IgE levels correlate with FcεRI expression on circulatory basophils but not with their activation response in patients with Hymenoptera anaphylaxis.

BACKGROUND

Measurement of IgE levels, skin prick tests (SPT), and basophil activation tests (BAT) are the gold standards for diagnosing Hymenoptera allergy. Currently, BAT most accurately resembles patient reactivity. However, data examining the influence of serum IgE and basophil FcεRI expression on BAT performance and their clinical relevance are limited.

METHODS

Total and specific IgE (sIgE) levels and their ratios, SPT results, high-affinity IgE receptor (FcεRI) expression on basophils, and BAT results from 31 patients with Hymenoptera-induced anaphylaxis were analyzed and correlated with clinical data.

RESULTS

The sIgE/IgE ratio correlated with positive SPT results at lower venom concentrations in patients with wasp allergy but not in those with bee allergy. Total IgE levels did not correlate with SPT reactivity but correlated with the total (r = 0.742, p < 0.01) and IgE-unoccupied FcεRI (r = -0.796, p < 0.01) expression on basophils. The sIgE/IgE ratio significantly correlated with the effector concentration 50 (EC50) at lower wasp venom concentrations and tended to correlate with maximal basophil activation in BAT. A high anaphylaxis grade was associated with low total IgE and high unoccupied FcεRI levels in patients sensitized to wasp venoms. Furthermore, elevated tryptase levels were associated with low total IgE and FcεRI levels but high unoccupied FcεRI levels.

CONCLUSIONS

sIgE levels, rather than total IgE levels, can be indicative of functional test results, such as SPT and BAT, in patients allergic to wasp venom but not in those allergic to bee venom. Other activation mechanisms may account for the observed discrepancies in patients allergic to bee venom and should be explored further.