Gene profiling in active dermatitis lesions strengthens the diagnosis of allergic contact dermatitis

Background: Distinguishing between allergic and nonallergic forms of Contact Dermatitis (CD) is challenging and requires investigations based on patch -testing. Early detection of allergy biomarkers in active CD lesions could refine and simplify the management of CD patients. Objective: To characterize the molecular signatures of active CD lesions. Methods: We studied the expression of 12 allergy biomarkers by qRT-PCR in active lesions of 38 CD patients. Allergic CD (ACD) was diagnosed based on patch test (PT) results and exposure assessment. Molecular signatures of active lesions, as well as positive PT reactions, were compared with those of reference chemical allergens and irritants. Results: Nineteen of the 38 CD patients reacted positively upon patch -testing and exposure assessment confirmed ACD diagnosis for 17 of them. Gene profiling of active CD lesions revealed 2 distinct molecular patterns: patients harboring signatures similar to reference allergens ( n = 23) or irritants ( n = 15). Among the 23 patients with an "allergy signature,"we found the 17 patients with confirmed ACD, while no culprit allergen was identified for the 6 other patients. Interestingly, the 15 patients without biomarker induction had negative PT, suggesting that they developed nonallergic CD reactions. Conclusion: Molecular signatures from active skin lesions may help to stratify CD patients and predict those suffering from ACD. ( J Am Acad Dermatol 2024;90:953-62.)