The use of basophil activation test in clinical practice
The BAT can have different applications in the day-to-day clinical
setting - Table 2 summarises some of the possible indications
of BAT, which can be categorized into three main groups: 1) confirmation
of an allergy, 2) eligibility for a specific therapy and 3) monitoring
of the natural resolution of an allergy or response to therapy. The
confirmation of allergy is important for several reasons. Firstly, it
improves the safety profile of diagnostic work-up, as it may defer the
need for an oral food challenge, preventing potential anaphylactic
reactions. Secondly, it allows confirming the indication for immune
modifying therapies that may require prolonged exposure to medications
before a clinical response is seen. Examples for this is the use of
omalizumab in allergic asthma and initiation of oral food immunotherapy,
both of which require many months on therapy to assess response.
Thirdly, BAT may be useful to measure the response to treatment and act
as a surrogate of in vivo allergen exposure, like in a food challenge.
Even in cases where basophils show no response to allergen and the
positive control, IgE (known as non-releaser or anergic basophils),
data is emerging that is suggestive of this finding is more likely to
indicate low clinical reactivity to allergen (24). Furthermore, BAT also
has value in rare allergic disorders, such as allergic bronchopulmonary
aspergillosis, as an additional criterion for diagnosis, particularly in
patients who do not fulfill the minimal diagnostic criteria.
The use of the BAT to clinical practice requires analytical validation
of the methodology, clinical validation of the test against patients’
phenotype and continued quality assurance57,87-89.