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week 18 > the patient > Flashcards

the patient Flashcards

1
Q

explain in detail B cell development

A

repertoire assembly: generation of diverse on clonally expressed B cell receptors in the bone marrow

negative selection: alteration, elimination, or in activation of B cell that bind to the components of the human body

Positive selection: promotion of a fraction of immature B cells to become mature B cells in the secondary lymphoid tissues

Searching for infection: recirculation of mature B cells between the lymph , blood, and secondary lymphoid tissues

Finding infection: activation, and clonal expansion of B cells by pathogen derived antigens in secondary lymphoid tissues

Attacking infection: differentiation to antibody, secreting, plasma, cells, and memory B cells in the secondary lymphoid tissue

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2
Q

what is B cell development coupled with?

A

BCR expression

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3
Q

What happens when an immature B cell in the bone marrow has no reaction with a self antigen

A

immature B cell moves to the blood and expresses IgD and IgM

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4
Q

what happens when an immature B cell in the bone marrow reacts with a self antigen

A

The immature B cell in the bone marrow

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5
Q

why are self reactive B cells edited

A

self antigen lignite’s immature B cells IgM

The immature B cell continues to rearrange light chain genes

if the new receptor is self reactive: light chain genes continue rearranging. successive new receptors are self reactive. No further rearrangements all possible and the immature B cell undergoes apoptosis

If the new receptor is not self reactive: the B cell leaves the bone marrow

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6
Q

what is the fate of weakly self reactive cells

A

IgM of immature B cell binds soluble univalent self antigen

B cell is signaled to make IgD and to become unresponsive to antigen

Dissenters the peripheral circulation, but does not survive so long

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7
Q

what is receptor editing

A

live

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8
Q

what is apoptosis

A

die

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9
Q

what is anergy

A

love for a short time

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10
Q

what are the 3 self reactive fates that a B cell has

A

receptor editing
Apoptosis
anergy

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11
Q

Where in the body is central tolerance

A

In the bone marrow

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12
Q

Where in the body is preferable tolerance

A

in the tissues

No receptor editing - encounter self antigen, = die by apoptosis

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13
Q

what is the tolerance of B cells?

A

There is no perfect tolerance, some self antigens are in accessible normally. Revealed after infection or trauma.

self reactive B cells may be released that will respond to these

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14
Q

what do B cells do when they mature

A

They leave the bone marrow and circulate looking for Ag and T cell help

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15
Q

what do chemokines do

A

attract B cells to LN to primary follicle

CCL21
CCL21
CCL19
CXCL13 attracts B cell to the primary follicle

interactions with follicular Dedrick cells on cytokines drive the maturation of immature B cells

Mature B cells recirculate than recirculate between the lymph, blood, and secondary lymphoid tissues

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16
Q

what causes activation

A

B cell + Th + Ag

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17
Q

What do germinal centers do?

A

Class switch
Mutation to optimize antibody

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18
Q

What do plasma cells do?

A

secrete antibodies
Antibody is the same specificity as the surface of Ig of B cells

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19
Q

what do memory cells do?

A

To be ready for the future

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20
Q

What does neutralizing antibodies do?

A

it inactivates, pathogens or toxins

To prevent interaction of the pathogen with cells

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21
Q

what do opsonising antibodies do?

A

The coat pathogens

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22
Q

what is agglutination

A

antibodies can immobilize organisms by agglutination

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23
Q

When does lysis of bacteria occur

A

antibodies bound to bacterial success will activate compliment, and this will lead to the lysis of bacteria

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24
Q

what can B cell mediated immunity do

A

can activate NK cells

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25
Q

what does IgM do

A

it immobilizes pathogens
It activates compliment

26
Q

what does IgG do

A

it improves antibody delivery to tissues
It is small and rapidly diffuses

it mediates cell KILLING

The antibodies bind to antigens on the surface of the target cell

Fc receptors on NK cells recognize the bound antibody

Cross-linking of Fc receptors signal the NK cell to kill the target cell

Target cell dies by apoptosis

27
Q

what does monomeric IgA do

A

It supports IgG

28
Q

what does FcRn do

A

It transports IgG across the endothelium via endocytosis

The acidic pH of the endocytic vesicle causes the association of IgG and FcRn protecting it from proteolysis

On reaching the basolateral face of the endothelial cell the basic pH of the extracellular fluid disassociate IgG from FcRn

29
Q

what does dimeric IgA do

A

it protects mucosal sites

binding of IgA to receptor in basolateral face of epithelial cell

receptor mediated endocytosis of IgA

Transport of IgA to apocalypse face of the epithelial cell

Receptor is cleaved, IgA is bound to mucus through the secretory piece

30
Q

what does IgE do

A

allows for rapid ejection of pathogens and allows for large parasite defense

binds to an Fc receptor on mast cells

awaits pathogen

cross-linking activates mast cell degranulation

31
Q

How can an antibody neutralize?

A

It prevents the adhesion of bacteria to host cells and toxins to receptors

32
Q

What can an antibody due to the classical cascade?

