Backgrounds:~Urticaria is a common disorder that present with localized edema reaction caused by dilatation and increased permeability of small blood vessels in skin and mucosa. The main clinical manifestations are wheal and erythema reaction.~Chronic spontaneous urticaria (CSU) is defined as the recurrent, transient (<24h), pruritic wheals of the skin and mucosa lasting for more than 6 weeks ,with or without angioedema, excluding chronic inducible urticaria and urticarial vasculitis. Among all patients with chronic urticaria, CSU patients accounts for about 80%. Although the pathogenesis of CSU is still unclear, increasing evidence has shown an autoimmune feature of this chronic disease. Oral antihistamines are the mainstay of treatment for patients with CSU. However, a proportion of patients with CSU remain symptomatic despite treatment with standard- or doubled-dose of antihistamines. In recent years, studies have shown that low-dose recombinant human IL-2 (rhIL-2) treatment has good therapeutic effect in a variety of autoimmune diseases, such as systemic lupus erythematosus, type 1 diabetes, without serious side reactions. Therefore, we propose low-dose rhIL-2 as an add-on treatment for patient with CSU that are recalcitrant to treatment with antihistamines. Here we designed this clinical trial to explore its therapeutic effect as well as therapeutic mechanisms.~Design of Study:~This is a randomized, controlled, single-center clinical trial to assess the short-term efficacy of rhIL-2 treatment for patients with CSU.~Methods:~RhIL-2 injection combined with the current dose of antihistamine (Use one kind or two to three kinds in combination, and use one or two doses of each kind of antihistamine，keeping doses before enrollment) will be applied to CSU patients meeting the inclusion criteria. The end points include clinical response and immunological changes, as well as safety.
This study is a randomized, controlled, single-center clinical study to evaluate the short-term efficacy of low-dose Interleukin-2 injection as an add-on therapy for the treatment of patients aged 18-75 who have been diagnosed with CSU and remain symptomatic despite oral antihistamine treatment .