Acronym for "C-X-C motif chemokine 13". CXCL-13 is a 109 amino acid protein that acts as a chemoattractant (BLC) and a B cell-attracting chemokine 1 (BCA-1). CXCL13 belongs to the "Intercrine alpha family" also called "chemokine CXC". It acts chemotactically for B lymphocytes but not for T lymphocytes, monocytes and neutrophils and binds to BLR1/CXCR5. CXCL-13 labels follicular T cells. CXCL13 is considered a possible biomarker for systemic lupus erythematosus.