Immunochemical Determination of IgE and IgG Autoantibodies in Patients with Chronic Spontaneous Urticaria: A Narrative Review

Background/Objectives: Chronic spontaneous urticaria (CSU) is characterized by almost daily wheals or angioedema lasting for more than six weeks and not attributable to a defined inducing factor. CSU reportedly affects 1–2% of the general population and may lead to a substantial impairment in patients’ quality of life. Thus, developing methods that enable early diagnosis and assessment of disease activity is a major objective for scientists and clinicians. Methods: A significant proportion of CSU cases appears to be associated with autoimmune mechanisms, which mainly involve IgE autoantibodies (type I CSU), IgG autoantibodies (type IIb CSU), or both (type I and type IIb overlap). To this end, detection of specific IgE and/or IgG autoantibodies in CSU patients using biological or immunochemical assays can offer valuable information and enable further investigation and better management of the disease. Results: This review focuses on and presents various immunochemical assays, mainly ELISAs, for determining specific IgE and/or IgG autoantibodies, along with immunochemical methods for quantifying total IgE levels as an additional biomarker in CSU patients; the development and/or application of these assays has been reported in several papers published in the last decade on CSU. Conclusions: The methods presented have recently been applied and have substantially contributed to CSU diagnosis, endotyping and prediction of response to various treatments. Further validation of the existing immunochemical assays along with the development of reliable assays for novel autoantibodies and/or autoantigens will deepen our understanding of CSU pathogenesis and support the clinical diagnosis and treatment of CSU.