lecture 36 Flashcards
what are the 5 classes of antibodies we need to know about
IgM, IgG, IgE, IgA and IgD
what form is IgG in
monomeric
please order the antibody classes in order of prevalence
IgG, IgA, IgM, IgE, IgD
whats IgGs prevalence
most common antibody in the blood.
whats the function of IgG
opsonisation and neutralisation. targets virus and bacteria
what does passive immunity mean
Passing the antibodies onto the fetus is called passive immunity as the fetus doesn’t develop its own immune cells, it is instead passed on from the mother to their developing child.
IgG is the only antibody to do
This is the only antibody that may cross the placenta as the fetus develops.
how long does passive IgG stay in the body
It can stay presnt in the bloodstream for a long time after being given to us by mothers in placenta. The IgG from mother will stay in blood until the baby can develop its own immune system.
what form is IgA present in in the blood and tissue
monomeric in the blood and dimeric in the mucosal tissue
what are the monomers of IgA and IgM linked by
a J chain
what are examples of mucosal tissue dimeric IgA is present in
Present in secretions such as tears, saliva, mucus, and breast milk
function of IgA
Its most important function is the protection of our mucosal membranes.
This is also an example of passive immunity as the antibodies are passed onto the breastfeeding child through the breastfeeding of their mother.
targets bacteria and virus
what antibodies do passive immunity
IgG and IgA
what form is IgM present in
pentameric form
whats cells are IgM presented on mainly
naive B cells
what’s the first antibody produced after initial exposure to an antigen
IgM
what is IgM good at
This is a good activator of the complement alternative pathway.
These are secreted at the start of the immune response so they are good activators of complement and thus good communicators between the stages of the innate and adaptive immune response.
when on the cell surface IgM is in what form, when secreted they go to what form
IgM on their cell surface as monomer. When secreted it forms to be pentameric. In pentameric form its best antibody for activating complement, so early immune response.
what form is IgE present in
monomer
distribution of IgE
Present in blood
at low concentrations
function of the IgE
These help to activate the mast cells
IgE evolved to protect us from multicellular parasites like worms
These are responsible for allergies. These activate mast cells which trigger parasite immunity. As the mast cells release the histamine. This histamine is whats also a part of an immune response.
what form is IgD in
monomer
what is IgD distribution
expressed on naive B cells
function of IgD
Suspect that it works in coordination with IgM as an antigen receptor. but we dont know exactly.
what type of cell is a B cell and where do they develop
lymphocytes being made in the bone marrow
whats a plasma B cell and a memory B cell
Plasma cells are activated B cells that secrete
antibody, Express antibody as BCR, but do not
secrete antibody. instead responding rapidly on second antigen exposure
what is native antigen and what does this mean for the antibodies
an antigen that is not yet processed by an APC to smaller parts. so B cell receptors can respond to any part of this whole unprocessed antigen.
where do the B cells mature and be made
they are made and matured in the bone marrow, making sure they arent self reactive
antibody is what as it has 2?
Antibody chain is bivalent as it has 2
Arms.
describe structure of the antibody
There are two identical light chains and two identical heavy chains.
clonal selection of the B cell occurs where
in the lymph nodes
what links the antibody to the plasma membrane
transmembrane domains
whats a naive b cell
A naive B cell is a B cell that has not been exposed to an antigen
what changes in class switching and why
the constant region of the antibody changes as the variable BCR is kept the same so that the antigen responds to the same antigen but it functions different
the B cell receptors on the B cell are
all identical in the antigen they detect
what are the three main functions of an antibody
1:neutralisation
2:opsonisation
3: complement activation
whats neutralisation and whats an example
For example, a toxin or virus that would bind to our cells can be blocked “neutralised” by antibodies.
Neutralisation can also come in the example of antigen binding to the covid-19 coat protein and preventing it from binding to our cells.
whats the constant region of the antibody
this is the part which is bound to the membrane and it does not come into contact with the antigen.
whats the order of prevalence for antibodies
GAMED
how are plasma B cells and memory b cells different
An activated B cell secretes antibodies and divides into plasma and memory cells.
These are different to the plasma cells as they don’t secrete antibody, but they do still present BCR on the plasma membrane. So when these memory B-cells encounter antigen they will become plasma cells, which then do secrete antibodies which then aids in the immune response.
how does a vaccine work
Vaccinating creates memory b cells in the body for next time it sees the pathogen.
These memory B-cells can stay in the lymphatic tissue and blood for years. so next time the antigen is present the immune response is fast
what antibody classes are secreted in primary and secondary immune responses
secondary: which in this time is mainly IgG. With some class switch to IgA and IgE
primary: In this time there is a relatively low amount of antibody produced and it is mainly IgM.
what are stimulation requirements for the B cells
cytokine secretion from CD4 and direct by the native antigen on the BCR
heavy chain is linked to light chain by?
disulfide bridges
