Low Responsiveness of Basophils via FcεRI Reflects Disease Activity in Chronic Spontaneous Urticaria

The insufficient effect of H1-antihistamine in some patients with chronic spontaneous urticaria (CSU) suggests that factors other than histamine are involved in the pathophysiology of CSU. Moreover, a central role for basophils in the pathophysiology of CSU has been hypothesized. However, few studies have focused on the relationship between basophil reactivity via FcεRI and clinical features in patients with CSU.

To assess basophil reactivity via FcεRI against anti-IgE and FcεRI stimulation in patients with CSU, and its association with disease activity in CSU. FcεRI expression and IgE binding on basophils from patients with CSU were also investigated.

We analyzed 38 patients with CSU, 8 patients with atopic dermatitis (AD), and 11 healthy controls (HCs). The surface CD203c expression with or without anti-IgE or FcεRI stimulation, and IgE and FcεRI (CRA1, CRA2) expression on blood basophils were evaluated. Patients with CSU were also evaluated and classified by disease activity and the above parameters were compared.

The proportion of CD203c^high basophils after anti-IgE or anti-FcεRI stimulation was lower in patients with CSU compared with HCs and patients with AD. It was lowest in the CSU group with severe disease. Basophils from patients with CSU had higher FcεRI (CRA1) expression, although it was not closely related to the severity of CSU. Subgroup analysis revealed that patients with CSU showing low responsiveness of basophils via FcεRI exhibited a short duration of disease but severe disease activity.

Low reactivity of basophils via FcεRI is characteristic of patients with CSU. This attenuated reactivity is associated with severe clinical activity in patients with CSU (250 of 250).