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J. Exp. Med.,
Volume 187, Number 12, June 15, 1998 2009-2021
By


From the * Department of Molecular Sciences and the Chemokines are essential mediators of normal leukocyte trafficking as well as of leukocyte recruitment during inflammation. We describe here a novel non-ELR CXC chemokine identified through sequence analysis of cDNAs derived from cytokine-activated primary human astrocytes. This novel chemokine, referred to as I-TAC (interferon-inducible T cell alpha
chemoattractant), is regulated by interferon (IFN) and has potent chemoattractant activity for
interleukin (IL)-2-activated T cells, but not for freshly isolated unstimulated T cells, neutrophils, or monocytes. I-TAC interacts selectively with CXCR3, which is the receptor for two
other IFN-inducible chemokines, the IFN-
Department of Immunology, Central Research
Division, Pfizer Inc., Groton, Connecticut 06340; and the § Theodor Kocher Institute, University of
Bern, CH-300-ern-9, Switzerland
-inducible 10-kD protein (IP-10) and IFN-
-
induced human monokine (HuMig), but with a significantly higher affinity. In addition, higher potency and efficacy of I-TAC over IP-10 and HuMig is demonstrated by transient mobilization of intracellular calcium as well as chemotactic migration in both activated T cells and
transfected cell lines expressing CXCR3. Stimulation of astrocytes with IFN-
and IL-1 together results in an ~400,000-fold increase in I-TAC mRNA expression, whereas stimulating
monocytes with either of the cytokines alone or in combination results in only a 100-fold increase in the level of I-TAC transcript. Moderate expression is also observed in pancreas, lung,
thymus, and spleen. The high level of expression in IFN- and IL-1-stimulated astrocytes suggests that I-TAC could be a major chemoattractant for effector T cells involved in the pathophysiology of neuroinflammatory disorders, although I-TAC may also play a role in the migration of activated T cells during IFN-dominated immune responses.
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