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BIOSCI 107 Part Two > Blood and Immune: Cellular Immunity and Histocompatibility > Flashcards

Blood and Immune: Cellular Immunity and Histocompatibility Flashcards

(81 cards)

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1
Q

Where do T lymphocytes mature

A

the thymus

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2
Q

where do the precursor of T cells get produced before migrating to the thymus

A

bone marrow

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3
Q

What is a thymocyte

A

Immature T cell found in the thymus

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4
Q

The coreceptors (cell surface markers) on a T cell

A

CD4+, CD8+ (or just CD4 and CD8)

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5
Q

What is the name for a T cell expressing both CD4 and CD8 on its surface

A

a double positive immature thymocyte

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6
Q

Name of T cells that only express CD4+

A

CD4+ helper T cells

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7
Q

Name of T cells that only express CD8+

A

CD8+ cytotoxic T cells

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8
Q

What % of T lymphocytes in blood are CD8+ + cytotoxic

A

20%

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9
Q

What % of T lymphocytes in blood are CD4+ helper

A

80%

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10
Q

The four subgroups of CD4 T helper cells

A

Treg, Th1, Th2, Th17

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11
Q

What is the function of Tregs

A

to regulate immune response

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12
Q

What is the function of Th1

A

drive cellular response

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13
Q

What is the function of Th2

A

drive antibody response (B cells)

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14
Q

What is the function of Th17

A

control inflammatory response

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15
Q

If a pathogen demands a cellular immune response, which T helper cell subgroup will predominate?

A

Th1

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16
Q

How are T cells distinguished

A

by their antigen (CD4 or CD8)

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17
Q

What is CD in CD4 and CD8

A

cluster differentiation

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18
Q

How can T cells be marked

A

by the monoclonal antibody that binds to the antigen CD4 or CD8

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19
Q

When is the thymus at its largest size and why

A

largest at birth then shrinks with age (cellular immune response developed before and just after birth)

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20
Q

What is the function of the thymus

A

Location where T cells are ‘educated’ to recognise self MHC molecules and where they become CD4 or CD8 (its important in immune response development)

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21
Q

Where is the thymus located

A

It sits at the top of the pericardium above the heart

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22
Q

Name of precursor to T lymphocytes

A

Hematopoietic lymphoid precursors

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23
Q

What is negative selection

A

when T cells die from “neglect”, have not recognised the correct antigen to activate and undergo mitosis

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24
Q

What is positive selection

A

Some cells recognise the correct antigen but are activated too strongly which are killed by apoptosis

