W7- Lecture 32- B cell & Antibodies Flashcards
(31 cards)
Describe the activation of t helper cells
Antigen presenting cell MCH2/antigen complex’s bind to specific T cell receptor allows activation
B7 on antigen presenting cell binds to CD28 on the T cell
Cell to cell interaction allow survival
Cytokines activate differentiations
Descibe the activation of cytotoxic T cells
MHC1/antigen complex bind to t helper cell
And b7 binds to cd28
Proliferation
T helper cell releases cytokines
Costimulation by CD4 cells that have come across the same antigens
Induces proliferation
What are the function of IgD antibodies
Antigen receptor virgin B-cells
IgM
Function
Agglutinin; activates complement
IgG
Function
Opsonin; activates complement
IgA
Function
Secretory; protects mucosa
IgE
Function
Inflammatory; protection vs helminths
Name the five types of antibodies
IgD IgM IgG IgA IgE
Where do you find B cells ?
Lymphatic tissues
Describe the activation of B cells
Activated by B cell receptors binding to specific antigens
B cells respond to antigens by taking in some of the antigen then combining with MCH2 receptions and
displaying this on the cell surface
Complex is recognised by helper T cells which secrete Cytokines (IL-2,4,6)
These co stimulate the B cells
Activation - enlarge and differentiate into plasma cells which secrete antibodies
Some differentiate into memory cells
What hold the heavy and light chains of the antibodies together ?
Disulphide bonds
How many epitopes can an antibody bind ?
How ?
2
Flexibility of the hinge region allows the two recognition sites to bind widely to separate antigens
How many amino acids do we expect in a heavy/ light chain of antibodies ?
450
220
Where is the hinge region on an antibody ?
Where the heavy chains are held together by disulphide bonds
What are the variable regions on an antibody ?
Where ?
Function
found at the tips of the H and l chains at the apex of the antibodies arms.
2 binding sites
What is the constant region of an antibody ?
Where ?
Differences with other antibodies ?
regions of the H and L chains not associated with antigen binding.
The C region of the H chain does vary slightly between different classes
Makes the difference between 5 types
Where can you find IgA
Function
Structure
Found in tears, breast milk , saliva, and mucus
Protects from pathogens
2x IgD antibodies bound together
Where can you find IgD
Function
On B cells
As receptor - activates basophils and mast cells
FUNCTION of IgE
Protects against parasitic worms
+ Responsible for allergic reactions
Where can you find IgM
Function
Structure
Attached to immature B cells + secreted in blood
Responsible for early stages of immunity
5x IgE antibodies bound by disulphide bridges
What are the 6 main functions of antibodies ?
Neutralisation Agglutination (immobilisation or attaching to flagella ) Precipitation Competitive fixation Opsonisation (triggers phago) Activation of nk cells
Describe how antibodies activate natural killer cells + action
Antibodies bind to target cells
Fc receptors on nk cell recognise antibodies + bind
Conformational change in the fc region of the antibody
This change signals degranulation and killing of target cells
Describe how antibodies activate mast cells + action
Multiple antibodies bind to mast cell
The cross links bound from adjacent IgE
cause granules to release contents including histamine and other inflammatory regulators
Which antibodies can neutralise pathogens ?
IgM
IgG 1,2,3,4
IgA
