| Pernicious
Anaemia Intrinsic
Factor antibodies (IFAB)
Biermer’s
anaemia is the disease most frequently
associated with vitamin B12 deficiency.
This disease shows the classical features
of megaloblastic anaemia (i.e. morphologic
and functional abnormalities of the blood
cells and marrow precursors related to
impairment of DNA synthesis).
Pernicious
anaemia is charcterised by a gastric mucosal
defect that decreases the synthesis of
intrinsic factor. Since this glycoprotein
plays an essential role in the transport
and absorption of vitamin B12 across the
small intestine, patients affected by
pernicious anaemia show severe decreases
in serum vitamin B12 levels. The presence
of auto-antibodies against gastric parietal
cell cytoplasm, thyroid components and
intrinsic factor, strongly suggest an
auto-immune process to the disease.
Two
types of anti-intrinsic factor auto-antibodies
have been described. The blocking auto-antibodies
(type I) hinder the binding of vitamin
B12
complexes. Such antibodies are frequently
encountered in patients affected by pernicious
anaemia. Binding auto-antibodies (type
II) that bind to the intrinsic factor
as well as to the IF/vitamin B12 complexes
preventing their absorbance, have also
been described. Detection
of anti-intrinsic factor antibodies provides
an important contribution to the differential
diagnosis of pernicious anaemia (due to
intrinsic factor deficiency) and other
causes of vitamin B12 malabsorption. Indeed,
other tests such as cytomorphology of
red blood cells, determination of serum
vitamin B12 levels or the Schilling test
are not specific enough for the diagnosis
of a Biermer’s anaemia. Anti-intrinsic
factor antibodies can be detected using
two types of methodologies: RIA or ELISA
methods. The ability of type I auto-antibodies
to prevent the binding of vitamin B12
to the intrinsic factor has allowed the
development of RIA methods. Such methods,
however, only detect type I auto-antibodies.
Moreover, they are subject to interferences
induced by exogenous sources of vitamin
B12 that may induce false positive results
(especially in the case of vitamin
B12
treatment, or when the sample is taken
after a Schilling test).
ELISA
methods detect type I and type II antibodies
and are unaffected by the presence of
the endogenous vitamin B12 levels. The
AUTOZYME™ IFAB Anti-Intrinsic Factor Antibodies
Assay is an easy, rapid and sensitive
method allowing the detection of total
anti-intrinsic factor antibodies. The
use of purified intrinsic factor as antigen
ensures the specificity of the method.
AUTOZYME™
- the next generation of Enzyme Immunoassays
This
assay has been designed for the modern
laboratory with flexibility in mind. It
can be used in manual mode or with automated
instrument systems. The AUTOZYME™ system
employs ready-to-use colour coded reagents
resulting in less "hands on"
time. Break-a-well strips ensure flexibility
and economic use for any batch size so
that patient turn around time can be speeded
up. Kit controls coupled with high purity
antigens ensure the method is valid and
specific.
This
format offers:
- manual
or automated methodology
- colour-coded
reagents
- break-a-well
flexibility
- long
shelf-life
- kit
controls provided
- high
purity antigens
- rapid
patient results
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