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plasmacyte 576 plasma pool
Plasma cells.
Electron micrograph of plasma cell. N = nucleus. M = mitochondria.
G = Golgi apparatus. ER = endoplasmic reticulum.
size. Mature plasma cells have abundant cytoplasm, which
stains deep blue with Wright’s stain, and have an eccentrically
located round or oval nucleus, usually surrounded by
a well defined perinuclear clear zone. The nucleus contains
coarse and clumped masses of chromatin, often arranged in a
cartwheel fashion. The nuclei of normal, mature plasma cells
have no nucleoli, but those of neoplastic plasma cells such as
those seen in multiple myeloma have conspicuous nucleoli.
The cytoplasm of normal plasma cells has a conspicuous Golgi
complex and rough endoplasmic reticulum and frequently
contains vacuoles. The nuclear to cytoplasmic ratio is 1:2.
By electron microscopy, plasma cells show very abundant
endoplasmic reticulum, indicating extensive and active protein
synthesis. Plasma cells do not express surface immunoglobulin
or complement receptors which distinguishes them from B
lymphocytes. Plasma cells that are short-lived differentiate
quickly without manifesting isotype switching or somatic
hypermutation leading to the secretion of low affinity IgM
antibodies. Plasma cells that are long-lived differentiate following
isotype switching and somatic hypermutation, which leads
to the secretion of high-affinity antibodies that have various
effector functions.
plasmacyte
Plasma cell.
plasmacytoid dendritic cells (PDCs)
Cells with a dendritic-like appearance arising from interferon-synthesizing
cells activated in culture by inflammatory
cytokines and products of microbes.
plasmacytoma
A plasma cell neoplasm. Also termed myeloma or multiple
myeloma. To induce an experimental plasmacytoma
Bone marrow plasmacytoma with pure plasma cell infiltrate.
in laboratory mice or rats, paraffin oil is injected into the
peritoneum. Plasmacytomas may occur spontaneously.
These tumors, composed of neoplastic plasma cells, synthesize
and secrete monoclonal immunoglobulins, yielding a
homogeneous product that forms a spike in electrophoretic
analysis of the serum. Plasmacytomas were used extensively
to generate monoclonal immunoglobulins prior to
the development of B cell hybridoma technology to induce
monoclonal antibody synthesis at will to multiple antigens.
plasma half-life (T 1/2 )
Determination of the catabolic rate of any component of the
blood plasma. With respect to immunoglobulins, it is the
time required for one half of the plasma immunoglobulins
to be catabolized.
plasma histamine
Even though histamine released from basophils and mast
cells is a critical step in immediate hypersensitivity reactions,
plasma histamine levels are rarely determined due to
the short half-life of histamine in plasma. Thus, mast cell
tryptase and thromboxane A 2 are the preferred analytes due
to their longer half-lives.
plasmapheresis
A technique in which blood is withdrawn from an individual,
the desired constituent is separated by centrifugation,
and the cells are reinjected into the patient; for example,
plasma components may be removed from the circulation of
an individual by this method. The technique is also useful
to obtain large amounts of antibodies from the plasma of
an experimental animal. Plasmapheresis is used therapeutically
to rid the body of toxins or autoantibodies in the blood
circulation. Blood taken from the patient is centrifuged, the
cells are saved, and the plasma is removed. Cells are resuspended
in albumin, fresh normal plasma, or albumin in
saline and returned to the patient. The ill effects of a toxin
or of an autoantibody may be reduced by 65% by removing
approximately 2500 mL of plasma. Removal of twice
this amount of plasma may diminish the level of a toxin or
of an autoantibody by an additional 20%. This procedure
has been used to treat patients with myasthenia gravis,
Eaton–Lambert syndrome, Goodpasture’s syndrome, hyperviscosity
syndrome, post-transfusion purpura, and acute
Guillain–Barré syndrome.
plasma pool
The amount of plasma immunoglobulin per unit of body
weight. This may be designated as milligrams of immunoglobulin
per kilogram of body weight.