antibodies in diagnosis
- monoclonal antibodies used all have the same specificity
- detect only one antigen
- can distinguish between different strains of pathogens
- can be labelled
- can detect location of cancer cells
- faster diagnosis
37
What is the advantage of herd immunity in a population
- interrupts transmission in a population
| - so that those who are susceptible never encounter the infectious agents concerned
38
What is the virus that causes the common cold
rhinovirus
39
Diseases caused by protoctists
malaria
| sleeping sickness
40
Effects of leukaemia
- anaemia and risk of excessive bleeding
| - more susceptible to infection/immunosuppressed
