Adaptive Immunity 2 Flashcards
Where do B cells mature?
bone marrow
Where do B cells circulate and where are they found in large amounts
circulate in blood and lymph
found in lymphoid organs
How do B cells identify antigens?
B cell receptor (BCR)
What are BCRs usually?
antibodies
IgM and IgD
What quality in BCR allows identification of multiple antigens?
diversity
What are the 5 classes of immunoglobulins/antibodies?
IgG, IgE, IgD, IgM and IgA
What is the most prominent antibody in the body, where is it found and what is its role?
IgG
blood and bodily fluids
responsible for resistance against viruses, bacteria and bacterial toxins
IgG triggers phagocytosis to initiate opsonization reaction (complement cascade)
What is the role of IgE?
attaches to mast cells and basophils causing them to release histamine
What is the role of IgD?
on the surface of B cells where it binds to antigens
What is the role of IgM?
capable of binding multiple antigens
first class of antibody secreted after antigen is encountered
primary barrier against pathogens
declines as IgG accelerates
What is the role of IgA and where is it found?
attack pathogens before they enter internal tissues
found in secretions of saliva, sweat, mucus, urinary tract, semen, digestive tract
What differs in B cell receptor structure to T cells?
B cell receptors do not have alpha and beta chains
instead light and heavy chains
What is each developmental B cell stage defined by?
rearrangement of light and heavy chains
What genes does heavy chain rearrange?
Variable
Diversity
Joining
What genes does light chain rearrange?
Variable
Joining
What is the usual receptor for immature B cells?
IgM
What are the receptors for mature B cells?
IgM
IgD
What do B cells undergo before release?
negative selection in bone marrow
What will happen to B cells which do not pass negative selection?
engulfed by macrophages
What are the 3 main functions of antibodies?
Neutralisation
Opsonization
Initiation of complement
What is neutralisation?
attach to toxins or viruses and then inactivate them
What is opsonisation?
coating of pathogens by antibodies or complement proteins
What are the processes that opsonisation can trigger?
Phagocytosis
Antibody dependent cellular cytotoxicity (ADCC)
Mast cell degranulation