Minactivin expression in human monocyte and macrophage populations

Adherent monolayer cultures of human blood monocytes, peritoneal macrophages, bone marrow macrophages, and colonic mucosa macrophages were examined for their ability to produce and secrete minactivin, a specific inactivator of urokinase-type plasminogen activator. All except colonic mucosa macrophages produced and secreted appreciable amounts of minactivin, but only blood monocytes were stimulated by muramyl dipeptide (adjuvant peptide) to increase production. The minactivin from each of these populations could be shown to preferentially inhibit urokinase-type plasminogen activator and not trypsin, plasmin, or 'tissue'-type plasminogen activator (HPA66). A plasminogen-activating enzyme present in monocyte cultures appeared unaffected by the presence of minactivin and could be shown to be regulated independently by dexamethasone

Different colon-stimulating factors are detected by the interleukin-3 dependent cell-lines Fdc-Pl and 32D Cl-23

The cell lines FDC-Pl and 32D cl-23 have previously been used as unique indicators for the growth-promoting activity of interleukin-3. We show that FDC-Pl cells respond to granulocyte/macrophage colony-stimulating factor (GM-CSF, CSF-2) as well as to interleukin-3. In keeping with this finding, FDC-Pl cells express the macrophage-specific marker, F4/80. FDC-Pl cells do not, however, respond to macrophage CSF (M-CSF, CSF-1). In contrast, 32D cl-23 cells do not respond to GM-CSF and lack F4/80. Instead, 32D cl-23 cells respond to an as yet undefined factor in conditioned medium (CM) from the primate T cell line, MLA-144, and CM from mitogen-stimulated human lymphocytes (HLCM). 32D cl-23 cells are Lyt-1. Both FDC-Pl and 32D cl-23 cells consume interleukin-3, but only FDC Pl cells consume GM-CSF. Similarly, 32D cl-23, but not FDC-Pl, cells consume 32D cl-23 growth factor from MLA-144 CM and HLCM. Interleukin-3-dependent cell lines must therefore concurrently express different functional cell surface receptors for a variety of biochemically distinct growth factors

Cloning and expression of the rat interleukin-3 gene.

Genomic clones carrying the rat interleukin-3 (IL-3) gene have been isolated and the nucleotide sequence of the gene determined. Alignment of this sequence with that of the mouse IL-3 gene has allowed the structure of the rat IL-3 gene to be deduced. The intron-exon boundaries are conserved and extensive nucleotide homology (approx 90%) is present in the 5' flanking region and the portion of the gene coding for the signal peptide. Several proposed regulatory sequences are conserved and an analogous element to the tandem repeat in intron 2 of the mouse gene is also present. The predicted amino acid sequence for mature rat IL-3 shows surprisingly low homology (54%) with its murine counterpart, although all four cysteine residues are conserved. The rat IL-3 gene was expressed in monkey COS-1 cells and colony assays established that rat IL-3 is a multi-lineage haemopoietic growth regulator. There was little cross-reactivity of the respective IL-3 species on mouse and rat bone marrow cells suggesting that rat IL-3, in concert with its receptor, has evolved significantly away from the mouse IL-3/receptor system