CSF2 (colony-stimulating factor 2, also known as GM-CSF) is a cytokine that stimulates growth and differentiation of hematopoietic precursor cells across multiple lineages, including granulocytes, macrophages, eosinophils, and erythrocytes. The protein functions through JAK-STAT signaling pathways to promote myeloid cell differentiation and dendritic cell development 1. CSF2 plays critical roles in immune regulation and pathology. In autoimmune contexts, NKp46+ innate lymphoid cells produce CSF2 to promote monocyte-derived macrophage expansion, amplifying tissue damage in lupus nephritis 2. Similarly, pathogenic T-helper 17.1 cells produce CSF2 in immune checkpoint inhibitor-related pneumonitis, establishing a feedforward loop with pro-inflammatory monocytes that drives autoimmune lung inflammation 3. In cancer, CSF2 facilitates macrophage-derived CXCL8 secretion in gastric cancer, contributing to immunosuppressive tumor microenvironments 4. Conversely, CSF2 elevation can promote beneficial M1 macrophage polarization in colorectal cancer treatment responses 5. CSF2 is also required for human M cell development in intestinal immune tolerance 1. Dysregulation of CSF2 signaling appears central to both autoimmune pathology amplification and tumor immune evasion, making it a significant therapeutic target.