Eotaxin, also named MPIF-2 and Ck beta 6, is a novel CC chemokine identified in the Human Genome Sciences, Inc. database based on the presence of the CC motif and homology with other known CC chemokines. Eotaxin-2 cDNA encodes a 119 amino acid residue precursor protein with a 26 aa residue signal peptide that is cleaved to generate a mature protein predicted to contain 93 amino acid residues with an N-glycosylation site. Although one recombinant preparation of MPIF‑2/Eotaxin-2 from insect cells was reported to be glycosylated and of the predicted size (10.5 kDa), a second preparation of recombinant Eotaxin-2 prepared by a different group, also from insect cells, was shown to contain a 78 amino acid residue carboxy-terminally truncated variant of Eotaxin-2. Additional minor carboxy-terminally truncated variants with 73, 75 and 76 residues were also isolated. Compared to other CC chemokines, Eotaxin-2 exhibits 40%, 42%, and 39% amino acid identity to MCP-3, MIP-1 alpha, and Eotaxin, respectively. Eotaxin-2 mRNA is weakly expressed in activated monocytes and T lymphocytes.
Recombinant Eotaxin-2 has been shown to induce chemotaxis of eosinophils, basophils, and resting T lymphocytes but not monocytes and activated T lymphocytes. Eotaxin-2 has also been shown to suppress the colony formation by the high proliferative potential colony-forming cells which represent multipotential hematopoietic progenitors. On eosinophils, the effects of Eotaxin-2 was shown to be inhibited by an anti-CCR-3 antibody and to be cross-desensitized by Eotaxin or MCP-4, suggesting that all three CC chemokines act through CCR3, at least on eosinophils.
