The individual and unique roles for eosinophils and interleukin-5 in the innate immune response to sepsis

Sepsis is a life‑threatening inflammatory response to infection and remains a major clinical challenge. Although sepsis causes widespread immune dysfunction and eosinopenia, recent evidence links higher IL‑5 levels with improved patient survival. This work clarifies the roles of eosinophils and IL‑5 in sepsis. Eosinophils show direct antibacterial activity through granule‑mediated killing, improving bacterial clearance in vivo. IL‑5 also provides protection independent of eosinophils, enhancing survival, promoting neutrophil recruitment, and activating macrophages through increased cytokine production, phagocytosis, and STAT‑1 signaling. These findings reveal IL‑5 and eosinophil granules as potential therapeutic strategies and suggest caution when using anti‑IL‑5–based treatments in septic patients.