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Leukaemic cells from a patient in the blast crisis of chronic myeloid leukaemia were subjected to a surface marker analysis using a panel of monoclonal antibodies recognizing differentiation antigens of myeloid (MY7, MY906, VIM D5, M phi P9), erythroid (VIE G4), megakaryocyte (AN51), T-lymphoid (WT1, 10.2, OKT3, OKT4, OKT6, OKT8, OKT11A) and B-lymphoid cells (B1, B2, Y29/55), common ALL-antigen (VILA1), non-lineage-restricted antigens (OKT9, OKT10), monomorphic HLA-DR determinants (7.2) as well as TdT. When the patient entered his first blast crisis, his blasts expressed a phenotype corresponding to an immature myeloid cell (7.2+, MY7+, My906+, VIM D5-). Ph1-chromosome-positive blasts from this patient's first relapse had completely changed their surface marker characteristics: they had become TdT-positive and exhibited surface features characteristic of early T blasts (WT1+, 10.2+, OKT9+, OKT10+, 7.2-, OKT6-). Together, these features provide evidence that myeloid cells may share a common precursor with T cells.

Human vascular endothelial cells (HUVECs), which do not display the lipopolysaccharide (LPS) receptor CD14, were examined for protein tyrosine phosphorylation after LPS stimulation in the presence and absence of soluble CD14 (sCD14). By phosphotyrosine Western blotting and immunocomplex kinase assays we show that LPS was capable of inducing in these cells rapid protein tyrosine phosphorylation and kinase activation of two members of the mitogen-activated protein kinase (MAPK) family erk-1 and the newly discovered p38, requiring the presence of sCD14. LPS-induced tyrosine phosphorylation of MAPK was associated with increased transcript- and surface protein expression of intracellular adhesion molecule-1 by HUVECs. MAPK phosphorylation and activation was induced by LPS in concentrations as little as 30 ng/mL and as early as 15 minutes after stimulation. Furthermore, tyrosine kinase inhibitors such as Genistein partially inhibited this effect. These results show that LPS triggers similar signaling events in both CD14+ myelo-monocytic cells and cells lacking the putative LPS-receptor CD14, suggesting the presence of a common, yet unidentified element in LPS-signaling in both cell types.

The CD30 surface molecule is a recently identified member of the tumor necrosis factor/nerve growth factor receptor superfamily. Within the cytoplasmic signal transducing domain, CD30 shares no significant homology to other members of this family. Signaling events engaged via CD30 are still unknown. We here identify the NF-kappabeta transcription factor as a target of the CD30-induced signal pathway in Hodgkin's disease (HD) cells. Exposure of HD cells to CD30 ligand induces release of interleukin-6 (IL-6) that can be duplicated by cross-linking HD- cells to an agonistic anti-CD30 specific monoclonal antibody (alphaCD30), but not by cross-linking to an isotype-identical irrelevant monoclonal antibody. Cross-linking of HD cells to alphaCD30 leads to enhanced accumulation of IL-6 mRNA in a time-dependent fashion resulting from transcriptional activation of the IL-6 promoter. Transient transfection assays using a series of deleted IL-6 promoter constructs linked to the human growth hormone gene as a reporter gene furthermore indicate that transcriptional activation of the IL-6 promoter requires the presence of an intact NF-kappabeta binding site. In addition, introduction of an NF-kappabeta binding site appeared to be sufficient to confer inducibility of an heterologous promoter on activation of CD30 in HD cells. Cross-linking of CD30 promotes rapid and transient binding activity of nuclear proteins to the NF-kappabeta recognition site of the IL-6 promoter. Supershift experiments using a series of monoclonal antibodies recognizing distinct members of the NF- kappaBeta transcription factor family furthermore indicate that in CD30 cross-linked HD cells p50, p65/Rel-A, and Rel-B are present, whereas the c-rel protein is not.

