BCA-1/BLC, a CXC chemokine, is expressed in the liver, spleen, lymph nodes, appendix and stomach. It exerts its activities through its only receptor CXCR5. BCA-1/BLC is a potent chemoattractant for B lymphocytes and induces weak chemotactic response in T cells and macrophages. It manifests no activity on neutrophils and monocytes. Recombinant murine BLC is a 9.8 kDa protein containing 88 amino acid residues including the four highly conserved cysteine residues present in CXC chemokines.