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preactivation 587 pre-B cell receptor
Carl Prausnitz–Giles.
Prausnitz-Küstner reaction to ragweed antigen E in rhesus monkey. Skin
sensitized 2 days earlier with human serum from a ragweed-sensitive atopic
patient.
intradermal injection. This is followed by injection of the
antigen or allergen in question into the same site as the serum
injection. Fixation of the IgE antibodies in the “allergic”
serum to mast cells in the recipient results in local release of
the pharmacological mediators of immediate hypersensitivity
that include histamine. It results in a local anaphylactic reaction
with a wheal-and-flare response. This test is no longer
used because of the risk of transmitting hepatitis or AIDS.
preactivation
A provirus that continues untranscribed in the genome of a
host cell because of a lack of host cell stimulation.
pre-B cells
A stage of B cell development characterized by rearrangement
of heavy chain genes but not light chain genes.
Pre-B cells develop from lymphoid stem cells in the bone
marrow. These are large, immature lymphoid cells that
Bone marrow
stromal cell
(fibroblast)
FL
SDF-1
Primitive B
cell progenitor
Pre-B
Cytoplasmic
IgM
B220 +
CD43 –
CD24 +
FLT3 +
Mature B cell
IL-7
IgM –
B220 +
CD43 +
CD24 +
FLT3 +
+ IgD+
IgM
FL
IL-7
IL-11
SDF-1
Pre- or early
Pro-B cell
IgM –
B220 + CD43 +
CD24 + FLT3 –
Immature B cell
IgM +
FLT-3 bone marrow B cell lymphopoiesis.
Virgin B Mature B
Cytoplasmic Ig
surface IgM
Cytoplasmic Ig
surface IgM
Pre-B cell development.
IgD –
IgM –
B220 + CD43 –
CD24 +
Pre-B cell
Late Pro-B cell
Activated
B
Cytoplasmic
Ig surface IgM
express cytoplasmic μ chains but no light chains or surface
immunoglobulin and are found in fetal liver and adult bone
marrow. They are the earliest cells of the B cell lineage.
Antigen is not required for early differentiation of the B cell
series. Pre-B cells differentiate into immature B cells, followed
by mature B cells that express surface immunoglobulin.
Pre-B cell immunoglobulin genes contain heavy chain
V, D, and J gene segments that are contiguous. No rearrangement
of light chain gene segments has yet occurred. In
addition to their cytoplasmic IgM, pre-B cells are positive
for CD10, CD19, and HLA-DR markers. Pre-B cells have
rearranged heavy but not light chain genes. They express
cytoplasmic Ig μ heavy chains and surrogate light chains
but not Ig light chains. The pre-B cell receptor consists of μ
chains and surrogate light chains. These receptors transmit
signals that induce further pre-B cell maturation into
immature B cells.
pre-B cell receptor
A maturing B cell lymphocyte receptor comprised of a μ
heavy chain, an invariant surrogate light chain, and the
Igα/Igβ heterodimer. It is expressed at the pre-B cell stage,
and its appearance marks the end of heavy chain gene
rearrangement. The two proteins comprising the surrogate
light chain include the λ 5 protein, which is homologous to
the λ light chain C domain, and the Vpre-B protein, which
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