Molecular Cloning of Leukotactin-1: A Novel Human β-Chemokine, a Chemoattractant for Neutrophils, Monocytes, and Lymphocytes, and a Potent Agonist at CC Chemokine Receptors 1 and 3

A new member of human β-chemokine cDNA was isolated and named leukotactin-1 (Lkn-1). Lkn-1, along with murine macrophage inflammatory protein-related protein-1 and -2, defines a subgroup of β-chemokines based on two conserved cysteines in addition to the four others conserved in all β-chemokines. The putative mature Lkn-1 is composed of 92 amino acids with a calculated m.w. of 10,162. The Lkn-1 gene was mapped to human chromosome 17, region q12. Recombinant Lkn-1 was a potent chemoattractant for neutrophils, monocytes, and lymphocytes and induced calcium flux in these cells. Lkn-1 specifically induced calcium flux in CCR1- and CCR3-expressing HOS cell lines. Lkn-1 suppressed colony formation by human granulocyte-macrophage, erythroid, and multipotential progenitor cells stimulated by combinations of growth factors. Hence, we have isolated and characterized a human C6 β-chemokine that is a potent agonist at CCR1 and CCR3 and shows broad biologic activities, including leukocyte chemoattraction.