Fig. 1

Eosinopoiesis, its transcription factors, and eosinophil chemotaxis to the blood and tissue and their function in type 2 immunity. IL-5 is pivotal in stimulating eosinopoiesis and recruiting mature eosinophils to tissue with CCL11, which is produced from fibroblasts and epithelial cells. Type 2 innate lymphoid cells (ILCs) and dendritic cell- (DC) activated Th2 cells are important eosinophil activation and recruitment routes while pathogens directly stimulate eosinophils. Damaged endothelial and epithelial cells, fibroblasts, and adipocytes kickstart the process by secreting alarmins that stimulate IL-5 production from type 2 ILCs. On the other hand, mature DCs help with T helper 2 (Th2) polarization. Eosinophils typically release their mediators via the classical exocytosis, or the release of intact granules upon their lysis (cytolysis), or piecemeal degranulation (PMD) which is the most popular method. LT-HSC long-term hematopoietic stem cell, GMP granulocyte-monocyte, MBP major basic protein, SCF stem cell factor, ECP eosinophil cationic protein