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25
What is Apoptosis
is a form of programmed cell death, or “cellular suicide
26
What happens to T cells that survive the thymus
“educated” to recognise self MHC molecules expressed in thymic tissue
27
What system is MHC important for
adaptive immune response/system
28
What type of pathogens are viruses
intracellular
29
Where do viruses replicate
inside cells
30
What do T cells do when they recognise infected cells
either kill them or provide help to other cells that reduce the ability of the virus to replicate and produce copies of itself which infect other cells
31
What does MHC stand for
Major Histocompatibility Complex
32
What is MHC
A set of highly polymorphic genes that code for Human Leukocyte Antigens on the cell surface
33
What antigen on a cell will express parts of a virus if infected
MHC
34
What antigen controls tissue transplantation
MHC
35
What is and isn't "self"
MHC, "not self" is if MHC changed (due to virus or bacteria)
36
What does CTL stand for
Cytotoxic T lymphocytes (CD8 T cells)
37
Function of CTL
stimulate immune response which actively kills cells
38
What do CTL generate?
perforin molecules that are inserted into target cells to kill them
39
What do CTL do if they recognise a "non-self cell"
CTL binds tightly to cells that have altered class 1 MHC (expressing a neo-antigen that is viral or altered self antigen) and release perforin molecules which form pores into target cells causing the release of internal innards of the cell = cell death
40
What is a neo-antigen
are mutated antigens specifically expressed by tumour tissue and are not expressed on the surface of normal cells
41
meaning of congenic
Strains that are genetically identical except for one or more MHC locus/loci
42
What are congenic mice
Congenic mice is when you isolate particular genes that regulate certain phenotypes (e.g. tissue rejection)
43
What is MHC restriction
The fact that a T cell can interact with a self-MHC molecule and a foreign peptide bound to it, but will only respond to the antigen when it is bound to a particular MHC molecule
44
viral immunity requires both these antigens
``` SELF Antigen(s) encoded by MHC NON-SELF Antigen(s) encoded by the virus ```
45
what is HLA
human leukocyte antigen coded for by MHC
46
What does a T cell form with a target cell?
synapse so it can insert signal into target cell so it undergoes apoptosis
47
How is MHC changed by a target cell
MHC has been changed because of a new peptide antigen that has been inserted into groove on the top of the MHC (HLA) molecule
48
What a T cell receptor
a membrane bound Ig-like molecule on T lymphocytes
49
Classes of MHC
class 1 and 2
50
Names of antigen/loci in class 1
A, B and C
51
Names of antigen/loci in class 2
DR, DP, DQ
52
How many types of each antigen in both class 1 and 2 exist
two possible types (paternal and maternal alleles)
53
How many types of antigens in total are expressed on the surface of cells
12
54
What does H2 refer too
the MHC antigens on mouse cells
55
What can MHC molecules be used for in medicine
you can transplant and store tissues in case someone needs a bone marrow transplant
56
What part of MHC class 1 is polymorphic
the top (the 2 alpha helices on top of the heavy chain), amino acid sequences vary from individuals
57
Where does a viral peptide sit in MHC class 1
in groove between the two alpha helices
58
What part of MHC class 1 is invariant
lower part (bound by CD8)
59
What holds MHC class 1 molecules in the right conformation
Beta 2M
60
What part of MHC class 2 is polymorphic
The top (1 beta and 1 alpha strand)
61
Where does a viral peptide sit in MHC class 2
in groove between alpha and beta strand
62
Is the viral peptide longer in class 1 or 2
class 2
63
Where does viral peptide come from in MHC class 1
from virus inside the cell or altered self antigen
64
Where does viral peptide come from in MHC class 2
antigens that have come from extracellular pathogens like bacteria that have been taken up by phagocytosis and broken down so pieces attach groove
65
What type of cell recognises antigens in MHC class 1
CD8 cytotoxin T cells
66
What type of cell recognises antigens in MHC class 2
CD4 Helper T cells
67
What is intracellular tyrosine kinases
CD8 and CD4 have these receptors associated with their cytoplasmic tails. These initiate T cell signalling through phosphorylation
68
What do CD4+ T Helper cells do when they recognise MHC class 2 antigens
T cells proliferate and produce cytokines that "help" other cells
69
What do CD8+ T Helper cells do when they recognise MHC class 1 antigens
CTL produces granzyme and perforins that punch holes in the target cell membrane and destroy cell viability
70
Type of pathogen antigen expressed by MHC class 1
virus
71
Type of pathogen antigen expressed by MHC class 2
bacteria
72
Peptide source in MHC class 1
intracellular
73
Peptide source in MHC class 2
extracellular
74
What is polymorphism
genes that encode for the MHC complex are all different across individuals
75
Is tissue rejection learned
yes
76
What are haplotypes
a set of genetic determinants located on a single chromosome (lots of differing variations of aa sequence at each MHC locus)
77
What is polymorphism restricted to
the protein domains that form the peptide groove
78
What are anchor amino acids
the few points in peptides that are invariant (amino acid side chains point down into MHC molecule and anchor)
79
What is the evolutionary purpose of polymorphism in MHC
Polyphormism is designed to create the broadest capacity for protection of a species as a whole (MHC in a community is for what they are most likely to encounter). When communities do not have the right MHC haplotypes, new diseases can devastate communities
80
Two major consequences of MHC polymorphism
Tissue transplantation and autoimmune diseases
81
What did the congenic mice experiment show
viral immunity requires both self MHC and foreign antigen

BIOSCI 107 Part Two (17 decks)

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