CCL28 is part of the subfamily of small cytokine CC genes. CCL28 shows chemotactic activity for resting CD4 or CD8 T cells and eosinophils. CCL28 binds to chemokine receptors CCR3 and CCR10. CCL28 is involved in the physiology of extracutaneous epithelial tissues， including diverse mucosal organs. CCL28 mediates mucosal immunity in HIV exposure and infection. CCL28 is involved in the pathogenesis of inflammatory skin diseases.
Human CCL28 cDNA encodes a 127 amino acid residue precursor protein with a putative 22 amino acid residue signal peptide that is cleaved to produce the 105 amino acid residue mature protein. Human and mouse CCL28 are highly conserved， sharing 83% amino acid identity in their mature regions. CCL28 shares the most homology with CCL27/CTACK. Human and mouse CCL28 RNA expression was found to be highest in normal and pathologic colon with the protein being expressed by epithelial cells. Human CCL28 RNA was also present in normal and asthmatic lung tissues.
