Serum leptin levels in patients with pollen-induced allergic rhinitis

Background: Several studies have outlined a possible relationship between an increased body mass index (BMI) and respiratory allergic diseases, such as asthma and rhinitis. The aim of the study was to evaluate the serum leptin levels in a cohort of patients with pollen-induced allergic rhinitis, enrolled outside the pollen season, and in a group of healthy controls. Methods: The study included 75 subjects: 41 patients with moderate-severe persistent allergic rhinitis due to a pollen allergy and 34 normal subjects. All subjects were prospectively and consecutively evaluated. A skin prick test and blood sampling for assessing serum leptin levels, eosinophils, specific IgE, and nasal challenge were performed in all subjects. Results: After analyzing genders separately, female allergic patients showed significantly higher levels than normal females (p = 0.031), whereas the comparison between allergic and normal males was not significant (p = 0.9651). Leptin serum levels were significantly related with age in normal (p = 0.0059) and allergic (p = 0.0042) females. In addition, BMI and leptin levels were significantly correlated (p = 0.01) in all allergic patients; there were other significant relationships between leptin levels and symptom severity in females (p = 0063, r = 0.68), peripheral eosinophils in males (p = 0.023, r = 0.49), and allergen threshold dose at nasal challenge in both genders (males: p = 0.0001, r = -0.85; females: p = 0.0001, r = -0.95). Conclusions: This preliminary study provides the first evidence of significantly higher leptin serum levels in female patients with pollen-induced allergic rhinitis outside the pollen season.