Immune system 2

Question 1

Primary lymphoid structures

Answer 1

thymus
bone marrow
site of formation, differentiation and maturation of lymphoid cells
no antigen contact

Question 2

Secondary lymphoid structures

Answer 2

spleen
lymph nodes
tonsils & adenoids
Peyer’s patches
contains both T and B cells
Have contact with antigens
Allow initiation of adaptive immune response

Question 3

Humoral immunity

Answer 3

through the blood/humors of the body
protection against extracellular microbes
B lymphocytes and antibodies secreted by B lymphocytes

Question 4

Cell-mediated immunity

Answer 4

protection against intracellular microbes
T lymphocytes

Question 5

Lymphocytes

Answer 5

very specific to antigens but are also very diverse
can migrate to sites of inflammation
lymphocyte classes do not interact with each other unless a stimulus is present (antigen, chemical messengers)

Question 6

Naive cell

Answer 6

mature lymphocyte that has not encountered its specific antigen

Question 7

Effector cell

Answer 7

differentiation of lymphocyte after antigen recognition, functions to eliminate microbes

Question 8

Memory cell

Answer 8

differentiated lymphocyte after antigen recognition, in a state of heightened awareness to more effectively fight microbe if it returns

Question 9

B lymphocytes

Answer 9

produced and mature in the bone marrow
provide humoral immunity
have membrane bound antibodies
once activated –> differentiate into memory B cells and effector cells
professional APC

Question 10

effector B cell

Answer 10

come from plasma cells
produce circulating antibodies

Question 11

If B cells are naive

Answer 11

must have T helper cells and chemical messengers to differentiate and multiply

Question 12

Fab region on antibodies

Answer 12

antigen-binding fragment that contain recognition sites for antigen
contain variable regions that determine antigenc specificity

Question 13

Fc region on antibody

Answer 13

crystalline fragment that is constant, responsible for activation of complement cascade and opsonization
Defines the class of the antibody (IgE, IgG, etc)

Question 14

T lymphocytes

Answer 14

cell mediated immunity
mature in the thymus
once activated: differentiate
T cells cannot recognize antigens directly, T cells recognize antigen peptides presented on MHC

Question 15

T helper cells (Th)

Answer 15

T helper effector cells: release cytokines and raise the alarm bells
have CD4 co-receptors –> bind to MHC 2
attracted to antigens presented that occurred from OUTSIDE of the cell (exogenous)
must be present to fully activate naive B cells (double check)

Question 16

Cytotoxic T cells (Tc)

Answer 16

Tc effector cells: kill bad cells
have CD8 co-receptors –> bind to MHC 1
attracted to antigens presented that occurred from INSIDE the cell (endogenous)

Question 17

regulatory T cells (Treg)

Answer 17

subpopulation of Th cells – controls or limits the immune response, releases immunosuppressive cytokines, suppress antigen recognition

Question 18

Each B or T cells have only a

Answer 18

single receptor specificity and can only recognize one single antigen

Question 19

Generation of clonal diversity primarily occurs in

Answer 19

the fetus

Question 20

Clonal diversity is developed…

Answer 20

before any exposures to antigens occur
occurs primarily in lymphoid organs

Question 21

Where are T cells developed

Answer 21

liver in fetus
bone marrow in adults

Question 22

Central tolerance for T cells

Answer 22

the deletion of auto-reactive T cells within the thymus

Question 23

TCR that respond to self antigens are considered

Answer 23

auto reactive T cells

Question 24

Clonal deletion

Answer 24

a T cell undergoes apoptosis during maturation in the thymus

Question 25

Positive selection

Answer 25

process by which T cells are screened so that only those capable of binding to MHC are kept alive

Question 26

Negative selection

Answer 26

the process by which T cells are screened so that those with a high affinity for binding to self antigens (and potentially causing autoimmunity) are destroyed

Question 27

AIRE

Answer 27

autoimmune regulation = transcription factor
produced by medullary thymus epithelial cells and controls synthesis of self proteins found in periphery
allows expression of tissue-specific self antigens (TSAs) within the thymus medulla

Question 28

Peripheral tolerance in T cells

Answer 28

the deletion or anergy of lymphocytes that recognize self antigen in peripheral tissue

Question 29

Types of peripheral tolerance

Answer 29

Ignorance
Suppression
Anergy
Activation induced cell death

Question 30

Ignorance in T cells

Answer 30

T cell does not have opportunity to come in contact with antigen – held captive in lymph

Question 31

Suppression of T cells

Answer 31

t-regulatory cells is important in dampening the immune response

Ex: secretes cytokines IL-10 and TGF-beta

Question 32

Anergy of T cells

Answer 32

normal cell will not have co-stimulatory signal that an APC has

Ex: no B7 co-stimulation or Ag may not be presented within MHC

no cytokine activity from innate immune system

Question 33

Activation induced cell death

Answer 33

cell is activated repeatedly and induce apoptosis

Ex: reactivated cells induce Fas/FasL binding –> self apoptosis

This occurs mainly to cytotoxic T cells

Question 34

Central tolerance for B cells

Answer 34

in bone marrow

reactive B cells to self antigens undergo Ag receptor gene rearrangement

‘try again’ method

if this fails –> apoptosis

Question 35

Peripheral tolerance in B cells

Answer 35

anergy: B cells usually require TH activation

lack of this –> anergy or apoptosis

Question 36

Ignorance in B cells

Answer 36

B cells in lymph nodes will not see self ag

Will not meet appropriate Th cell with the same self ag binding