Distinct Clinical Profiles of IgE and IgG Autoantibodies to Thyroid Peroxidase in Chronic Spontaneous Urticaria

Purpose: In chronic spontaneous urticaria (CSU), autoimmune thyroid disease is the most common autoimmune comorbidity, and many CSU patients have immunoglobulin (Ig)E or IgG autoantibodies to thyroid peroxidase (TPO). It remains unclear how anti-TPO IgE and IgG autoantibodies are linked to each other and are associated with CSU features, activity, and therapeutic responses. Methods: CSU patients (n = 146, 92 females, mean age 42.9 years) and healthy normal controls (NCs, n = 30) were assessed for anti-TPO IgE and IgG by enzyme-linked immunosorbent assay, and the clinical and laboratory profiles, disease activity (UAS7), and response to 3 months of H1-antihistamine treatment were evaluated for anti-TPO IgE-positive and/or IgG-positive patients. Results: Among 146 CSU patients, 67 (46%, NCs: 6.6%) had elevated anti-TPO IgE and/or IgG, and 32 (22%), 35 (24%), and 5 (3%) had elevated anti-TPO IgE, anti-TPO IgG, and both, respectively. Of the patients with anti-TPO IgE and/or IgG, 44% (n = 27) had anti-TPO IgE but not IgG, 48% (n = 30) had anti-TPO IgG but not IgE, and only 8% (n = 5) had anti-TPO IgE and IgG. Compared to anti-TPO IgE-negative patients, anti-TPO IgE-positive ones had greater rates of atopy and antihistamine responses and lower disease activity (UAS7). Anti-TPO IgG-positive patients had greater rates of angioedema and elevated levels of anti-thyroglobulin IgG than anti-TPO IgG-negative patients. Conclusions: Forty-six percentages of CSU patients have autoantibodies to TPO; most have either IgE or IgG autoantibodies but not both. Anti-TPO IgE and anti-TPO IgG come with distinct CSU profiles, including treatment responses.