Blood, 15 April 2001, Vol. 97, No. 8, pp. 2193-2193
If it's Tuesday, this must be a Belgian chemokine
In 1969, a forgettable Hollywood movie parodied the information
overload that tourists experience when they visit several countries in
the shortest time possible. Thirty years later, scientists who are
interested in chemokines also find their heads spinning in response to
a seemingly endless and rapid parade of newly discovered chemokines and
receptors. In this issue, Struyf and colleagues (page 2197) introduce
us to the newest member of this family of proteins, which they call
Regakine-1 in honor of the Rega Institute of Leuven, Belgium, where the
discovery occurred.
Chemokines are best known for their ability to attract specific
leukocyte subsets, and like with any chemotactic factor, directionality is dictated by establishing a chemokine concentration gradient. Thus it
is one of the particularly galling puzzles of chemokine biology that a
small number of these proteins circulate at high concentrations in
plasma. Regakine-1 is one of these. Struyf and colleagues purified it
from bovine serum, and like another circulating chemokine, HCC-1
(CCL14), Regakine-1 is present at 100-300 ng/mL in bovine serum. It is
a weak chemoattractant for neutrophils and T lymphocytes, but given its
high ambient concentration, its role as a primary attractant for these
cells seems unlikely. Instead, Struyf and colleagues show that it
enhances chemotactic responses to suboptimal doses of more potent
chemokines and other attractants. It may be that Regakine-1 circulates
in order to enhance migratory responses of blood-borne leukocytes. Why
nature would choose this route rather than simply enhancing the
inherent efficacy of chemokine receptor signal transduction is a
mystery (if, in fact, this is Regakine-1's function). Solving the
conundrum posed by Regakine-1's high plasma concentration will be a
fascinating problem and is likely to reveal unexpected opportunities
for influencing leukocyte migration in health and disease. Meanwhile,
like gawkers on a whirlwind tour, we must do our best to keep up with
the changing scenery.
Barrett J. Rollins
Dana-Farber Cancer Institute and Brigham and Women's
Hospital
