The Role of Eosinophils and Basophils in the Lung Health and Diseases

Eosinophils and basophils, traditionally recognized for their immune defense functions, have recently been shown to exhibit more complex roles in pulmonary immunity. Emerging evidence indicates that these immune cell populations not only protect the lungs but can also trigger excessive inflammatory responses when dysregulated. The precise roles of eosinophils and basophils in lung homeostasis and disease remain incompletely understood. This chapter comprehensively summarized recent advances in understanding the contributions of eosinophils and basophils in acute lung injury, allergic respiratory diseases (asthma, hypersensitivity pneumonitis), and infection-related pneumonias (bacterial, viral, fungal). We critically analyzed their both protective (immune surveillance and pathogen clearance) and pathogenic (exacerbating inflammation and tissue damage) dual functions with emphasis on cytokine secretions profiles, proinflammation mediators, and granule release mechanisms. Special attention is given to their potential as biomarker for clinical stratification. Translational evidence from murine models and human studies reveals critical knowledge gaps regarding tissue-specific activation thresholds and therapeutic modulation strategies. Furthermore, this chapter highlights promising therapeutic targets within eosinophil and basophil signaling pathways that could facilitate precision medicine approaches for respiratory disorders, ultimately proposing an integrated paradigm that reconciles their dualistic contributions to lung pathophysiology.