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polynucleotides 584 positive cross match
levels of muscle enzymes, and (4) electromyographic
findings of myopathy. Corticosteroids have been used
to decrease muscle inflammation and increase strength.
Methotrexate or other cytotoxic agents may be used when
steroids prove ineffective.
polynucleotides
A linear polymer comprised of more than 10 nucleotides
joined by 3′,5′-phosphodiester bonds; double-stranded DNA
chains that may serve as adjuvants when inoculated with
antigens.
polyomavirus immunity
Polyomavirus infections are usually associated with virus
reactivation in immunocompromised hosts. Two polyomaviruses,
JC virus (JCV) and BK virus (BKV), infect humans.
BKV and JCV infect children. In the United States, one half of
all children acquire antibodies to BKV during the first 3 years
of life and to JCV by the 10th to 12th year of age. Antibody
responsiveness is assayed by neutralization, hemagglutination
inhibition, and ELISA (enzyme-linked immunosorbent
assay). Antibody titers often increase during virus activation.
IgM antibodies that are virus-specific have been found in renal
allotransplant patients. Cell-mediated immunity develops
against BKV. JCV and BKV remain in the body after primary
infection. Cell-mediated immunity is believed to prevent or
limit virus reactivation in healthy individuals, but the viruses
are reactivated in immunosuppressed subjects.
polyreactive antibody
An immunoglobulin molecule that identifies and unites
with several different antigens of significantly different configurations
with varying affinities.
polyspecific anti-human globulin (AHG)
This is known as the Coombs’ reagent consisting of antibodies
against human IgG and C3d. It may also contain
anti-C3b, anti-C4b, and anti-C4d antibodies. Although it
demonstrates only minimal reactivity with IgM and IgA
heavy chains, it may interact with these molecules by reacting
with their κ or λ light chains. It is used for the direct
antiglobulin test.
polyspecificity
The capacity to bind many different antigens. Also
termed polyreactivity.
polyvalent
Multivalent.
polyvalent antiserum
An antiserum composed of antibodies specific for multiple
antigens.
polyvalent pneumococcal vaccine
An immunizing preparation that contains 23 of the 83
known pneumococcal capsular polysaccharides. It induces
immunity for 3 to 5 years and is believed to protect against
90% of the pneumococcal types that induce serious illness
in patients over 2 years of age. Children at high risk can be
vaccinated at 6 months of age and reinoculated at 2 years
of age. The vaccine is especially indicated in high-risk
patients such as those with sickle cell disease, chronic
debilitating disease, immunological defects, and the elderly.
Vaccination against pneumococcal disease is of increasing
significance as Streptococcus pneumoniae becomes
increasingly resistant to antibiotics.
polyvalent vaccine
A vaccine composed of multiple antigens from more than
one strain of a pathogenic microorganism or from a mixture
of immunogens such as the diphtheria, pertussis, and tetanus
toxoid preparation.
popcorn cells
Neoplastic cells in non-Hodgkin lymphoma manifesting
a surface phenotype of CD3 - CD15 - CD19 + CD20 ± . Their
immunoglobulin genes manifest somatic hypermutation.
Porcine immunity.
porcine immunity
The pig’s immune system differs from those of mice
and humans in that pigs have inverted lymph nodes; pig
lymphocytes leave lymph nodes in the blood rather than in
efferent lymph; pigs have four types of Peyer’s patches and
small tonsillar papillae in the tongue together with palatine
and nasopharyngeal tonsils; and pigs fail to transfer immunoglobulins
across the placenta. The pig major histocompatibility
complex (MHC) encodes the production of both
class I and class II products. Pigs have peripheral blood
leukocytes of the same type as found in humans. Unique
features of porcine blood leukocytes include a relatively
high proportion of γδ T cells, a high CD4 + /CD8 + ratio in
adults, and increased frequencies of CD4 + /CD8 + doublepositive
T cells. Four CD markers have been described,
and four classes of immunoglobulins (IgM, IgA, IgG, and
IgE) have been identified. Pigs have both αβ T cells and
γδ T cells, natural killer (NK) cells, adhesion molecules
of the E-selectin type, and cytokines that include interferons,
inflammatory cytokines, and chemokines. Other
pig cytokines include interleukin-2 (IL2), IL4, IL5, IL10,
IL12, granulocyte–macrophage colony-stimulating factor
(GM-CSF), and G-CSF, among others.
Porter, Rodney Robert (1917–1985)
British biochemist who with Gerald Edelman received the
Nobel Prize in 1972 for their studies of antibodies and their
chemical structures. Porter cleaved antibody molecules
with the papain enzyme to yield Fab and Fc fragments. He
suggested that antibodies have four-chain structures. Fab
fragments were shown to have the antigen-binding sites and
the Fc fragments conferred the biological properties of the
antibody. He also investigated the sequence of complement
genes in the major histocompatibility complex (MHC).
(Refer to Defense and Recognition, 1973.)
Portier, Paul Jules (1866–1962)
French physiologist who, with Richet, was the first to
describe anaphylaxis.
positive cross match
The demonstration via serological or flow cytometric
techniques of preformed antibodies specific for one or more