CXCL13

CXCL13, also known as B-lymphocyte chemoattractant (BLC) or B cell–activating chemokine 1 (BCA-1), is a secreted chemokine of the CXC family. It binds the chemokine receptor CXCR5 and plays a central role in directing B cells to the follicles of secondary lymphoid organs.

Expression of CXCL13 is greatest in tissues involved in immune responses. It is produced predominantly by follicular dendritic cells within lymphoid organs such as lymph nodes and the spleen, as well as by various stromal cells. Some T helper cells, including follicular helper T cells, can produce CXCL13 under certain conditions.

Biologically, the CXCL13–CXCR5 axis guides the migration of B cells into B cell follicles and supports the formation and maintenance of germinal centers. This axis contributes to the organization of lymphoid tissue architecture and facilitates interactions between B cells and T cells during adaptive immune responses.

Clinical significance of CXCL13 emerges from its association with disease activity and its potential as a biomarker. Elevated CXCL13 levels have been observed in autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus, reflecting active follicular responses. In the nervous system, CXCL13 can be detected in cerebrospinal fluid in certain inflammatory or neoplastic conditions and is studied as a biomarker for disorders such as primary CNS lymphoma and neurosarcoidosis. Therapeutically, targeting the CXCL13–CXCR5 axis is explored as a means to modulate B cell localization and germinal center activity in autoimmune disease and B cell–related malignancies.