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From the * Theodor Kocher Institute, University of Bern, CH-3000 Bern, Switzerland; A novel human CC chemokine consisting of 78 amino acids and having a molecular mass of
8,778.3 daltons (VVIPSPCCMF FVSKRIPENR VVSYQLSSRS TCLKAGVIFT TKKGQQ
SCGD PKQEWVQRYM KNLDAKQKKA SPRARAVA) was isolated together with three
minor COOH-terminally truncated variants with 73, 75, and 76 residues. The new chemokine
was termed eotaxin-2 because it is functionally very similar to eotaxin. In terms of structure,
however, eotaxin and eotaxin-2 are rather distant, they share only 39% identical amino acids
and differ almost completely in the NH2-terminal region. Eotaxin-2 induced chemotaxis of
eosinophils as well as basophils, with a typically bimodal concentration dependence, and the release of histamine and leukotriene C4 from basophils that had been primed with IL-3. In all assays, eotaxin-2 had the same efficacy as eotaxin, but was somewhat less potent. The migration
and the release responses were abrogated in the presence of a monoclonal antibody that selectively blocks the eotaxin receptor, CCR3, indicating that eotaxin-2, like eotaxin, acts exclusively via CCR3. Receptor usage was also studied in desensitization experiments by measuring
[Ca2+]i changes in eosinophils. Complete cross-desensitization was observed between eotaxin-2,
eotaxin and MCP-4 confirming activation via CCR3. No Ca2+ mobilization was obtained in
neutrophils, monocytes and lymphocytes, in agreement with the lack of chemotactic responsiveness. Intradermal injection of eotaxin-2 in a rhesus monkey (100 or 1,000 pmol per site) induced a marked local infiltration of eosinophils, which was most pronounced in the vicinity of
postcapillary venules and was comparable to the effect of eotaxin.
Division of
Rheumatology, University Hospital, CH-3010 Bern, Switzerland; § Institute of Immunology and
Allergology, University Hospital, CH-3010 Bern, Switzerland; and
Hoffmann-La Roche Ltd.,
Basel, Switzerland
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