|
Summary.
Specific diagnosis
of immediate type
allergies, such as
rhinoconjunctivis,
asthma, urticaria/angioedema
and anaphylaxis,
particularly when
IgE-mediated,
traditionally rests
on prick and/or
intradermal skin
tests and, since
about 30 years, on
the determination of
allergen specific
IgEs. Some cellular
tests, i.e. tests
determining the
reactivity of blood
cells in vitro,
particularly
basophils, to
allergens, have been
available for many
years. The
determination of
histamine release
has been widely used
in allergy
pathophysiological
research but its
routine application
in allergy diagnosis
has been restricted
to few groups.
Basophil
degranulation, as
determined by
microscopic
examination, was
promoted by some
groups in the 1980s
but has been largely
abandoned since
around 10 years ago;
an alternative
cellular test, based
on the determination
of
sulfidoleukotrienes
(LTC4, LTD4, LTE4)
produced by IL-3
primed basophils
stimulated by
allergens in vitro,
has been proposed.
This test became
available
commercially in 1993
under the name of
CAST (Bühlmann
Laboratories,
Allschwil,
Switzerland).
The CAST assay has
been used in allergy
diagnosis in a
variety of
indications, such as
inhalation allergies,
allergies to insect
venoms, foods,
occupational
allergens and
various drugs. A
large number of
reports on CAST
diagnostic value,
however, have been
anecdotal. A meta-analysis
of validated and
well controlled
studies encompasses
37
studies, 1614
patients and 1145
controls. This
should definitely
establish the value
of this diagnostic
test, particularly
in instances where
other in vitro or in
vivo diagnostic
tests are not
reliable, such as
food or drug
allergies, as well
as in non-IgE-
mediated immediate
hypersensitivity
reactions. However,
a number of
questions about the
CAST diagnostic
assay are still open
or have not been
systematically
explored. This may
explain, in addition
to the practical
limitations inherent
to all allergy
cellular tests, why
CAST has not yet
become a very widely
used assay worldwide,
having gained broad
acceptance in some
countries but not in
others.
Key words:
Sulphidoleukotriens,
CAST, allergy, in
vitro diagnosis |
