Urticaria
Urticaria is a skin condition that is defined by the occurrence of itchy hives and/or angioedema.1
Hives are itchy, raised patches on the skin that can vary in shape, size and color. They can appear anywhere on your body and can be sometimes painful.1,2
Many people with urticaria also experience pronounced swelling of the deeper layers of the skin.1 This is called angioedema, and most commonly affects the eyelids, lips, genitals, tongue, hands and feet.3
1.Zuberbier T, et al. Allergy. 2022; 77:734-766;
2. Maurer M, et al. World Allergy Organ J. 2018 Nov 16;11(1):32;
3. Axelrod S, Davis-Lorton M. Mt Sinai J Med 2011;78(5):784–802
Urticaria is classified as acute (symptoms last less than 6 weeks) or chronic (≥ 6 weeks)1.
Chronic urticaria is further classified as spontaneous (CSU) which shows with hives, angioedema or both with known and unknown causes and no identifiable external trigger and inducible (CINDU) in which an identifiable trigger is documented. CINDU has several forms such as symptomatic dermographism, cold urticaria, delayed pressure urticaria, solar urticaria, heat urticaria, and vibratory angioedema (collectively referred to as chronic physical urticaria), as well as cholinergic urticaria, contact urticaria, and aquagenic urticaria.1
1. Zuberbier T, et al. Allergy. 2022; 77:734-766
The worldwide prevalence of CSU is approximately 0.7–1.4%1. All age groups can be affected, but the peak incidence is seen between 20 and 40 years of age2. Women are twice more likely to experience urticaria than man2.
Duration of CSU is generally 2–5 years but some patients suffer well beyond 5 years3. It is likely to be longer in patients with higher disease activity2,4, concurrent angioedema 2,4, concurrent inducible urticaria2 and in patients with autoreactivity2.
Patients with CSU are often affected by the unpredictability of symptoms and distressed by their inability to engage in everyday living activities due to the spontaneous nature of outbreaks. Furthermore, patients with CSU experience distressing symptoms that can cause negative effects on quality of life, anxiety, depression, and considerable humanistic and economic impacts 2,5,6. CSU is associated with a quality of life impairment similar to or greater than that of atopic dermatitis, psoriasis, and other chronic dermatologic conditions6.
1. Fricke J, et al. Allergy. 2020;75:423–32;
2. Maurer M, et al. Allergy. 2011;66:317−30;
3. Saini S and Kaplan A. J Allergy Clin Immunol Pract. 2018;6:1097–106;
4. Toubi E, et al. Allergy. 2004;59:869−73;
5. Maurer M, et al. Allergy. 2017;27:2005–16;
6. Balp M, et al. 2015;8:551–8; 6. Grob J, et al. Br J Dermatol. 2005;152:289–95
The symptoms of CSU are caused by mast cell activation leading to the release of pro-inflammatory mediators (such as histamine and cytokines) and subsequent vasodilation, increased vascular permeability and stimulation of sensory nerve endings1.
FcεRI receptors are found on immune effector cells such as mast cells and basophils and bind IgE with high affinity to form IgE-FcεRI complexes1,2. Cross-linking of two FcεRI molecules activates the FcεRI signaling cascade, leading to mast cell activation and the release of intracellular mediators that result in the symptoms associated with CSU1,2.
In CSU, FcεRI activation of mast cells can be triggered by two autoimmune reactions, both of which involve cross-linking of FcεRI-bound IgE3:
- Type I: mast cell activation by auto-antigen cross-linking of FcεRI-bound IgE3
- Type IIb: mast cell activation by IgG anti-FcεRI cross-linking of FcεRI, or mast cell activation by IgG anti-IgE cross-linking of FcεRI-bound IgE3
1. Altman K and Chang C. Clin Rev Allergy Immunol. 2013;45:47−62;
2. Wernersson S and Pejler G. Nat Rev Immunol. 2014;14:478–94;
3. Kaplan A and Greaves M. Clin Exp Allergy. 2009;39:777–87
