Cellular basophil activation tests (BAT) such as histamine or sulfidoleukotriene-release tests for allergy diagnosis have been available for
some time, but expression of basophil-activation markers such as CD63 and CD203c detected by flow cytometry has attracted particular
attention in recent years. Not only the potential but also the possible pitfalls of flow-cytometric BAT have been stressed recently. Some
authors have suggested that the technical problems are still such that BAT should only be performed in specialist laboratories.
In an earlier review based on our clinical experience obtained over several years, we showed that, even using different protocols, reproducible
and meaningful clinical results can be obtained. In this paper, we review the current knowledge in relation to several technical issues and
show that flow-cytometric BAT already represents a major advance in the field of in vitro allergy diagnosis. We conclude that there are
no serious technical justifications for depriving allergic patients of clinically indicated BAT tests, which can be performed reliably by any
laboratory with the appropriate experience in allergy diagnosis and flow cytometry.

Key words: Basophil activation test. Allergy diagnosis. CD63. CD203c. Technical issues.