Untitled - D Ank Unlimited

CD21 144 CD23
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Structure of CD21.
CD21
CD21
A 145-kDa glycoprotein that is a component of the B cell
receptor. CD21 is a membrane molecule that participates in
transmitting growth-promoting signals to the interiors of B
cells. It is the receptor for the C3d fragment of the third component
of complement, CR2. The CD21 antigen is a restricted
B cell antigen expressed on mature B cells. It is present at high
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Structure of CD21.
density on follicular dendritic cells (FDCs), the accessory cells
of the B zones. Also called complement receptor 2 (CR2).
CD21 antigen
A restricted B cell antigen expressed on mature B cells.
The antigen is present at high denisty on follicular dendritic
cells (FDCs), the accessory cells of the B zones. It
shows moderate labeling of B cells and a strong labeling
of FDC in cryostat sections, whereas the staining of B
cells is reduced or abolished in paraffin sections. However,
the labeling of FDC in paraffin sections is as strong as on
cryostat sections.
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CD22
A molecule (molecular weight of α130 and β140 kDa)
expressed in the cytoplasm of B cells of the pro-B and
pre-B cell stages and on the cell surfaces of mature B cells
with surface immunoglobulin (Ig). The antigen is lost
shortly before the terminal plasma cell phase. The molecule
has five extracellular immunoglobulin domains and
shows homology with myelin adhesion glycoprotein and
with N-CAM (CD56). It participates in B cell adhesion to
monocytes and T cells. Also called BL-CAM.
CD23
An antigen (molecular weight of 45 to 50 kDa) that is an
integral membrane glycoprotein. The CD23 antigen has
been identified as the low affinity Fc-IgE receptor (FceRII).
Two species of FceRII/CD23 have been found. FceRIIa and
FceRIIb differ only in the N terminal cytoplasmic region
and share the same C terminal extracellular region. FceRIIa
is strongly expressed on IL4-activated B cells and weakly
on mature B cells. FceIIa is not found on circulating B cells
and bone marrow B cells positive for surface IgM, IgD.
FceRIIb is expressed weakly on monocytes, eosinophils,
and T cell lines. However, IL4-treated monocytes show a
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Structure of CD22.