Orchestration between ILC2s and Th2 cells in shaping type 2 immune responses

The type 2 immune response is critical for host defense against large parasites such as helminths.On the other hand,dysregulation of the type 2 immune response may cause immunopathological conditions,including asthma,atopic dermatitis,rhinitis,and anaphylaxis.Thus,a balanced type 2 immune response must be achieved to mount effective protection against invading pathogens while avoiding immunopathology.The classical model of type 2 immunity mainly involves the differentiation of type 2 T helper(Th2)cells and the production of distinct type 2 cytokines,including interleukin-4(IL-4),IL-5,and IL-13.Group 2 innate lymphoid cells(ILC2s)were recently recognized as another important source of type 2 cytokines.Although eosinophils,mast cells,and basophils can also express type 2 cytokines and participate in type 2 immune responses to various degrees,the production of type 2 cytokines by the lymphoid lineages,Th2 cells,and ILC2s in particular is the central event during the type 2 immune response.In this review,we discuss recent advances in our understanding of how ILC2s and Th2 cells orchestrate type 2 immune responses through direct and indirect interactions.