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crossed immunoelectrophoresis 202 Cryptococcosis neoformans immunity
crossed immunoelectrophoresis
A gel diffusion method employing two-dimensional
immunoelectrophoresis. Protein antigens are separated by
gel electrophoresis, followed by the insertion of a segment
of the gel into a separate gel into which specific antibodies
have been incorporated. The gel is then electrophoresed at
right angles to the first electroporesis, forcing the antigen
into the gel containing antibody. This results in the formation
of precipitin arcs in the shape of a rocket that resemble
bands formed in the Laurell rocket technique.
Crotalidae polyvalent immune Fab (ovine) (injection)
Fab fragment of immunoglobulin G (IgG) specific for
venom that acts by binding and neutralizing venom toxins,
facilitating their redistribution away from target tissues and
their elimination from the body.
Crow–Fucase syndrome
Refer to POEMS syndrome.
CRP
Abbreviation for C-reactive protein.
cryofibrinogenemia
Cryofibrinogen in the blood that is either primary or
secondary to lymphoproliferative and autoimmune
disorders, tumors, and acute or chronic inflammation.
Cryofibrinogenemia is often associated with immunoglobulin
A (IgA) nephropathy.
cryoglobulin
A serum protein (immunoglobulin) that precipitates or gels
when the temperature falls below 37°C. Cryoglobulins
undergo reversible precipitation at cold temperatures. Most
of them are complexes of immunoglobulin molecules, but
nonimmunologic cryoprecipitate proteins such as cryofibrinogen
or C-reactive protein–albumin complexes may
also occur. When the concentration of cryoglobulins is
relatively low, precipitation occurs near 4°C, but if the concentration
is greater precipitation occurs at a higher temperature.
Cryoglobulins are usually associated with infectious,
inflammatory, and neoplastic processes. They are found
in different body fluids and also appear in the urine. They
are divisible into three groups: Type I cryoglobulins are
monoclonal immunoglobulins, usually immunoglobulin
M (IgM), associated with malignant B cell neoplasms;
type II cryoglobulins consist of mixed cryoglobulins with
a monoclonal constituent specific for polyclonal IgG; and
type III cryoglobulins are mixed cryoglobulins composed
of polyclonal immunoglobulins as immunoglobulin–antiimmunoglobulin
complexes. Cryoglobulin is not present in
normal serum. Refer to cryoglobulinemia.
cryoglobulinemia
Cryoglobulins in the blood that are usually monoclonal
immunoglobulins (IgG or IgM). Polymeric IgG 3 may be
associated with cryoglobulinemia, in which the protein
precipitates in those parts of the body exposed to cooling.
Cryoglobulinemia patients develop embarrassed
circulation following precipitation of the protein in
peripheral blood vessels. This may lead to ulcers on the
skin and to gangrene. More commonly, patients manifest
Raynaud’s phenomenon following exposure of the hands
or other parts of the anatomy to cold. Cryoglobulins
may be detected in patients with Waldenström’s macroglobulinemia,
multiple myeloma, or systemic lupus
erythematosus (SLE). Cryoglobulinemias are divisible
into three types: type I monoclonal cryoglobulinemia,
often associated with a malignant condition (i.e., IgG
multiple myeloma, IgM macroglobulinemia, lymphoma
or chronic lymphocytic leukemia, and benign monoclonal
gammopathy); type II polymonoclonal cryoglobulinemia
with mixed immunoglobulin complexes such as
IgM–IgG, IgG–IgG, and IgA–IgG that may be linked to
connective tissue disease such as rheumatoid arthritis or
Sjögren’s syndrome or with lymphoreticular disease; and
type III mixed polyclonal–polyclonal cryoglobulinemia
with IgG and IgM mixtures, rarely including IgA, which
is associated with infections, lupus erythematosus,
rheumatoid arthritis, Epstein–Barr and cytomegalovirus
inclusion virus, Sjögren’s syndrome, crescentic and
membranoproliferative glomerulonephritis, subacute
bacterial infections, biliary cirrhosis, diabetes mellitus,
and chronic active hepatitis.
cryopreservation
The technique of freezing tissue or cells or other biological
materials so that they remain genetically stable and
metabolically inert. Cryopreservation may involve freezing
(–80°C) or preservation with dry ice (–79°C) or liquid
nitrogen (–196°C).
Cryostat ®
A microtome in a refrigerated cabinet used by pathologists
to prepare frozen tissue sections for surgical pathologic
diagnosis. Immunologists use this method of quick
frozen thin sections for immunofluorescence staining
by fluorochrome-labeled antibody to identify antigens,
antibodies, or immune complexes in tissue sections such
as renal biopsies.
cryptantigens
Surface antigens of red cells not normally detectable but
demonstrable by microbial enzyme action that leads to the
modification of cell surface carbohydrates. Naturally occurring
immunoglobulin M (IgM) antibodies in normal serum
may agglutinate these exposed antigens.
cryptic epitope
An antigenic determinant concealed from the immune system
in health but exposed during inflammation or infection.
Cryptococcosis neoformans immunity
The polysaccharide capsule of C. neoformans serves as an
antiphagocytic mechanism. It blocks binding sites recognized
by phagocytic receptors for β-glucan and mannan
that may mediate phagocytosis and secretion of TNFα.
The capsule also covers immunoglobulin G (IgG) bound
to the cell wall, but it is the site of complement activation
in the alternative pathway in which IC3b fragments may
facilitate opsonization. Neutrophils, monocytes, and natural
killer (NK) cells all show anticryptococcal activity in vitro.
Nonencapsulated C. neoformans generates elevated levels
of interleukin-2 (IL2) and interferon-γ (IFN-γ) in vivo.
The polysaccharide capsule may also induce suppressor
T cells that synthesize a factor that inhibits binding of the
organism by macrophages. Critical to immunity to this
fungus is the recognition of encapsulated C. neoformans by
antigen-specific mechanisms. A specific immune response
is essential to control encapsulated C. neoformans. NK and
T cells exert their antifungal action against C. neoformans
independent of oxygen or nitrogen radicals. T cell-mediated
immunity is critical for acquired immunity against C.
neoformans. NK cells have also been shown to play an
important role.