B lymphocytes Flashcards
Give characteristics of adaptive immunity
increase efficacy of innate
focused response
memory
takes time
What does humoral mean?
B cells and antibodies
Whats is the B cell receptor?
surface bound antibody that encodes the antibody the cell will make
What is the BCR linked to and why?
IgA and IgB as cytoplasmic tails of these are long enough to interact with intracellular signalling molecules
How does antigen receptor diversity happen?
gene recombination
Summarise the process of gene rearrangement
progenitor B cell undergoes maturation gene rearrangement happens
each BCR chain (heavy or light) is encoded by separate multigenerational families on different chromosomes
What enzyme joins the segments together?
VD(J) recombinase
How many regions do light and heavy chains have to recombine and what are they?
light = V+J heavy = V+J+D
How many types of light chain are there and what are they called?
kappa
lambda
Summarise B cell development
selected for self tolerance
gene rearrangement
maturation
What do B cells require to be activated alongside the antigen?
accessory signal from Th Cell or microbial constituents
How do thymus independent antigens work?
directly activate B cell without Th cell help
polysaccharide needs to be repetitive and accessory signal provided by microbial constituents or accessory cell
Give 2 characteristics of thymus independent antigens
only IgM
no memory
How do thymus dependent antigens work?
requires a Th cell
dendritic cell takes up antigen and presented on surface with MHC class 2 molecule
Th cell recognises complex and is activated
B cell has antigen bound to BCR then internalises and degrades into peptides and presents on MHC class 2
complex recognised by activated CD4 Th Cell and B cell activated
Give 2 characteristics of thymus dependent antigens
all Ig
memory
