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ASO
anti-streptolysin O
Latex particles coated with
streptolysin O are agglutinated when mixed with samples containing
ASO. In those infections promoted by acute streptococcal infection,
anti-streptolysin O antibodies are produced due to the presence of
the streptolysin O antigen liberated by the bacteria. Information on
the extent and degree of infection can be obtained from the
measurement of serum ASO levels however increased ASO levels are
also associated with rheumatic fever and glomerulonephritis.
CRP
Latex particles coated with goat
anti-human CRP antibodies are agglutinated when mixed with samples
containing CRP.
CRP is a serum constituent originally
defined by its ability to precipitate Pneumococcus C polysaccharide.
Characteristically, CRP appears in the serum of individuals in
response to various inflammatory conditions and tissue necrosis and
disappears as the causative conditions subside.
It is routinely found in cases of
bacterial infection, active rheumatic fever and many malignant
diseases and is often seen in association with cases of rheumatoid
arthritis, viral infections and tuberculosis. CRP has also been
detected in patients following blood transfusions and surgical
operations
as well as in patients with
burns, pemphigus vulgaris and other bullaous lesions.
RA
An abnormal protein occurs in the
serum of many patients suffering from rheumatoid arthritis. This
protein behaves as if it were an IgM antibody directed against
determinants of IgG globulins. Detection of the rheumatoid factor
protein is of value in the diagnosis of rheumatoid arthritis. Singer
and Plotz(1956:1958) described a method of detecting rheumatoid
factor using a suspension of fine plastic granules coated with human
gamma globulins which were agglutinated in the presence of
rheumatoid factor. The RA latex reagent is a sensitive, standardised
preparation of this type, made with a purified human IgG fraction
and selected polystyrene latex.
s-LE
In s-LE, autoantibodies directed
against native deoxyribonucleic acid and other nuclear constituents
are produced. It is classed as the prototype of severe autoimmune
diseases, involving a variety of tissues and associated with a wide
range of antibodies in the circulation. Characteristics of the
disease are antibodies against native DNA, nucleoprotein, denatured
DNA and other extractable nuclear antigens. S-LE also affects a wide
range of tissue. Organs affected are, in decreasing incidence,
joints, skin, kidney, central nervous system, heart and lungs. One
other important feature is the high frequency of the disease in
women, approximately 3 to 4 times more frequent than in men. The
high incidence of s-LE between monozygous twins (70-80%) and of
close relatives (5-10%) indicates that s-LE may be a hereditary
disease.
Toxoplasmosis
Toxoplasma is an infectious disease
affecting various mammalian species including man. Infection is
caused by the protazoan parasite Toxoplasma Gondii. Infection
is usually acquired by ingesting inadequately cooked meat or from
faeces of infected cats. The acquired disease is usually mild and
not diagnosed. In pregnant women patients can transmit the infection
across the placenta to the foetus causing congenital Toxoplasmosis.
Disease manifestations depend on the stage of foetal development;
although the foetus is less likely to be infected early in
pregnancy, the effects on those infected are more severe during the
first trimester of pregnancy. The consequences of congenital
toxoplasmosis range from spontaneous abortion and prematurity to
neurological congenital abnormalities. Some infants may be
asymptomatic at birth and develop disease during childhood or
adolescence (chorioretinitis).
Infectious Mononucleosis
Infectious mononucleosis involves the
reticuloendothelial tissue and is believed to be caused by the
Epstein Barr virus. It is generally limited to and affects children
and young adults. Infectious Mononucleosis may be confused on a
symptomatic basis with other diseases. For this reason, an accurate
diagnosis using this procedure is necessary. Detectable levels of
unique heterophile antibodies are produced in patients with
infectious mononucleosis2.
The antibody of the IM was shown by Paul and Bunnell
2
to agglutinate sheep and horse
erythrocytes and Bunnell 3
subsequently attempted to use
this observation as a basis for screening. A specific test was not
developed until Davidsohn4567
modified the procedure by
introducing differential absorption steps to eliminate Forssman and
serum sickness antibody confusion. The Davidsohn test procedure is
accepted as the classic reference method in detecting IM.
The Plasmatec IM latex test
provides a suspension of polystyrene latex particles which have been
coated with partially purified glycoprotein from bovine red blood
cells. The heterophile antibody associated with IM blinds to the
corresponding antigenic determinants on the glycoprotein coated
latex. Due to the purification of the bovine red blood cell, the
glycoprotein coated latex is not agglutinated by Forssman or serum
sickness antibodies at levels normally encountered in the U.K.
population; therefore, no differential absorption is required.
Utilising our Plasmatec test
serum found positive for IM which contains heterophile antibody
associated with IM binds to the corresponding antigenic determinants
on the glycoprotein coated latex forming visible macroagglutination.
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