Background: Immunoglobulin (Ig)E-sensitized persons with positive skin prick test, but no allergy symptoms, are classified as being asymptomatic skin sensitized (AS). The allergic type 1 disease is dependant on IgE binding to the high affinity IgE-receptor (FcɛRI) expressed on basophils and mast cells. However, a relationship between the AS status and FcɛRI has not been investigated. We aimed to characterize basophils from AS by looking at histamine release (HR) (sensitivity and reactivity) and the FcɛRI molecule, and compare it with nonatopic (NA) or allergic (A) persons.
Methods: Blood was obtained from NA (n = 14), grass and/or birch A persons (n = 17) and mono-sensitized grass or birch pollen AS (n = 12). The basophil sensitivity and reactivity were examined by anti-IgE triggered HR. Surface expression of FcɛRI and IgE were measured by flow cytometry, FcɛRIα protein was identified using a radioimmunoassay and Western blot. mRNA coding for the classic FcɛRIβ-chain and the truncated form (FcɛRIβT) were determined by real-time PCR.
Results: The AS group was less reactive than NA or A persons when triggered by anti-IgE and had a significant higher number of nonresponders. However, there was no difference in sensitivity among the three groups and furthermore; the groups did not vary in FcɛRI- and IgE-surface expression, FcɛRIα-protein level or β/βT ratio.
Conclusion: Basophils from AS persons are less reactive and include more nonresponders than basophils from NA and A persons, but do not differ regarding the FcɛRI molecule.