CSF2 and neoplasm: Among these, interleukin-5 (IL-5) plays a central role in eosinophilopoiesis by promoting differentiation, survival, and activation of eosinophils.[9,10] Elevated IL-5 levels have been documented in lung carcinoma and correlate with eosinophil counts, decreasing only after tumor resection.[11] GM-CSF and IL-2 may further amplify this effect[12,13], as demonstrated by their presence in pleural fluid of affected patients.[12]