Association between IgG Autoantibodies to Cytokeratin 18 Protein and Clinical Severity in Adult Asthmatic Patients

Abstract

Background: Cytokeratin 18 (CK18) protein was identified as an airway epithelial cell antigen associated with nonallergic asthma. Objective: We evaluated an association between IgG autoantibodies to CK18 protein and clinical severity of asthma in this study. Methods: Severe asthma was defined as when patients had experienced at least one severe asthmatic exacerbation requiring an emergency room visit or admission in the last year despite continuous typical therapies. Moderate asthma was defined as when patients had been controlled by typical therapies without severe asthmatic exacerbation in the last year. Mild asthma was defined as when patients experienced intermittent asthmatic symptoms and did not need continuous anti-asthmatic treatments in the last year. IgG autoantibodies to CK18 protein were detected in serum samples by immunoblot analysis. Results: IgG autoantibodies to CK18 protein were detected in 48 of 161 asthmatic patients (29.8%) and 5 of 58 healthy controls (8.6%) (P=0.002). IgG autoantibodies to CK18 protein were detected in 1 of 20 patients with mild asthma (5.0%), 22 of 63 patients with moderate asthma (34.9%), and 25 of 78 patients with severe asthma (32.1%)(P<0.001). Conclusion: These findings suggest that IgG autoantibodies to CK18 protein could be a biological marker for moderate- to-severe asthma requiring continuous medical treatment.