Mediators of the homeostasis and effector functions of memory Th2 cells as novel drug targets in intractable chronic allergic diseases.

Allergic patients have life-long chronic inflammatory diseases with repeated relapses and exacerbations. Currently used allergy therapeutics have some limitations, which warrants a search for novel drug targets for allergy treatment. The studies on conventional allergic disease therapeutics have been focused on the pathology of allergy involving effector type 2 helper T cells (Th2). However, it has been suggested that allergen-specific memory Th2 cells are developed after the initial allergen exposure, which may play a critical role in the allergic relapses. Here, we discuss the contribution of memory Th2 cells to allergic diseases and the microenvironmental factors for chronic allergic disease persistence. Since most allergy drugs are prescribed to suppress symptoms of the diseases, targeting the different types of cells or factors contributing to allergic diseases persistence may cure the disease.