Association between Serum IL-16 Levels and the Degree of Sensitization in Patients with Atopic Dermatitis

Abstract

Background: Interleukin (IL)-16 has been characterized as an immunomodulatory cytokine. Besides its chemotactic properties, IL-16 amplifies inflammatory processes and possesses immunoregulatory functions. Our aim was to investigate the association between serum IL-16 levels and the degree of allergic sensitization in patients with atopic dermatitis (AD). Methods: The serum level of IL-16 was measured by immunoenzymatic assays. Eosinophil cell count, serum total and specific IgE levels were assessed; prick tests were also carried out. Based on specific IgE levels and prick tests, AD patients were divided into sensitized and nonsensitized subgroups, and correlations among serum IL-16, total IgE levels and eosinophil cell counts were measured in the total patient group and in subgroups. Results: In the total patient group, significantly higher levels of IL-16 were found in the sera of patients with AD, compared to healthy individuals and patients with psoriasis. A significant correlation was detected between serum levels of IL-16 and total IgE, total IgE and eosinophil counts, but not between IL-16 and eosinophils. When sensitized and nonsensitized subgroups were compared, IL-16 levels showed a significant difference in subgroups that were divided based on specific IgE measurements, but not in those subgroups which were divided based on prick tests. On the other hand, serum total IgE levels showed a significant difference between sensitized and nonsensitized subgroups, assessed by the specific IgE method and also by prick test. Conclusion: Serum IL-16 levels of AD patients correlate to some extent with sensitization. This correlation is not as strong as the correlation between total IgE levels and allergic sensitization.