XCL1 (chemokine (C motif) ligand 1), also known as lymphotactin, is a unique chemokine that plays a critical role in immune regulation. Unlike most chemokines, XCL1 exists in two distinct conformations due to a dynamic interconversion between a conserved chemokine fold and an unstructured monomer, enabling dual functions in immune cell recruitment and activation. It is primarily produced by natural killer (NK) cells, CD8+ T cells, and γδ T cells during viral infections, inflammatory responses, or tumor surveillance. XCL1 binds specifically to its receptor XCR1. which is selectively expressed on cross-presenting dendritic cells (cDC1), a subset critical for antigen cross-presentation and cytotoxic T-cell priming. This XCL1-XCR1 axis facilitates targeted communication between effector lymphocytes and dendritic cells, enhancing anti-tumor immunity and antiviral responses.
Antibodies targeting XCL1 are valuable tools for studying this pathway. They are used to block or detect XCL1 in experimental models to elucidate its role in immune dynamics, tumor microenvironments, or autoimmune diseases. Therapeutic applications are also explored, as modulating XCL1 activity could enhance dendritic cell recruitment in cancer immunotherapy or suppress pathological inflammation. Monoclonal XCL1 antibodies, often validated for specificity in ELISA, flow cytometry, or neutralization assays, have contributed to understanding tissue-specific immune responses and refining immunotherapeutic strategies. Challenges remain in balancing XCL1's dual structural states for clinical translation, but its unique biology continues to drive research interest.