• Purity

  >97%, by SDS-PAGE under reducing conditions and visualized by silver stain

• Endotoxin Level

  <0.01 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured by its ability to chemoattract 5-10 day cultured human peripheral blood lymphocytes (PBL). The ED    ₅₀ for this effect is 50-200 ng/mL. Measured by its ability to chemoattract BaF3 mouse pro‑B cells transfected with human CCR7. The ED    ₅₀ for this effect is 3-15 ng/mL.

• Source

  E. coli-derived Ser24-Gly133

• Accession #

• N-terminal Sequence    
  Analysis

  Ser24

• Predicted Molecular Mass

  12 kDa

• SDS-PAGE

  16-17 kDa, reducing conditions

Carrier Free

What does CF mean?

CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our recombinant proteins. Adding a carrier protein enhances protein stability, increases shelf-life, and allows the recombinant protein to be stored at a more dilute concentration. The carrier free version does not contain BSA.

What formulation is right for me?

In general, we advise purchasing the recombinant protein with BSA for use in cell or tissue culture, or as an ELISA standard. In contrast, the carrier free protein is recommended for applications, in which the presence of BSA could interfere.

Background: CCL21/6Ckine

CCL21, also known as 6Ckine, TCA-4, SLC, Exodus-2, and A21, is a 12 kDa homeostatic chemokine that plays an important role in adaptive immune responses and inflammation (1). Unlike other CC chemokines, mouse CCL21 has a 36 amino acid (aa) C-terminal extension which mediates its attachment to carbohydrate structures and extracellular matrix components (2, 3). Mature mouse CCL21 shares 71% and 84% aa sequence identity with human and rat CCL21, respectively (4‑6). In mouse, three genes encode CCL21, with B and C forms being identical and the A form carrying serine at aa 65 instead of leucine. Both human and mouse CCL21 signal through the chemokine receptor CCR7, while mouse CCL21 additionally can signal through CXCR3 (7). CCL21 is constitutively presented on initial lymphatic vessels, high endothelial venules (HEV), and lymph node dendritic cells (DC) (8‑10). Immobilized CCL21 promotes the docking of DC to lymphatic vessels and the retention of T cells by lymph node DC, resulting in T cell priming for activation (8, 9). DC interaction with the anchored chemokine can induce CCL21 cleavage and release of an 8 kDa fragment that lacks the C‑terminal extension (10). During chronic inflammation or tissue damage, CCL21 is up‑regulated on local vascular endothelial cells, macrophages, T cells, and neurons (11‑14). In these settings, it promotes fibrosis, inflammatory cytokine production, and neuropathic pain (12‑14). The soluble chemokine is elevated in rheumatoid arthritis synovial fluid and in the serum of coronary artery disease patients (11, 13). CCL21 has been shown to exert either angiogenic or angiostatic effects (11, 15, 16). These effects, in combination with the ability of CCL21 to attract immune suppressor cells (Treg and MDSC) to a tumor site can have positive or negative effects on tumor progression (16, 17).

• References:

1. Forster, R. et al. (2008) Nat. Rev. Immunol. 8:362.

2. Yang, B.G. et al. (2007) J. Immunol. 179:4376.

3. Rey-Gallardo, A. et al. (2010) Glycobiology 20:1139.

4. Tanabe, S. et al. (1997) J. Immunol. 159:5671.

5. Hromas, R. et al. (1997) J. Immunol. 159:2554.

6. Hedrick, J.A. and A. Zlotnik (1997) J. Immunol. 159:1589.

7. Jenh, C. et al. (1999) J. Immunol. 162:3765.

8. Tal, O. et al. (2011) J. Exp. Med. 208:2141.

9. Friedman, R.S. et al. (2006) Nat. Immunol. 7:1101.

10. Schumann, K. et al. (2010) Immunity 32:703.

11. Pickens, S.R. et al. (2012) Arthritis Rheum. 64:2471.

12. Sakai, N. et al. (2006) Proc. Natl. Acad. Sci. USA 103:14098.

13. Damas, J.K. et al. (2007) Arterioscler. Thromb. Vasc. Biol. 27:614.

14. Biber, K. et al. (2011) EMBO J. 30:1864.

15. Soto, H. et al. (1998) Proc. Natl. Acad. Sci. USA 95:8205.

16. Vicari, A.P. et al. (2000) J. Immunol. 165:1992.

17. Shields, J.D. et al. (2010) Science 328:749.

• Entrez Gene IDs:

  6366 (Human); 18829 (Mouse); 298006 (Rat)

• Alternate Names:

  6Ckine; 6CkineSmall-inducible cytokine A21; Beta-chemokine exodus-2; CCL21; chemokine (C-C motif) ligand 21; CKb9; exodus-2; member 21; SCYA21; SCYA21MGC34555; secondary lymphoid tissue chemokine; SLC; SLCSecondary lymphoid-tissue chemokine; TCA-4