Expression of the interleukin-2 receptor alpha-(IL-2Ralpha-), IL-2Rbeta- , and the recently identified IL-2Rgamma-chain was examined on a wide range of cells of myeloid origin including neutrophils, monocytes, normal bone marrow-derived myeloid progenitors enriched for CD34+ cells, bone marrow blasts obtained from acute myelogenous leukemia (AML) patients, and permanent myeloid leukemia cell lines by reverse transcriptase-polymerase chain reaction and surface membrane analysis using receptor chain-specific monoclonal antibodies and flow cytometry. Expression of the p75 IL-2Rbeta- and the p64 IL-2Rgamma-chain was a common finding in most of the myeloid cell samples investigated, whereas IL-2Ralpha-chain was less frequently expressed. Although the high-affinity IL-2R form (ie, the alpha+, beta+, gamma+ IL-2R form) was detectable in a small minority of primary AML samples as well as the KG- 1 cell line and IL-2 binding to these cells was sufficient to initiate signal transduction as evidenced by an increase in overall protein tyrosine phosphorylation and more specifically in tyrosine phosphorylation of the Janus kinase (JAK) 3, in none of these cell types did exposure to IL-2 affect cell growth kinetics. These results suggest that, in myeloid cells, the IL-2R may not stimulate mitogenic responses or that its components may be expressed in a combinational association with receptors for other cytokines and that IL-2Rgamma may play a regulatory role in normal and malignant myelopoiesis possibly independent from IL-2. Because recent studies by others have indicated that the IL-2Rgamma- chain may be shared by the IL-4R, the IL-7R, and most likely the IL-9R, expression of mRNA of these receptor types was also investigated in these cell samples. Surprisingly, in a substantial part of the myeloid lineage cells examined, an IL-2Rgamma+, IL-4R-, IL7R- configuration was noted that was, however, frequently associated with expression of IL-9R. Sharing of IL-9R/IL-2R components was furthermore suggested by inhibition of 125I-IL-2 binding to primary AML cells with excess of unlabeled IL-9.

Mononuclear cells (MNCs) containing peripheral blood stem cells (PBSCs) were obtained from solid-tumor patients undergoing mobilizing chemotherapy followed by granulocyte colony-stimulating factor for PBSC transplantation-supported dose-intensified anticancer chemotherapy and were transplanted into unconditioned “nonleaky” young severe combined immunodeficient mice. Multilineage engraftment was shown by flow cytometry and immunocytochemistry using monoclonal antibodies to various human cell surface antigens as well as identification of human immunoglobulin in murine sera. Within a dose range of MNCs suitable for transplantation (10 to 36 x 10(6) cells/graft) the number of CD34+ cells injected (optimal at > 0.7 x 10(6)/graft) determined the yield of human cells produced in recipient animals. Engraftment of hu PBSC preparations resulted in prolonged generation of physiologic levels of human cytokines including interleukin-3 (IL-3), IL-6, and granulocyte- macrophage colony-stimulating factor, which were detectable in the murine blood over a period of at least 4 months. In vivo survival of immature human progenitor cells was preserved even 9 months after transplantation. Because human IL-3 is known to stimulate early hematopoiesis, a rat fibroblast cell line was stably transfected with a retroviral vector carrying the human IL-3 gene and cotransplanted subcutaneously as additional source of growth factor. Cotransplants of this cell line producing sustained in vivo levels of circulating human IL-3 for at least 12 weeks significantly accelerated the process of engraftment of huPBSC and spurred the spread of mature human cells to the murine spleen, liver, thymus, and peripheral blood. Cotransplants of allogeneic human bone marrow stromal cells derived from long-term cultures resulted in a comparable--though less prominent--support of engraftment.

