Exploring the Role of Leukocyte Adherence Inhibition Test in Assessing Non-IgE Mediated Immunoreactivity to Benzoic Acid in Allergic Patients

Background: Several publications report benzoic acid as responsible for non–IgE-mediated allergic reactions. No standardized lab exam identifies these reactions besides in vivo provocation tests.

Aim: To evaluate the potential of the Leukocyte Adherence Inhibition Test (LAIT) to discriminate non–IgE-mediated immunoreactivity against benzoic acid in patients with non–IgE-mediated allergic phenotypes.

Study Design: We retrospectively examined the medical charts of 100 patients diagnosed with allergic rhinitis, allergic bronchitis, asthma, sinus headache, atopic dermatitis, and/or urticaria with clinical suspicion of non–IgE-mediated benzoic acid hypersensitivity who were investigated with ex vivo challenge test monitored by LAIT against benzoic acid. The cohort counted 30 males; the mean age was 41.9 years, the SD was 20.4 years, and the range was 2 to 90 years.

Place and Duration of Study: Instituto Alergoimuno de Americana – São Paulo – Brazil – between January 2018 and March 2024.

Methodology: The percentage of Leukocyte Adherence Inhibition (LAI) promoted by the ex vivo challenges against 1 mg/mL benzoic acid was distributed in ranges through a cascade distribution chart to outline the variability of the results.

Results: The LAI ranged from 0% to 97%; the Mean was 41.1%; the Median was 40.5%; the Standard Deviation was 24.2%; the Mode was 0 and 59 (each appeared four times). The cascade distribution demonstrates a wide distribution of LAI results. This extensive distribution of LAI results suggests that some patients had mild, moderate, or severe non–IgE-mediated immunoreactivity against benzoic acid, while others did not present any immunoreactivity against it.

Conclusion: Our preliminary results support that the LAIT performed with benzoic acid may discriminate diverse degrees of ex vivo immunoreactivity in patients suffering from diversified allergic phenotypes. It is worth carrying out more in-depth studies to evaluate the usefulness of LAIT in diagnosing non–IgE-mediated benzoic acid allergies.