CC chemokine receptor (CCR) 5 and
CXC chemokine receptor (CXCR)3 are expressed on T helper cell type 1 cells and have been implicated in their migration to sites of
inflammation. Our preceding study demonstrated that a nonpeptide synthetic CCR5 antagonist,
TAK-779 (N, N-dimethyl-N-[4-[[[2-(4-methylphenyl)-6, 7-dihydro-5H-benzocyclohepten-8-yl]
carbon-yl]amino]benzyl]-tetrahydro-2H-pyran4-aminium
chloride, inhibits the development of experimentally induced
arthritis by modulating the migration of CCR5(+)/CXCR3(+) T cells to joints. The present study investigated the functional properties of
TAK-779, including the effect of this antagonist on CXCR3 function. For this purpose, transfectants expressing mouse CCR5 (mCCR5) or mCXCR3 and expressing mCCR4 or mCXCR4 as controls were established by introducing each relevant gene into 2B4 T cells and were subjected to the following assays. First, the
ligand binding to
chemokine receptors was assayed by incubating transfectants with [(125)I]-labeled relevant
ligand or with the unlabeled relevant
ligand followed by staining with anti-
ligand antibody. Second,
chemokine-induced
lymphocyte function-associated antigen-1 (LFA-1) activation was assayed by measuring the adhesion of cells to microculture plates coated with purified
intercellular adhesion molecule-1. Third,
chemokine-stimulated chemotaxis was assayed by observing the cell migration through transwells. In these assays,
TAK-779 blocked the
ligand binding as well as LFA-1 up-regulating and chemotactic function of mCXCR3 and mCCR5 but did not elicit a biologically significant inhibition of those functions of mCCR4 and mCXCR4. These observations indicate the unique target specificity of
TAK-779 and explain why this antagonist efficiently blocks the migration of T cells expressing CCR5 and CXCR3 to sites of
inflammation.