M2 macrophage polarization in chronic spontaneous urticaria refractory to antihistamine treatment

Dear Editor, Mast cells are the main effector cells in urticaria, and interact with various cells in the dermal microenvironment, such as macrophages, which form an essential component of innate immunity, and are involved in numerous functions including protein secretion. Macrophages perform two main functions and recently two phenotypic macrophage variants, called M1 and M2, have been characterized and linked to the type of response they can orchestrate; (i) M1 populations, that has a killer function; eliminate a pathogen or defective cell, or (ii) M2 macrophages, also named as "alternatively activated macrophages", that produces repair function that involves the regulation of immune response, angiogenesis, and healing and promotes a TH2 response, as well was considered immunosuppressive, and leads to a worse response in eosinophilic or allergic diseases, such as nasal polyposis and asthma. Our study aimed to characterize the presence and phenotype of macrophages in lesions of chronic spontaneous urticaria (CSU) patients nonresponsive to treatment with antihistamines at optimized doses (fourfold doses), and to compare to control skin, as well with clinical and laboratory parameters.