SummaryA novel CC chemokine, HCC-1, was isolated from the hemoflhrate of patients with chronic renal failure. HCC-1 has a relative molecular mass of 8,673 and consists of 74 amino acids including four cysteines linked to disulfide bonds. HCC-1 cDNA was cloned from human bone marrow and shown to code for the mature protein plus a putative 19-residue leader sequence. Mature HCC-1 has sequence identity of 46% with macrophage inflammatory protein (MIP)-lc~ and MIP-][3, and 29-37% with the other human CC chemokines. Unlike MIP-I~x and the other CC chemokines, HCC-1 is expressed constitutively in several normal tissues (spleen, liver, skeletal and heart muscle, gut, and bone marrow), and is present at high concentrations (1-80 nM) in plasma. HCC-1 has weak activities on human monocytes and acts via receptors that also recognize MIP-lot. It induced intracellular Ca 2+ changes and enzyme release, but no chemotaxis, at concentrations of 100-1,000 nM, and was inactive on T lymphocytes, neutrophils, and eosinophil leukocytes. In addition, HCC-1 enhanced the proliferation of CD34 + myeloid progenitor ceils. It was as effective as MIP-lci, but about 100-fold less potent.H emofittration is a routine treatment for patients with chronic renal failure to remove substances that are normally cleared by the kidney. A filter membrane with a molecular mass cut-off of 20 kD is used, which virtually excludes plasma proteins (1, 2). Being available in large quantities, the hemoflltrate is an excellent source of biologically active human peptides that circulate in the blood. During the last 5 yr, a peptide bank was established from >200,000 liters of hemofiltrate, and several peptide hormones were purified (1). During the course of a systematic search for novel bioactive factors (3), we have identified a new member of the recently recognized family of chemotactic cytokines (chemokines). HCC-1 is structurally related to macrophage inflammatory protein (MIP)-loc Unlike MIP-lo~ and the other CC chemokines, HCC-1 is highly expressed in normal tissues and is present at high concentrations in human plasma. Materials and MethodsPurification. Peptides were extracted from batches of 2,000 liters of hemofiltrate by precipitation with 660 g/liter ammonium sulfate as described previously (2). The precipitate ("250 g) was dissolved in water (125 mg/ml). The peptides were precipitated again by addition of 4.5 vol of2-propanol, redissolved in 10 mM phosphate buffer, pH 3.0, and fractionated by cation exchange chromatography (Fractogel TSK SP-650 M, 6 • 20 cm; Merck, Darmstadt, Germany) with a 0-1.0-M NaC1 gradient in the same buffer. Fractions eluting at high salt concentrations were collected and further purified by preparative reverse-phase (lkP) HPLC (Parcosil RP C4, 300 ft,, 20-45 b~m, 3 • 12.5 cm; Biotek, Oestringen, Germany) using a gradient generated from 0.01 M HCI and 50% 2-propanol/30% methanol in 0.01 M HCI. Analytical R.P HPLC (Parcosil RP C4, 300 A, 5 btm, 1 • 12.5 cm, Biotek, Oestringen, Germany) was then performed using an acetonitrile/T...

Cloning and sequencing of the upstream region of the gene of the CC chemokine HCC-1 led to the discovery of an adjacent gene coding for a CC chemokine that was named ''HCC-2.'' The two genes are separated by 12-kbp and reside in a head-to-tail orientation on chromosome 17. At variance with the genes for HCC-1 and other human CC chemokines, which have a three-exon-two-intron structure, the HCC-2 gene consists of four exons and three introns. Expression of HCC-2 and HCC-1 as studied by Northern analysis revealed, in addition to the regular, monocistronic mRNAs, a common, bicistronic transcript. In contrast to HCC-1, which is expressed constitutively in numerous human tissues, HCC-2 is expressed only in the gut and the liver. HCC-2 shares significant sequence homology with CK␤8 and the murine chemokines C10, CCF18͞MRP-2, and macrophage inf lammatory protein 1␥, which all contain six instead of four conserved cysteines. The two additional cysteines of HCC-2 form a third disulfide bond, which anchors the COOHterminal domain to the core of the molecule. Highly purified recombinant HCC-2 was tested on neutrophils, eosinophils, monocytes, and lymphocytes and was found to exhibit marked functional similarities to macrophage inf lammatory protein 1␣. It is a potent chemoattractant and inducer of enzyme release in monocytes and a moderately active attractant for eosinophils. Desensitization studies indicate that HCC-2 acts mainly via CC chemokine receptor CCR1.We recently have isolated and characterized a new human CC chemokine, HCC-1 (1), which is structurally similar to macrophage inflammatory protein (MIP)-1␣ (46% amino acid identity) and occurs in high concentrations in human plasma like MIP-1␥ in murine blood. Northern blot analysis revealed that, in contrast to other chemokines, HCC-1 is expressed constitutively at high levels in numerous human tissues. We further showed that HCC-1 interacts with receptors that also recognize MIP-1␣ and RANTES and stimulates the proliferation of CD34 ϩ myeloid progenitor cells in vitro. In the present paper, we report the discovery and characterization of a CC chemokine, HCC-2, that arises from a gene that is arranged in tandem with the gene of HCC-1 on chromosome 17. Mono-as well as bicistronic transcripts of the two genes were detected. Recombinant HCC-2 was expressed and shown to act mainly on monocytes and eosinophils in a similar manner as MIP-1␣. MATERIALS AND METHODSCell Culture. Cell lines (T84, HUH-7) were purchased from the American Type Culture Collection and maintained in DMEM supplemented with 10% fetal calf serum.Oligonucleotides. The oligo-deoxyribonucleotides used were synthesized chemically (Perkin-Elmer) and are listed in Table 1.Gene Cloning and Characterization. A human genomic library in phage (Stratagene) was screened as described (2) by using a partial 269-bp, HCC-1-specific cDNA fragment (1) as a probe. Three independent clones were isolated, and the SstI restriction fragments of one of them were subcloned into pBSK ϩ . Both strands of the HCC-1 and HC...