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Frequency and clinical significance of myeloid-associated antigen expression in blast cells were assessed in 372 consecutive children with acute lymphoblastic leukemia (ALL). A comprehensive panel of myeloid monoclonal antibodies representing seven cluster groups showed myeloid-associated antigen expression in 61 cases (16.4%), 18 of which expressed two or more antigens. The antigens expressed comprised CD11b (8.9% of the total series), CD13 (6.5%), CD33 (3.2%). CD36 (1.9%), CD15 (1.6%), CD14 (1.3%), and CDw12 (1.1%). No significant associations were found between myeloid-associated antigen expression and the presence of known adverse prognostic features (eg, higher leukocyte count, nonwhite race, older age). Myeloid-associated antigen expression had no effect on remission induction or event-free survival for the 267 children who had been treated with the same combination of chemotherapeutic agents (P= .34). Thus, blast cell expression of myeloid-associated antigens in childhood ALL appears to lack prognostic value in the context of contemporary intensive chemotherapy.

Human macrophage colony-stimulating factor (CSF-1 or M-CSF) is encoded by a single gene that was previously assigned to the long arm of chromosome 5, band q33.1, in a region adjacent to the gene encoding its receptor (Pettenati MJ, et al, Proc Natl Acad Sci USA84:2970, 1987). Using fluorescence in situ hybridization with genomic probes to examine normal metaphase chromosomes, we reassigned the human CSF1gene to the short arm of chromosome 1, bands p13-p21. We confirmed this result by hybridizing a CSF1cDNA probe to filters containing flow-sorted chromosomes and by identifying CSF1sequences in DNAs extracted from human x rodent somatic cell hybrids that contained human chromosome 1 but not human chromosome 5. Our findings are consistent with studies that have shown tight linkage between the murine CSF1 and amylase genes, as part of a conserved linkage group between mouse chromosome 3 and the short arm of human chromosome 1, which also includes the genes encoding the β subunits of thyrotropin and nerve growth factor. Assignment of the CSF1 gene to chromosome 1 at bands p13-p21 raises the possibility that it may be altered by certain nonrandom chromosomal abnormalities arising in human hematopoietic malignancies and solid tumors.© 1991 by The American Society of Hematology. 0006–4971191/7808-0015$3.00/0

Receptors for macrophage colony-stimulating factor (CSF-1R) are expressed not only by monocytes, macrophages, and their progenitors, but also by placental trophoblasts during fetal development. In monocytes, CSF-1Rgene transcripts originate at multiple sites immediately upstream of the gene's coding sequences, whereas in placental cells the transcripts include an additional noncoding exon, located 26 kb upstream near the 3’ end of the B-type platelet-derived growth factor (PDGF)receptor gene. Physically distinct CSF-1Rtranscription origins suggest separate promoter usage by the two cell types. To identify regulatory elements of these promoters, we fused CSF-1Rgenomic sequences to bacterial reporter genes and introduced the resulting constructs into human cell lines and mouse fibroblasts. A 775-bp genomic fragment containing CSF-1R placental transcription origins and adjacent upstream sequences mediated reporter gene expression in BeWo choriocarcinoma cells and mouse NIH-3T3 fibroblasts, but not in myeloid or lymphoid cells. By contrast, a 550-bp genomic fragment containing CSF-1R monocyte transcription origins and 5’ flanking sequences directed gene expression in U-937 human myeloid cells, but not in the other cell types. Thus, nucleotide sequences of fewer than 1,000-bp upstream of the two independent CSF-1R transcription origins contain the minimal promoter elements needed to program appropriate tissue-specific expression of reporter genes.© 1992 by The American Society of Hematology.0006-4971/92/7903-0011S3.00/0

Initial attachment of leukocytes to the vessel wall at sites of inflammation is supported by a family of carbohydrate-binding adhesion molecules called the selectins. Selectin ligands include sialyl-Lewis x (sLex, Neu5Acα2-3Galβ1-4[Fucα1-3]GlcNAc—) and related structures. We report here that defined heparin oligosaccharides interact with the selectins. Heparin chains containing four or more monosaccharide residues inhibited the function of L- and P-selectin, but not E-selectin, in vitro. In a competition enzyme-linked immunosorbent assay measuring inhibition of solution-phase selectin-Ig fusion proteins (selectin-Ig) binding to immobilized bovine serum albumin-sLexneoglycoprotein, a heparin-derived tetrasaccharide mixture inhibited 50% of L- and P-selectin-Ig binding (IC50) at 200 ± 40 µmol/L and 850 ± 110 µmol/L, respectively. A single hexasulfated tetrasaccharide (ΔUA2Sα1-4GlclMS6Sα1-4ldoA2Sα1-4GlcNS6S) was particularly active against L- and P-selectin-Ig (IC50= 46 ± 5 µmol/L and 341 ± 24 µmol/L). By comparison, the tetrasaccharide sLexwas not inhibitory at concentrations up to 1 mmol/L. In cell adhesion assays, heparin tetrasaccharides reduced binding of neutrophils to COS cells expressing P-selectin but not to COS cells expressing E-selectin. They also blocked colon cancer cell adhesion to L- and P-selectin but not E-selectin. In a model of acute inflammation, intravenously administered heparin tetrasaccharides diminished influx of neutrophils into the peritoneal cavities of thioglycollate-treated mice. We conclude that heparin oligosaccharides, including non-anticoagulant tetrasaccharides, are effective L- and P-selectin inhibitors in vitro and have anti-inflammatory activity in vivo.

The first monoclonal antibodies (MoAbs) to epitopes in the extracellular domain of the human c-fmsproto-oncogene product (receptor for the macrophage colony stimulating factor, CSF-1) were used with flow cytometric techniques to study receptor expression on normal human peripheral blood monocytes, bone marrow cells, and leukemic blasts. On normal cells CSF-1 receptors were restricted in their expression to cells of the mononuclear phagocyte lineage. CSF-1 receptors were detected on leukemic blasts from 15 (30%) of 50 children with acute myeloid leukemia, compared with four (15%) of 26 adults. By contrast, detectable CSF-1 receptors were uniformly absent on blasts from 19 children with acute lymphoblastic leukemia. CSF-1 receptors on normal monocytes and myeloid leukemia cells could be induced to downmodulate by incubation with either human recombinant CSF-1 or phorbol esters, confirming that the receptors had functional ligand-binding sites and responded to transmodulation by inducers of protein kinase C. The numbers of receptors per cell and the percentage of positive cases were highest for leukemic blasts with cytochemical and morphological features of monocytes. However, CSF-1 receptors were also detected on a subset of leukemic blast cells with features of granulocytic differentiation (FAB subtypes M1 through M3). Southern blotting analyses of DNA from 47 cases of acute myeloid leukemia demonstrated no rearrangements within the 32 kb of genomic sequences that contain CSF-1 receptor coding exons or in the 50 kb upstream of the first coding exon. Analysis of the upstream region of the c-fms locus revealed that sequences representing the terminal 112 untranslated nucleotides of c-fms mRNA map 26 kb 5’ to the first coding exon, suggesting that at least one c-fms promoter is separated from the receptor coding sequences by a very long intron. Whereas expression of the CSF-1 receptor in myeloid leukemic blasts is not restricted to cells with monocytic characteristics, the apparently aberrant pattern of receptor synthesis in a subset of cases with granulocytic features appears not to be due to chromosomal rearrangements within 50 kb upstream of sequences encoding the receptor.