Humoral Immunity B Cells Flashcards
Are B cells APCs?
yes! they can ingest protein antigens degrade them into peptides and display with MHC II for cd4 cells
stimulators of IgM synthesis
polysaccharides and lipids stimulate the production of IgM
Where is IgM found on B cells?
on the surface, it is the antibody that resided on surface to attach lipids and polysaccharide
stimulators of IgG IgA and IgE antibodies
peptide antigens noticed by CD4 cells lead to induction of production of these
B cell maturation cell lineage
stem cell Pro-B Pre-B Immature B Mature B
Ig expression in Pre-B lymphocyte cells
is in the cytoplasm
Ig expression in immature B lymphocyte cells
membrane now has IgM
Ig expression in mature B lymphocyte cells
have IgM and IgD on membrane
Where does clonal expansion of B cells occur?
in the lymph nodes or spleen!
Fc and Fab regions of antibodies
Fab regions are antigen binding
Fc regions are not antigen binding
What cells bind at Fc region of antibody?
macrophages, neutrophils NK cells, mast, basophils eosinophils
IgA locations and function
on body surfaces to protect from outside foreign pathogens
IgG locations and function
found in all body fluids
most common antibody
fight bacterial and viral infections
only antibody that can cross into placenta
IgM locations and function
found in the lymph and blood
first antibody made in response to an infection
pentamer, large,
IgE locations and function
found in lungs skin and mucous membranes
involved in allergic reactions
IgD location and function
found on the cell surface of newly synthesized B cells
just a cell surface receptor
Antibodies for neutralization?
IgG and IgA
Antibody for opsonization?
IgG
Antibodies for complement activation?
IgM is best and some IgG
Antibody for transport across epithelium?
IgA
Antibody for diffusion into extravascular sites?
IgG is best
Antibody with highest serum level?
IgG
3 types of mature B cells?
follicular B cells
marginal zone B cells
B-1 lymphocytes
follicular B cells location and function
in the follicles of spleen and in lymph nodes
can isotype switch, high affinity antibodies produced, long lived plasma cells
Marginal zone B cells location and function
in the marginal zone of splenic follicles
make IgM and have short loved plasma cells
B-1 cells location and function
peritoneal cavity and lymphoid organs and mucosal tissue
makes IgM and short lived plasma cells
antibody isotype in first compared to second exposure?
in first there will be a lot of IgM and then in second there will be more IgG
What is C3d and what is its role in B cell activation?
c3d is the breakdown product of c3b from complement
it will bind the Cr2/cd21 receptor on B cells and help activate them when an antigen is attached to its membrane antibody
Do B cells have TLRs? What is function?
yes they have them so they can recognize microbial products…it is a linkage between the innate and adaptive immunity
How do CD4 cell interacts with B cells
they bind the MHC class II peptides on the B cell
What is made by CD4 cells to help B cells proliferate?
cytokines and CD40
germinal center of a lymph node function
activated B and cd4 T cells come back to a follicle in the lymph node and cause proliferation of the B cells,..which is the germinal center
in the germinal center there is a lot of class switching anf somatic mutations for the antibodies
steps of B cell activation and proliferation in a lymph node….
- CD4 T cell is activated and B cell is activated and goes to the extrafollicular space
- The effector CD4 cell interacts with a B cell and stimulates it in an extrafollicular space
- B cell starts to make short lived plasma cells
- short lived plasma cells and the CD4 T cell go back into a follicle
- the plasma cells and T cells stimulate the follicle B cells to start proliferating and maturing
cytokine inducing switch to IgG antibodies? What T Cell?
Interferon gamma
Th1
cytokine inducing switch to IgE antibodies? What T cell?
IL-4
Th2
cytokine inducing switch to IgA antibodies? What T cell?
cytokines in mucosal tissues like TGF-beta and BAFF
Th17
