LAUSR

Allergic diseases, including allergic rhinitis (AR), asthma, anaphylaxis, food allergies, atopic dermatitis (AD), and drug allergies, are a group of disorders caused by hypersensitivity of the immune system to innocuous environmental antigens (1). These diseases represent a global public health problem affecting up to 50% of the world population, and the prevalence of allergic diseases has been increasing, especially in developing countries (2). While Type 2 T helper (TH2) cells have long been believed to play a pivotal role in allergic immune responses, growing evidence has suggested a more complex mechanism underlying the pathogenesis of allergic diseases (1). Allergen immunotherapy (AIT) is the only medical intervention that can modify the natural course of allergic diseases. To date, there are no validated biomarkers to monitor the clinical response to AIT and the mechanisms of allergy tolerance after AIT remain poorly understood (3, 4). In recent years, the immunological mechanisms underlying allergic diseases have received increasing attention. The emerging roles of innate lymphoid cells (ILCs), T follicular helper (Tfh) cells, and B regulatory (Breg) cells in the development of allergic diseases have been identified (1, 5, 6). A better understanding of the immunological mechanisms of allergic diseases is vital to developing novel therapy and biomarkers of efficacy. Our Special Research Topic “The Spectrum of Lymphoid Subsets in Allergic Diseases: Immune Regulation and Immunotherapy”, compiles views from several outstanding experts in the field. Here, we discuss the main messages from four original research articles and one review article, as reported below. Both T and B cells are believed to contribute to the pathogenesis of AD; however, the participation of novel lymphoid subsets, Tfh and Breg cells, and their interactions in childhood AD are unclear (7). Jiang et al. observed lower frequencies of CD19IL-10 Breg cells and higher frequencies of CD4CXCR5PD-1ICOS Tfh cells in children with extrinsic AD than healthy controls (Jiang et al.). The frequencies of CD19IL-10 Breg cells correlated negatively with disease activity in children with extrinsic AD, indicating a role of Breg cells in regulating pathogenesis and disease progression of extrinsic AD (Jiang et al.). In addition, Breg cells from patients with extrinsic AD have compromised ability in inhibiting the differentiation of Tfh cells in vitro. This phenomenon may be associated with IL-10 deficiency in Breg cells (Jiang et al.).