adaptive immunity: B cells

Question 1

what are B cells?

Answer 1

communicate with T cells, have specific B cell receptor for antigens, produce antibodies

Question 2

what is clonal expansion?

Answer 2

generation of 2 subsets

Question 3

what ae plasma cells

Answer 3

large antibody factories

Question 4

what are memory B cells?

Answer 4

mount a quicker antibody response to any subsequent infections

Question 5

where do you find B cells?

Answer 5

mature in bone marrow, circulate in blood and lymph and are found in large numbers in lymphoid organs

Question 6

how do B cells recognize antigens?

Answer 6

through B Cell Receptor which is actual antibody - diversity

Question 7

what do b cells become once activated

Answer 7

plasma cells

Question 8

what are the 5 types of immunoglobulins produces by b cells (as receptors)

Answer 8

IgG, IgE, IgD, IgM, IgA

Question 9

describe b cell receptor structure

Answer 9

different to t cells, but has variable and constant regions, and light and heavy chains

Question 10

what are the 3 main functions of antibodies?

Answer 10

neutralization, opsonization, initiation of complement

Question 11

what is the goal of antibodies?

Answer 11

prevent microbial activity and aid removal of threat from host

Question 12

what is opsonisation?

Answer 12

coating of pathogens by antibodies or complement proteins; phagocytosis, antibody dependent cellular cytotoxicity, mast cell degranulation

Question 13

describe b cell development

Answer 13

each development stage is defines by rearrangements of the immunoglobulin heavy and light chain genes, once in periphery b cells migrate to secondary lymphoid organs

Question 14

what are the components of heavy chain?

Answer 14

variable, diversity and joining genes

Question 15

what are the components of light chain?

Answer 15

variable and joining genes

Question 16

what immunoglobulins do immature and mature b cells express?

Answer 16

immature = IgM
mature = IgM and IgD

Question 17

how do b cells undergo negative selection?

Answer 17

macrophages engulf and remove self- reacting b cells

Question 18

what are the 2 types of b cell activation?

Answer 18

thymus-dependent
antigens which don’t require t cell help
thymus-independent
antigens which dont

Question 19

describe b cell activation

Answer 19

occurs n lymph nodes

activation of naïve b cell results in rise of plasma cells

Question 20

describe thymus-dependent activation

Answer 20

co-receptor binding, cytokine signals released from t helper cells induce proliferation
generates pool of plasma cells which produce antibody
also generates memory b cells
plasma cells initially produce IgM

Question 21

describe thymus-independent activation

Answer 21

certain antigens can activate directly, cells differentiate into plasma and produce IgM but antibody response weaker than antigen dependant b cell activation, doesn’t lead to generation of memory cells

Question 22

what is class switching?

Answer 22

caused by class switching, IgM response is weak, cells class switch to IgG, occurs by gene rearrangement, but antigen binding site remains same, antibody has increasing affinity for antigen

Question 23

what is avidity?

Answer 23

ability of antibodies to form complexes

Question 24

what is cross talk?

Answer 24

in lymphoid organs, between B and T cells, leads to generation of both humoral and cellular immune response

Question 25

what are germinal centres?

Answer 25

hubs for t and b cross talk, also proliferation, differentiation, somatic hypermutation-class switching

Question 26

describe the vaccination process

Answer 26

in primary immune response IgM acts early but as b cells undergo class switching an IgG response follows, presence of memory t and b cells means on 2nd exposure immune system responds much faster, cells also primed to produce more effective IgG response immediately

Question 27

what is immunological tolerance?

Answer 27

an active response to a particular antigen-central and peripheral

Question 28

what is central tolerance

Answer 28

in primary lymphoid organs- thymus for t and bone marrow for b, + and - selection eliminates >90% of t cells

Question 29

what is peripheral tolerance (t cells)

Answer 29

not all self reactive t cells are eliminated, however peripheral tolerance prevents their activation

Question 30

signal 1, no signal 2 =

Answer 30

anergy

Question 31

signal 1 + 2 no 3 =

Answer 31

deletion by apoptosis

Question 32

what can Treg cells do in peripheral tolerance?

Answer 32

directly block activity by binding antigen

Question 33

what is peripheral tolerance (in b cells)

Answer 33

occurs in secondary lymphoid organs, self reactive b cells still require help from self reactive t cells, since most eliminated the b cells become anergic

Question 34

what is breach of tolerance?

Answer 34

to self antigens or commensal organisms drived many autoimmune diseases