Role of Odorant-Binding Protein in Allergy to Cow Epithelium

Abstract

Introduction: In a previous study conducted by the Allergy Section of the HULA, sensitization to an undescribed 25-kDa protein was detected in patients allergic to cow epithelium. Mass spectrometry identified the protein as an odorant-binding protein (OBP), a lipocalin from Bos taurus. Although its association with symptoms has not been proven, recent research suggests that its inclusion in extracts for diagnosis and treatment could be beneficial. This study aimed to evaluate the role of OBP in cow epithelium allergy (CEA) in sensitized patients.

Methods: This was a descriptive, cross-sectional, observational study of a case series, including a total of 17 patients with confirmed sensitization to cow allergens by immunoblotting. From this cohort, seven participants were selected for further analysis. Data collected included age, sex, occupation, years of exposure, test results, and the group classification to which each participant belonged. OBP was purified and isolated from bull urine, and a lyophilized extract was prepared for skin testing and conjunctival provocation.

Results: Skin prick tests with purified OBP were positive in 6 of 7 patients with bovine epithelium allergy. Conjunctival allergen provocation tests were positive in 4 out of 6 patients. All controls were negative in both tests.

Conclusion: OBP behaves as a major antigen in this cohort of CEA patients. This is the first study to establish the independent clinical relevance of bovine OBP in CEA, paving the way for improved diagnostic and therapeutic protocols.

Keywords: Cow epithelium allergy; Lipocalin; Odorant-binding protein; Rhinoconjunctivitis; Sensitization.