In the last few years, it has become extensively recognized that a part of chronic spontaneous urticaria (CSU) cases are of autoimmune origin. The search for a reliable diagnostic tool to confirm the underlying autoimmune pathophysiology is still ongoing. Recently, the CD63 basophil activation test (CD63 BAT) has become a useful tool for diagnosing autoimmune CSU.

The objective of this study is to analyze the association between positive results of CD63 BAT, total IgE antibody levels, and the incidence of autoimmune thyroiditis as a comorbidity in CSU patients. A retrospective analysis of CD63 BAT results from 87 CSU and 20 non-CSU patients was performed. The data extracted from the patients records consisted of age, gender, clinical history of autoimmune thyroiditis (AT), total IgE levels and the presence of anti-thyroid autoantibodies.

The results of the study showed that positive CD63 BAT results were significantly more frequent in CSU patients as compared with non-CSU subjects (p=0.045). Moreover, a significant negative association between the stimulation index (SI) value for CD63 BAT and total IgE levels in CD63 BAT-positive CSU patients (p=0.004) was also seen. This outcome means that higher SI values are related to lower total IgE values, and vice versa.

The study concluded that the existing standard set of diagnostic tools is not reliable to determine when CSU is caused by autoimmune mechanisms. CD63 BAT represents a helpful diagnostic tool for identifying underlying autoimmunity, as the evidence suggests. The results have shown that high SI values in CD63 BAT-positive CSU patients relate negatively with their total IgE levels.

Source: HOssein Zadeh Attar M, Merk HF, Kotliar K, et al. The CD63 basophil activation test as a diagnostic tool for assessing autoimmunity in patients with chronic spontaneous urticaria. Eur J Dermatol. 2019;29(6):614-618. doi:10.1684/ejd.2019.3680