BCA-1/CXCL13 Protein, Human

CXCL13, known as BCA-1 (B cell-attracting chemokine 1) or BLC (B-lymphocyte chemoattractant), is an efficacious attractant selective for B lymphocytes through binding to the BLR1/CXCR5 receptor^[1]. CXCL13 is a homeostatic chemokine, and is constitutively secreted by stromal cells in B-cell areas of secondary lymphoid tissues (follicles), such as spleen, lymph nodes, tonsils, and Peyer's patches^[2]. BCA-1/CXCL13 Protein, Human is produced in E. coli, and consists of 87 amino acids (V23-P109).

CXCL13, also known as B lymphocyte chemoattractant, is originally identified in stromal cells in B cell follicles as regulating homing of B cells and subsets of T cells. CXCL13 plays a key role in orchestrating cell migration within spatially distinct regions of the secondary lymphoid organs. It strongly attracts B lymphocytes while promoting migration of only small numbers of T cells and macrophages. CXCL13 and its receptor, CXCR5, play fundamental roles in inflammatory, infectious, cancer and immune responses^[1][2][3].
The amino acid sequence of human CXCL13 protein has low homology with mouse CXCL13 protein.
CXCL13 exerts its functions through its receptor CXCR5. CXCR5 is highly expressed on mature recirculating B-lymphocytes, a subpopulation of follicular helper T cells (TFH) and skin-derived migratory dendritic cells (DCs), and controls their migration into secondary lymphoid organs towards the gradient of CXCL13. As the loss of the BLR1/CXCR5 receptor is sufficient to disrupt organization of follicles in spleen and Peyer's patches, BCA-1 may act as a B cell homing chemokine. Human BCA-1 competes with radiolabeled IFN-γ inducible protein 10 (IP-10) for binding to the human CXCR3 receptor expressed in Ba/F3 and 293EBNA cell lines. Furthermore, human BCA-1 is an efficacious attractant for human CXCR3 transfected cells. BCA-1 does oes not induce calcium release in B-lymphocytes. In addition, human BCA-1 is an agonist in stimulating GTP gamma S binding. Human BCA-1 is a specific and functional G-protein-linked chemotactic ligand for the human CXCR3 receptor. CXCL13 has been widely implicated in the pathogenesis of a number of autoimmune diseases and inflammatory conditions, as well as in lymphoproliferative disorders. In addition, the CXCL13:CXCR5 axis orchestrates cell-cell interactions that regulate lymphocyte infiltration within the tumor microenvironment^[1][2][3].
Dysregulation of the CXCL13:CXCR5 axis affecting both B- and TFH cell function is major player in autoimmune disorders, and potentially serves as a biomarker for disease progression and therapeutic response. Moreover, expression of CXCR5 and CXCL13 is shown to be dysregulated in HIV infection, such that the number of CXCR5+ B cells decreases with progression of HIV infection, together with an increase in plasma levels of CXCL13. CXCL13/CXCR5 signaling modulates cancer cell ability to grow, proliferate, invade, and metastasize. CXCL13 drives spinal astrocyte activation and neuropathic pain via CXCR5^[1][2][3][4].

Recombinant human CXCL13 (0-15 ng/mL; for 0-6 h) dose dependently induces CXCR5 expression in SAKA-T and MC3T3-E1 cells. Also, CXCL13 (15 ng/mL; 0-60 min) significantly increases p-ERK1/2 in SAKA-T and MC3T3-E1 cells^[5].

1.Full biological activity determined by a chemotaxis bioassay using human B cells is in a concentration range of 1.0-10 ng/mL.
2.Measured in a cell proliferation assay using PC-3 cells. The ED₅₀ for this effect is typically 4.604 ng/mL, corresponding to a specific activity is 2.17×10⁵ units/mg.

• 
  Measured in a cell proliferation assay using PC-3 cells. The ED₅₀ for this effect is typically 4.604 ng/mL, corresponding to a specific activity is 2.17×10⁵ units/mg.

Human

E. coli

Tag Free

O43927 (V23-P109)

10563  [NCBI]

VLEVYYTSLRCRCVQESSVFIPRRFIDRIQILPRGNGCPRKEIIVWKKNKSIVCVDPQAEWIQRMMEVLRKRSSSTLPVPVFKRKIP

Approximately 10.3 kDa

• 
  Greater than 95% as determined by reducing SDS-PAGE.

Lyophilized powder

Lyophilized after extensive dialysis against 20 mM PB, pH 7.4, 100 mM NaCl or PBS, pH 7.4.

<1 EU/μg, determined by LAL method.

It is not recommended to reconstitute to a concentration less than 100 μg/mL in ddH₂O. For long term storage it is recommended to add a carrier protein (0.1% BSA, 5% HSA, 10% FBS or 5% Trehalose).

Stored at -20°C for 2 years. After reconstitution, it is stable at 4°C for 1 week or -20°C for longer (with carrier protein). It is recommended to freeze aliquots at -20°C or -80°C for extended storage.

Room temperature in continental US; may vary elsewhere.

• [1]. Jenh CH, et al. Human B cell-attracting chemokine 1 (BCA-1; CXCL13) is an agonist for the human CXCR3 receptor. Cytokine. 2001 Aug 7;15(3):113-21.  [Content Brief]

  [2]. Muzammal Hussain, et al. CXCL13/CXCR5 signaling axis in cancer. Life Sci. 2019 Jun 15;227:175-186.  [Content Brief]

  [3]. Marcelo G Kazanietz, et al. CXCL13 and Its Receptor CXCR5 in Cancer: Inflammation, Immune Response, and Beyond. Front Endocrinol (Lausanne). 2019 Jul 12;10:471.  [Content Brief]

  [4]. Bao-Chun Jiang, et al. CXCL13 drives spinal astrocyte activation and neuropathic pain via CXCR5. J Clin Invest. 2016 Feb;126(2):745-61.  [Content Brief]

  [5]. Y Sambandam, et al. CXCL13 activation of c-Myc induces RANK ligand expression in stromal/preosteoblast cells in the oral squamous cell carcinoma tumor-bone microenvironment. Oncogene. 2013 Jan 3;32(1):97-105.  [Content Brief]