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paradoxical reaction 554 paraproteinemias
paradoxical reaction
Deaths of experimental animals from anaphylaxis when
administered a second injection of an antigen to which they
had been previously immunized. Early workers administering
repeated injections of tetanus toxoid observed the
phenomenon. This term is no longer in use.
paraendocrine syndromes
Clinical signs and symptoms induced by hormones synthesized
by neoplasms.
paraimmunoglobulins
(l) The physical characteristics of some immunoglobulins
present in a variety of pathologic conditions and in
others of unknown etiology. (2) The secretory products of
neoplastic lymphocytes. One form, the M protein of macroglobulin,
is present in the normal serum, but increased
levels may result in increased serum viscosity with sluggish
blood flow and development of thrombi or central
nervous system lesions. Increased levels of M protein are
considered paraimmunoglobulinopathies.
parainfluenza virus (PIV) immunity
Immunity against parainfluenza virus infection (manifested
clinically as croup, upper respiratory infections, and
pharyngitis) is exhibited as an increase in immunoglobulin
G (IgG) antibodies to PIV in 93, 81, and 80% of PIV type
1, 2, and 3 infections, respectively. IgM antibodies occur
in 40 to 90% of cases. There are common cross reactions
of IgG antibodies to PIV 1 and 3 but not of antibodies to
PIV 2 and PIV 1 and 3. Cross reactions are less frequent
with IgM antibodies. Enzyme immunoassay (EIA) is more
sensitive than complement fixation but is of lower specificity
because of cross reactions of PIV with mumps virus.
Type-specific PIV antigens are found in 94 to 100% of
culture-positive nasopharyngeal aspirates.
paralysis
The masking of an immune response by the presence
of excessive quantities of antigen. This finding mimics
acquired immunologic tolerance and is considered a false
tolerance state.
paralyzed TCRs
T cell receptors that have united with but cannot release an
antagonist ligand. Also called spoiled TCRs.
paramyxovirus immunity
Both serum antibody and cell-mediated immunity are
induced by infection with human paramyxoviruses that
cause such common childhood diseases as measles,
mumps, and respiratory tract infections. Both limbs of
the immune response are important for recovery from
disease, although their relative significance varies with
the virus of this group. Secretory antibody is important
in some of them, such as respiratory infections, but it
is only partially protective. Almost all of the virusencoded
proteins induce serum antibody detectable
after infection. Antibodies specific for M protein and
F protein are usually of low titer. Even though antinucleocapsid
antibody is often present in high titer, the
only neutralizing antibodies are those specific for the
attachment protein and the fusion protein and are thus
protective. Antibodies against either F or HN proteins
are protective, but the greatest protection is induced
when both antigens are used for immunization. The
cell-mediated immune response to paramyxoviruses
remains to be defined. These viruses may evade the host
immune response and nonspecifically suppress cellmediated
immunity through infection of monocytes and
macrophages as observed in measles infection. They
also evade host immunity by establishing a persistent
infection. Measles, mumps, Newcastle disease, canine
distemper, and rhinderpest virus vaccines are presently
available. These are all live attenuated virus vaccines.
paraneoplastic autoantibodies
Autoantibodies that cross react with tumor and normal tissue
in the same patient. Examples are Yo antibodies against
cerebellar Purkinje cells that occur in paraneoplastic
cerebellar degeneration, neuronal nuclear (Hu) antibodies in
paraneoplastic subacute sensory neuronapathy and sensory
neuropathies, antikeratinocyte polypeptides in paraneoplastic
pemphigus, antibodies against voltage-gated calcium
channels in Lambert–Eaton syndrome, antibodies against
retina in retinopathy associated with cancer, and antibodies
against myenteric and submucosal plexuses in pseudoobstruction
of the intestine.
paraneoplastic autoimmune syndromes
Paraneoplastic syndromes affect specific organ systems and
are induced by tumors but are caused by remote effects of
neoplasms and not by direct infiltration or tumor metastases.
Neoplasms may induce perturbations of the immune system
with injurious effects on various organ systems such as the
central nervous system, eyes, and skin. Tumor–immune
system interaction induces tissue injury in distant organs by
various mechanisms such as autoantibody-induced tissue
injury.
paraneoplastic pemphigus
A rare autoimmune condition that may occasionally be
seen in lymphoproliferative disorders. It is caused by
autoantibodies against desmoplakin I, bullous pemphigoid
antigen, and other epithelial antigens. Clinically, erosion
of the oropharynx and vermilion border is observed along
with pseudomembranous conjunctivitis and erythema of the
upper trunk skin.
paraneoplastic syndrome
Clinical symptoms attributable to the indirect action of a
malignant neoplasm on remote organs or tissues.
paraprotein
Homogeneous, monoclonal immunoglobulin molecules synthesized
by an expanding clone of plasma cells, as observed
in patients with plasma cell dyscrasias such as multiple
myeloma or Waldenström’s macroglobulinemia. The
homogeneity of the paraprotein is reflected by all molecules
belonging to the same immunoglobulin class and subclass
as well as the same light chain type. On electrophoresis,
a serum paraprotein appears as a distinct band. This is a
consequence of a biologic event such as neoplastic transformation
rather than antigenic stimulation.
paraproteinemias
Malignant diseases in which proliferation of a single clone
of plasma cells produces monoclonal immunoglobulin.
These are commonly grouped as paraproteinemias that may
be manifested in several forms. Diseases associated with
paraproteinemias include multiple myeloma, Waldenström’s
macroglobulinemia, cryoglobulinemia, plasmacytoma of
soft tissues, amyloidosis, heavy chain disease, lymphomas,
leukemias, sarcomas, gastrointestinal disorders associated
with tumors, chronic infections, and some endocrine
disorders.