Characterization of CKβ8 and CKβ8-1: Two alternatively spliced forms of human β-chemokine, chemoattractants for neutrophils, monocytes, and lymphocytes, and potent agonists at CC chemokine receptor 1

Two new members of human β-chemokine cDNA were isolated based on structural and functional similarities to human leukotactin-1. One of these clones was identical to the previously isolated human β-chemokine, CKβ8, whereas the other is a splicing variant of CKβ8, therefore named CKβ8-1. CKβ8 was short in 51 nucleotides (17 amino acids) compared with CKβ8-1. The mature proteins of CKβ8-1 and CKβ8 consisted of 116 and 99 amino acids with calculated molecular weights of 12,500 and 10,950, respectively. Both CKβ8- 1 and CKβ8 were potent agonists at CCR1. These chemokines chemoattracted neutrophils, monocytes, and lymphocytes. They also significantly suppressed colony formation by human bone marrow, granulocyte-macrophage, erythroid, and multipotential progenitor cells stimulated by combinations of growth factors. To our knowledge, this is the first example that an alternative splicing produces two active β-chemokines from a single gene.