B3 T and B cell function

Question 1

adaptive immune responses are initiated by

Answer 1

adaptive immune responses are initiated by antigen and antigen-presenting cells in secondary lymphoid tissues

Question 2

dendritic cells in secondary lymphoid tissues

Answer 2

-immature dendritic cell reside in peripheral tissue
-dendritic cells migrate via lymphatic vessels to regional lymph nodes
-mature dendritic cells activate naive t cells in lymphoid organs such as lymph nodes

Question 3

how are CD4 and CD8 effective in responding to antigens

Answer 3

they have cell surface proteins which make direct contact to MHC mols

Question 4

proliferation T cell function

Answer 4

-huge diversity meaning antigen specific t cells are rare
-activated t cells are useful so need to proliferate to generate effective immune response

Question 5

T cell effector functions

Answer 5

CD4 T cells helper
CD8 T cells killer

Question 6

Polarisation of CD4 T cell response

Answer 6

Th1- secretes IFNy and activates macrophage functions
Th2- secretes IL-4 and helps antibody function

Question 7

Memory T cell function

Answer 7

-key feature of adaptive immune system
-vaccines
-distinct from innate immune system

Question 8

the 4 T cell functions

Answer 8

-proliferation
-effect functions
-polarisation of CD4 T cell response
-memory

Question 9

how does CD8 carry out effector function

Answer 9

-stimulation of naive t cell
(recogniton)
-proliferating t cell
(proliferation/differentiation)
-active effect t cells kill virus infected target cells
(effector function)

Question 10

how does CD4 carry out effector function

Answer 10

CD4 cells carry out their effector function by helping b cells make antibodies
-antigen recognition induces expression of effector molecules by the T cell, which activates the B cell
-B cell proliferation
-differentiation to resting memory cells and antibody secreting plasma cells

Question 11

what 3 kinds of signals do antigen-presenting cells deliver to naive t cells

Answer 11

1. activation
2. survival
3. differentiation

Question 12

stages of B cell activation

Answer 12

1. recognition of antigen by BCR leads to activation of B cell and internalisation of antigen
2. once internalised antigen is broken down into peptides
3. peptides are loaded into MHC II within B cell and presented to antigen specific CD4 T cells
4. If T cell also recognises antigen provides help to B cell (cytokines, costim)
5. allows B cell to fully activate and secrete antibodies

Question 13

what are B cells highly efficient at

Answer 13

presenting antigens that bind to their surface immunoglobin

Question 14

how do B cells provide help

Answer 14

CD4 helper t cells provide help to b cells via CD40
T cells influence antibody production through secretion of cytokine
induces proliferation of B cell and differentiation
-plasma cell (antibody secreting
-memory cell

Question 15

what do Tfh cells provide

Answer 15

viral specific Tfh cell provides help to B cells that recognise a linked epitope

Question 16

antibody summary

Answer 16

known as immunoglobulin (Ig0
multi unit protein
-heavy chain
-light chain
-disulphide bonds to link
2 regions
-variable region
-constant region

Question 17

antibody summary

Answer 17

known as immunoglobulin (Ig0
multi unit protein
-heavy chain
-light chain
-disulphide bonds to link
2 regions
-variable region
-constant region

Question 18

what is the binding site of an antibody

Answer 18

epitope
(can be linear sequence or based based on antigen folding

Question 19

what does the hinge region of Ig mols do

Answer 19

allows flexibility in binding to multiple antigens (60 or 90 deg)

Question 20

what can high affinity IgG and IgA do

Answer 20

neutralise toxins and block infectivity of viruses and bacteria

Question 21

what pathway do antibody:antigen complexes activate by binding to what

Answer 21

classical pathway
binding to C1q

Question 22

what receptors on phagocytes are activated by antibodies

Answer 22

Fc receptors

Question 23

what do Fc recep on phagocytes that are activated by antibodies bound to the surface on pathogens do

Answer 23

enable the phagocytes to ingest and destroy pathogens

Question 24

stages of phagocytosis and IgG

Answer 24

1. bacterium coated with complement and IgG antibody
2. when C3b binds to CR1 and antibody binds to Fc recep, bacteria are phagocytosed
3. macrophage membranes fuse, creating phagosome
4. lysosome fuse with vesicles, delivering enzymes that degrade the bacterium

Question 25

antibody isotypes

Answer 25

isotype of an antibody related to constant region expressed by B cell
different isotypes of antibody mediate different functions and associated with different locations

Question 26

what is associated with cytokines produced by CD4 helper T cells

Answer 26

isotype of antibody secreted by B cell (plasma cell)

Question 27

what cell expresses FceR1 which only binds with what Ig and the result of this

Answer 27

mast cells
when IgE binds to antigen it cross links FcR1 receptors and this results in degranulatin of mast cells
= anaphylaxis

Question 28

what cell expresses FcyR which only binds with what Ig and the result of this

Answer 28

macrophages
when IgG binds to ntigen on pathogen, FcyR receptors cross link and activates macrophage to engulf and destroy pathogen

Question 29

function and location of IgG

Answer 29

found in blood and extracellular fluid
neutralise toxins, viruses, and bacteria, opsonise them for phagocytosis and activate the complement system

Question 30

function and location of IgM

Answer 30

found in blood and lymph
present on B cells and function is to control B cell activation

Question 31

function and location of IgA

Answer 31

most abundant, mucous membranes (gut)
protects mucosal tissues from microbial invasion and maintain immune homeostatsis

Question 32

function and location of IgD

Answer 32

functions as a B cell antigen receptor
found on B lymphocytes
does not bind complement

Question 33

function and location of IgE

Answer 33

role in pathogenesis of allergies
found in lymphnodes draining site of antigen entry