Chemokine (C C Motif) Ligand 26 (CCL26) is a novel small cytokine belonging to the CC chemokine family, which involved in immunoregulatory and inflammatory processes. CCL26 is expressed constitutively in thymus, but only transiently in phytohemagglutinin-stimulated peripheral blood mononuclear cells. It specifically binds and induces chemotaxis in T cells and elicits its effects by interacting with the chemokine receptor CCR4. Eotaxin-3/CCL26, along with Eotaxin-1 and Eotaxin-2, selectively activates the CC chemokine receptor 3 (CCR3). The Eotaxin-3-CCR3 interaction may play an important role in allergic diseases such as atopic dermatitis and bronchial asthma. The full-length cDNA for Eotaxin-3 encodes a protein of 94 amino acids with a putative signal peptide of either 23 or 26 amino acid residues. Both the 71 and 68 amino acid residue variants of recombinant Eotaxin-3 demonstrate equal potency in inducing chemotaxis of a human CCR3-transfected cell line. Unlike most other CC chemokines, Eotaxin-3 maps to human chromosome 7q11.2, within 40 kilobases of the Eotaxin-2 loci. Eotaxin-3 and Eotaxin-2 are unique in that they are the only chemokines identified to date that map to chromosome 7.