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IBI Test 1 > B3.084 T Cell Development > Flashcards

B3.084 T Cell Development Flashcards

1
Q

what types of cells do blood cells arise from?

A

a common pluripotent stem cell

hematopoietic stem cell

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2
Q

what are the 3 classes that cells differentiate into during early development?

A

erythroid progenitors (RBCs and platelets)
myeloid committed precursor cells
lymphoid committed precursor cells

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3
Q

what types of cells are made from lymphoid precursors?

A

T cell
B cell
dendritic cell
NK cell

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4
Q

what types of cells are made from myeloid precursors?

A 
dendritic
monocytes
neutrophils
eosinophils
basophils
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5
Q

how long do neutrophils survive in blood?

A

days or weeks

shorter once recruited to tissues

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6
Q

how long do lymphocytes live in blood?

A

years

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7
Q

characterize leukocytes

A

white blood cells
responsible for innate and adaptive immune responses
originate in bone marrow
recognize and destroy foreign invaders

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8
Q

how do NK cells differ from B and T lymphocytes?

A

do not possess antigen receptors
have some similar qualities to T cells despite this
use antibody to recognize antigen
more a part of the innate immune system

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9
Q

what would happen if clonal selection was uncontrolled?

A

you would develop a tumor

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10
Q

what is one way clonal selection is regulated?

A

T cells kill B cells

make you feel bad, but prevent you from developing tumors

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11
Q

what are the two types of antigens MHC molecules can present?

A

self antigen - ALL THE TIME, do not elicit a response
foreign antigen - when there is an infection
self MHC + foreign antigen = T cell recognition

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12
Q

can a T cell respond to a non-self MHC?

A

no
only self MHC
different in everyone

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13
Q

what important parts of the immune system are encoded within the human MHC gene on chromosome 6?

A 
Class 2 - DP,DQ,DR
Complement C4, C2
TNF
Class 3
Class 1 - B,C,A
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14
Q

what cytokines can increase cell surface levels of MHC class 1?

A

IFN- a,b, gamma

antiviral state

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15
Q

what cytokines can increase cell surface levels of MHC class 2?

A

IFN gamma

TNF alpha

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16
Q

what does it mean to say that MHC antigens are codominant?

A

each allele inherited from the parent is expressed

17
Q

how do TCR and BCR exhibit allelic exclusion?

A

the product of only one chromosome is expressed

nothing in common with parents due to somatic recombination

18
Q

what is a haplotype

A

combination of alleles at linked loci found on one chromosome
often used with reference to the MHC

19
Q

polymorphism

A

existence of multiple alleles at a particular gene locus

20
Q

how many different MHC class 1 molecules does each individual possess?

A

6

21
Q

why can each individual have many MHC class 2 molecules?

A

individual a chains can pair with individual b chains

22
Q

describe the process of MHC binding and presenting

A

MHC molecules bind to an antigen
this sits in a cleft within the molecule
antigen within the cleft is presented to T lymphocytes
antigen binds to MHC with broad specificity
antigen binds to TCR with precise specificity

23
Q

what occurs as T cells pass from immaturity through maturity in the thymus?

A

develop TCRs

other surface molecules change (CD3, CD4, CD8)

24
Q

does the T cell develop further after leaving the thymus?

A

no

25
Q

which complex does the TCR require to function?

A

CD3

26
Q

what is an indicator of a stem cell in the bone marrow?

A

CD34+

27
Q

describe the stages of T cell development

A
  1. CD3+ and CD4 - CD8 -
  2. CD3 + and CD4 + CD8 + (DP)
  3. CD3+ and either CD4+ or CD8+ (SP) (1.7:1 ratio of CD4+:CD8+)
28
Q

negative selection

A

getting rid of T cells that respond to self antigen presented by MHC

29
Q

positive selection

A

select for functioning T cells that are able to bind to self MHC complexes

30
Q

central tolerance

A

occurs in the thymus

cells that respond strongly to self MHC and self antigen are destroyed

31
Q

peripheral tolerance

A

outside of the thymus

occurs when self reacting T and B cells are in an unreactive state to self antigens

32
Q

what are the 4 mechanisms of peripheral tolerance?

A
  1. ignorance - autoreactive T cells never encounter their cognate Ag except by accident
  2. Deletion - self-specific peripheral T cells are destroyed after TCR engagement (negative selection is leaky and some T cells survive until later)
  3. Anergy - a state of functional unresponsiveness induced upon self Ag recognition
  4. Foxp3+ Treg cell mediated suppression of dangerous T cell responses against self-Ag
33
Q

how are Treg cells produced?

A

stimulation of CD4+ T cells with TGFB

34
Q

how do Treg cells inhibit T cells?

A

cytokines IL-10 and TGFB

IBI Test 1 (15 decks)

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