immunoregulation

Question 1

what is the function of Tregs

Answer 1

prevent excessive immune responses to foreign antigens and immune responses to self-antigens missed by tolerization

Question 2

cell surface markers expressed by Tregs

Answer 2

CD4+
FoxP3+
CD25+

Question 3

autoimmune disease caused by inability to produce Treg cells

Answer 3

IPEX syndrome

Question 4

CTLA-4

Answer 4

expressed by Tregs
inhibit activation of T cells
binding of CTLA-4 to B7 molecules on APCs reduces ability of APCs to activate T cells

Question 5

IL-10

Answer 5

suppresses immunity by shutting down IL-12 production by dendritic cells and macrophages
downregulates expression of costimulatory molecules and class II MHC

Question 6

TGF beta

Answer 6

suppresses activation of macrophages and TH1 cells

promotes development of more Tregs

Question 7

how do Tregs suppress immune responses

Answer 7

production of suppressive cytokines IL-10 and TGF beta
binding of CTLA-4 to B7 molecules on APCs
consumption of IL-2, depriving other cells of this growth factor

Question 8

cytokines that downregulate immunity

Answer 8

IL-10 and TGF beta

Question 9

induced state of unresponsiveness to an antigen

Answer 9

tolerance

Question 10

characteristics of tolerance

Answer 10

antigen-specific
self-acquired/not inborn
all individuals have capacity to respond to self antigens, and therefore to develop autoimmunity

Question 11

antibody feedback

Answer 11

a

Question 12

idiotypic regulation

Answer 12

a

Question 13

central tolerance

Answer 13

occurs in bone marrow or thymus

Question 14

clonal deletion

Answer 14

deletion of self-reactive lymphocytes in bone marrow or thymus
AKA central tolerance

Question 15

clonal anergy

Answer 15

functional inactivation of lymphocytes in periphery

viability is maintained

Question 16

mechanisms of clonal anergy

Answer 16

functional inactivation of T cells in periphery

expression of self-antigens in absence of co-stimulatory molecules normally produces clonal anergy

Question 17

receptor editing

Answer 17

rearrangement of antibody genes to try to produce a non-self-reactive antibody
if still self-reactive after editing, undergoes clonal deletion

Question 18

thymocytes, on arrival to the cortex of the thymus, express

Answer 18

neither CD4 nor CD8

double negative

Question 19

as thymocytes course through the cortex, they express

Answer 19

CD4 AND CD8

become double positive

Question 20

what destroys thymocytes

Answer 20

corticosteroids

Question 21

duration of T and B lymphocyte tolerance

Answer 21

T = long lasting
B = short lived

Question 22

positive thymic selection

Answer 22

eliminates thymocytes that recognize foreign MHC proteins
leaves behind self-reactive T lymphocytes
mediated by thymic cortical epithelial cells (thymic nurse cells)

Question 23

negative thymic selection

Answer 23

eliminates self-reactive T lymphocytes

carried out by DCs at cortico-medullary junction

Question 24

AIRE gene

Answer 24

allows thymus to express tissue specific self antigens that can be used in the negative selection process