Psoriasis and IgE-mediated allergy: correlation or mutual inhibition?: A prospective cohort study in patients with mild or moderate to severe psoriasis

Summary Background Psoriasis is an autoimmune disease caused by overactivation of T H 1 (Type 1 helper cells) and T H 17 (T helper 17) cells. Overactivation of T H 1 cells inhibits the activity of T H 2 cells involved in type 1 allergies, therefore, psoriasis patients might be less affected by type 1 allergies. This study tested if allergies were less frequent in patients with moderate to severe than with mild psoriasis. Methods Psoriasis patients at the study site reported possible allergy symptoms and were tested for common allergens by skin prick test and IgE levels. Psoriasis was classified by PASI scores (Psoriasis Area and Severity Index) as mild (PASI