CXCL9 (C-X-C motif chemokine ligand 9) is a key immune-regulatory chemokine that primarily functions in T cell recruitment and activation through binding to the CXCR3 receptor 1. The protein is strongly induced by interferon-gamma (IFN-γ) and plays a central role in Th1-type immune responses, correlating with tissue infiltration of T cells 1. CXCL9 acts as a chemoattractant for activated T cells, particularly CXCR3+CD8+ T cells, and is involved in autoimmune processes such as vitiligo where it promotes melanocyte destruction through recruitment of cytotoxic T cells 2. In the tumor microenvironment, CXCL9 influences tumor-associated macrophage polarity and serves as a prognostic indicator, with its expression affecting treatment responses and patient outcomes 3. The chemokine demonstrates therapeutic potential in cancer immunotherapy, where CXCL9-engineered dendritic cells enhance T cell infiltration and activation, improving immune checkpoint blockade efficacy in non-small cell lung cancer 4. CXCL9 also serves as a diagnostic biomarker for acute interstitial nephritis, with significantly elevated urinary levels in affected patients 5. Additionally, CXCL9 plays roles in vascular remodeling, neuroinflammation, and formation of tertiary lymphoid structures that predict immunotherapy responses 67.