Karteikarten
How does the immune system recognise pathogens?
Karten in diesem Stapel (35)
- 1What two things must the immune system do? What are the consequences if they are not done?recognise and respond to pathogens
-death from infectious diseases
not respond to component of our own bodies
Paul Ehrlich - 'horror autoxicus' -not possible
-auto-immune disease - 2What is an antigen?anything that binds to a specific receptor on an immune cell
pathogens contain many antigens - 3What is an immunogen?anything that elicits an immune response
most (but not all) antigens are immunogens - 4What is an epitope?the portion of an antigen that is recognised and bound by a receptor on an immune cell
- 5Can you give an overview of antigen recognition?receptor binds to antigen
signalling cascade initiated
(changes what cell does)
gene transcription
production of effector molecules - 6Give some examples of cells that can be found in the adaptive and innate immune systemadaptive
-T cells, B cells
innate
-NK cells, monocytes/macrophages, granulocytes, dendritic cells - 7In terms of antigen recognition what is the difference between the innate and adaptive immune system?innate
-few antigens can be recognised
adaptive
-millions+ of antigens recognised - 8Briefly describe the recognition of 'non-self' by innate immune cellspattern recognition receptors (PRRs)
recognise
pathogen associated molecular patterns (PAMPs)
which aren't present in host cells e.g. cell wall, flagella - 9With innate immune cells there is an inherent lack of response to self (tolerance). Why is this?because the things the receptors recognise are absent from our bodies
- 10What is an important example of pattern recognition receptors?Toll-like receptors
13 in mice
10 in humans - 11Describe the general process of adaptive immunity - how are large numbers of useful cells generated in response to an antigen?millions of different antigens to be recognised
each new lymphocyte expresses just one type of receptor and recognises one antigen (specific)
only a few of each of these lymphocytes
antigen activates lymphocyte with 'right' receptor
clonal expansion of these lymphocytes - 12Explain the recognition of B cells including the following key terms: Ig, BCR, epitope, antibodyARM used by B cell = immunoglobulin (Ig)
membrane bound Ig = B-cell receptor (BCR)
antigens recognised directly
shape of epitope formed by protein folding
B cell is activated
and differentiates into plasma cells
which secrete Ig (antibody)
with specificity identical to BCR - 13Describe the structure of a typical antibody - draw and label a diagram2 heavy chains (long)
2 light chains (short)
^identical to each other
constant region - doesn't differ between different antibody molecules
variable region - specific to antigen - where antigen binds
structure held together by disulphide bonds - 14B cells can make different classes (isotypes) of antibody. What is the benefit of this?each antibody class can mediate different biological functions
allows immune system to activate different immune mechanisms that may be more tailored to a specific problem - 15What are the different classes of antibody? Comment on their structureIgM - pentamer
IgE - monomer
IgG - monomer
IgA - dimer - 16What special process can B cells undergo?a given B cell starts by making IgM but then switches to making IgG or IgA or IgE
this is known as class switching - 17During the process of class switching what remains constant and what changes?antibody specificity remains constant
biological effector functions vary - 18Which class of antibody is made first in an immune response? What happens next? What do the different levels of each type of class indicate? Include a diagram in your answerIgM
class switching
primary then secondary IgG made
loads of IgM = recent infection
loads of IgG = happened long time ago - 19With B cells how is receptor diversity generated? Explain in detail and include a diagram in your answerby random mixing and matching of variable, diversity and joining segments within the heavy chain and light chain loci
known as somatic DNA recombination
-B cell in bone marrow
some DNA spliced out
DJ recombination
more splicing, V-DJ recombination
transcription to make mRNA
RNA splicing to make mature transcript
translation and assembly of light and heavy chains - 20How do T cells recognise antigens?using a T cell receptor (TCR)
antigen presenting cell
e.g. dendritic cell, macrophage
present antigen to T cell
using major histocompatibility complex
linear (peptide) antigens are recognised - 21Draw a diagram depicting the structure of the T Cell receptor (things to include is on answer flashcard)a chain
b chain
carbohydrate
variable region
constant region
stalk segment
transmembrane region
cytoplasmic tail
disulfide bond - 22When do T cells being to express TCRs?during their development in the thymus
- 23The generation of TCR diversity also involves....somatic DNA recombination
- 24Define the term major histocompatibility complexthe major genetic region that determines compatibility of tissues transplanted between individuals
(whether or not tissues would be accepted or rejected) - 25Define the term HLAhuman leukocyte antigens
name given to MHC molecules in humans - 26What are the two different types of MHC? What is the difference between them?MHC Class I
-found in all cells
-present antigen to CD8 cytotoxic T cells
MHC Class II
-found in APC only
-present antigen to CD4 helper T cells - 27What can be said about the peptide binding by MHC molecules?peptide binding by MHC molecule is
PROMISCUOUS
bind to a range of peptide that can be accommodated in the groove
(so not a specific peptide) - 28What determines the binding between MHC molecules and the linear peptide antigens?the fit between amino acid side chains in the peptide and pockets in the groove of the MHC molecule
- 29The MHC has two properties that help ensure the maximum number of peptides can be presented. What are they?polygenic
-more than on type of MHC class I and class II molecule
highly polymorphic
-multiple alleles in population means most people are heterozygous - 30One of the two major properties of MHCs may prove a barrier to organ transplantation. Which property is this and how does this act as a barrier?polymorphism
different MHC molecules on the graft are recognized as foreign
tissue rejected due to immune response - 31Explain the immunology of Coeliac disease. How common is the disease and what is it specifically?occurs in people carrying particular MHC class II molecules
-HLA-DQ2 or HLA-DQ8
only these MHC molecules can present gliadin peptides in gluten to T cells to cause disease
relatively common 1:200 Caucasians
chronic inflammation of small intestine
due to inappropriate immune response to wheat gluten - 32What is central tolerance?as T cells develop in the thymus and B cells in the bone marrow, their receptors are tested for reactivity to self antigens
-if self-reactivity is too strong the lymphocytes are killed - 33What is peripheral tolerance?self-reactive lymphocytes that escape deletion during development can be controlled in the periphery by regulatory T cells - Treg
- 34What is tTG and what does it do?enzyme tTG (tissue transglutaminase)
modifies proteins
deanimates glutamine to form glutamic acid
when done in gliadin derived peptides increases their ability to bind to HLA-DQ2
example of positive reinforcement
T cell activated produces lots of cytokines - 35What are three histological features of coeliac disease?villus atrophy
crypt abscesses
intraepithelial lymphocytes
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- University Fundamentals of Medicine (Immunology) Karteikarten am How does the immune system recognise pathogens?, erstellt von Ifeoma Ezepue am 01/11/2015.
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