A

It’s can activate complement and fix complement

33
Q

how do Fc receptors permit Ig opsonised uptake

A

The antibody binds to the bacterium

The antibody coated bacterium binds to Fc receptors on the cell surface

Macrophage membrane surrounds bacterium

Macrophage, membranes, fuse, creating a membrane-bound vesicles. [phagosome]

Lysozymes fuse with the phagosome creating the phagolysosome

34
Q

where do T cells mature

A

T cells precursors travel from the bone marrow to develop in the thymus

Mature T cells leave the thymus and travel to secondary lymphoid tissues

35
Q

What two main constituent is the famous made up of

A

Cortex and medulla

36
Q

how many checkpoints are there for T cells

A

2

37
Q

what type of rearrangement comes first in T cell formation

A

B chain rearrangemen

Successful a chain rearrangement ensures a/b T cells are formed

y/s rearrangements happen at the same time as the B chain

38
Q

what is positive selection?
DP T cell screening

A

positive selection of a/b T cell by the cortical epithelial cells in the thymus

39
Q

what is negative screening/selection of T cells
DP T cell screening

A

negative selection of a/b T cells by dendritic cells, macrophages, and other cells in the thymus

40
Q

what is the third type of T cell

A

CD4+

it is a regulatory T cell

It’s protects against imperfect selection of T cells

Suppression of auto reactive T cells by regulatory T cells require them to interact with the same antigen presenting cells

41
Q

What is priming?

A

it is the activation of naïve T cells

Primary immune response

42
Q

Where are immune responses, concentrated?

A

In the secondary lymphoid tissues

43
Q

what do dendritic cells do

A

dendritic cells, take up, bacterial antigens in the skin, and then move to enter a draining lymphatic vessel

Dendritic cells, bearing antigen enter the draining lymph node. Where they settle in the T cell areas.

They also change function to be more effective(peripheral tissues, lymphatic circulation, lymphoid, tissues.]

44
Q

what do naive cells need to be activated

A

co stimulation

45
Q

how can naive T cells enter lymph nodes from the blood

A

T cells enter a lymph node across high endothelial venules in the cortex

T cells monitor antigen presented by macrophages and dendritic cells. [when they enter a lymph note.]

T cells that do not encounter specific antigen leave the node in the efferent lymph

T cells that encounter a specific antigen proliferate and differentiate to effector cells

46
Q

what does co stimulation prevent

A

self reactivity

Co simulatory signal plus specific signal leads to an activated T cell

when that is only the specific signal alone, this leads to the T cells becoming a ethic (a condition in which the bodies immune system fails to react to an antigen.]

When that is only the co stimulatory signal alone this has no effect on a T cell

47
Q

helper, T cells have different functions

What are some of these?

A

naive CD4 T cell
proliferating T cell
immature effector T cell

Th1 = macrophage activation, B cell activation, and the production of opsonising antibodies.

Th2 = general activation of the cells to make antibodies

48
Q

what is the Th1 response

A

Cell mediated immunity [effector cells]

activated macrophages
Control of bacteria
More limited disease

49
Q

what is the Th2 response

A

Humoral immunity [antibodies]

antibody production
No bacterial control
More spreading of disease

50
Q

what does it mean when the immune response is polarized?

A

The immune system is favoring one type of immune response over others

51
Q

how are effector T cells activated

A

stimulation of a naïve T cell [Ag recognition, and B7 is needed.]

Proliferating T cell [division and differentiation gives effector cells]

An active effector, T cells recognizes and kills the virus, infected target cells [effector cells need only Ag recognition to act]

52
Q

what do CD8 T cells do

A

cytotoxic T cells
Perforate virus, infected cells

53
Q

what do Th1 (CD4) T cells do

A

They have a macrophage containing bacteria

54
Q

what do Th2 (CD4) T cells do

A

they form a B cell presenting a specific antigen

55
Q

how do CD8 T cells work

A

collision a non-specific adhesion

Specific recognition redistributes the cytoskeleton and cytoplasmic components of the T cell

Release of lytic granules at site of cell contact

56
Q

how do cells killed by cytotoxic CD8 T cells die

A

by apoptosis

57
Q

what is the benefit of CD8 T cells

A

cells undergo controlled, programed death.

this prevents replication or release of pathogens

Enhances clearance by phagocytosis

58
Q

What are the two mechanisms for killing?

A

cytotoxins
Death, receptor interactions

59
Q

what are cytotoxins

A

Perforin ,which forms pores and delivers for granzyme to the target cell

initiates apoptosis

60
Q

What are death receptor interactions?

A

Fas-Fas ligand

ligation of Fas on the target cell initiate apoptosis

61
Q

How can we manipulate the immune system by a vaccine?

A

B cell Binds bacterial polysaccharide component of vaccine conjugate

Conjugate is internalized and degraded

Peptides from the toxoid are presented to the T cell, which activates the B cell

activated be so differentiate into a plasma cell, that’s produces anti polysaccharide antibodies that bind to the bacteria

week 18 (3 decks)

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