Interleukin 5 (IL-5) is a T-cell lymphokine known to stimulate development, functional activity, and in vitro survival of eosinophils. Tissue and blood eosinophilia occurring during allergic responses of the immune system are potentially mediated by IL-5 secreting T-cells. To test this hypothesis a series of allergen-specific T-cell clones were established from peripheral blood and skin lymphocytes of patients with atopic dermatitis and house dust mite sensitization. In addition, alloreactive T-cell clones were also prepared from peripheral blood lymphocytes of healthy donors. Cloned T-cells were analyzed for IL-5 mRNA expression and IL-5 secretion by means of in vitro gene amplification using the reverse transcriptase polymerase chain reaction and IL-5 specific oligonucleotide hybridization, as well as IL-5-specific ELISA. A majority of allergen-specific long-term cultured T-cell clones (84%) of different donors and of either phenotype (CD8+ or CD4+) disclosed IL-5 transcripts on stimulation with lectins. Almost all clones exhibiting IL-5 transcripts also released immunoreactive IL-5 protein into their culture supernatants. In contrast, only 2% of alloreactive T-cell clones obtained from healthy donors and none of alloreactive T-cell clones of one atopic patient investigated expressed detectable amounts of IL-5 mRNA in response to lectin stimulation, all of whom were CD4+. These results suggest that eosinophilia observed in allergic responses in the peripheral blood and in tissues at the site of induced late-phase cutaneous reaction may be associated with IL-5 release by allergen-specific T-cells.

Transforming growth factor-beta (TGF-beta) is a potent inhibitor of growth factor-stimulated hematopoiesis in normal and leukemic conditions. Using the factor-dependent myelogenous leukemia cell lines GF-D8 and Mo7, we show that TGF-beta interferes with stem cell factor (SCF)-induced proliferation by downmodulating c-jun gene expression. The ability of SCF to induce accumulation of c-jun transcripts was abolished when TGF-beta was present in culture. Transcriptional nuclear run-on assays indicated that TGF-beta relieved the capacity of SCF to enhance the transcriptional rate of the c-jun gene. Deletion analysis of the c-jun promoter furthermore showed that SCF was activating the c- jun promoter via the NF-jun transcription factor. Gel mobility shift assays showed that SCF increased the binding activity of NF-jun to its recognition site within 5 to 15 minutes. Binding activity peaked at 1 hour after exposure to SCF and declined to starting levels within 4 hours. The ability of SCF to enhance NF-jun binding activity was also dose-dependent in the range of 5 to 100 ng/mL. Exposure of GF-D8 and Mo7 cells to TGF-beta before the addition of SCF antagonized SCF- induced NF-jun binding. Moreover, whereas SCF was capable of functionally activating a heterologous promoter containing the NF-jun binding site, pretreatment of GF-D8 cells with TGF-beta abolished transcriptional activation of this heterologous promoter. These findings indicate that SCF-mediated activation of c-jun via NF-jun is crucial for the SCF-inducible proliferative response and is inhibited by TGF-beta. In additional experiments, the antisense technique was used. Treatment of GF-D8 and Mo7 cells with an antisense oligodeoxyribonucleotide directed against the translation initiation site of c-jun abolished the capacity of SCF to induce a proliferative response, whereas sense and nonsense oligomers had no effect. Taken together, our data indicate that the counteracting modulation of the binding activity of NF-jun by SCF and TGF-beta regulates the expression of the c-jun gene and thereby the proliferative state of the GF-D8 and Mo7 target.

Interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) have previously been reported to induce rapid phosphorylation of the mitogen-activated protein (MAP) kinase. However, little is known about signaling events initiated by both hematopoietins that occur downstream of the MAP kinase. MAP kinase has been shown to phosphorylate the AP-1 transcription factor and also to activate two kinases designated insulin-stimulated protein kinase-1 and MAP kinase- activated protein (MAP-KAP) kinase 2. We show here that IL-3 and GM-CSF induce MAPKAP kinase 2 activity in the human megakaryoblastic leukemia cell line MO7 and phosphorylate the human small heat shock protein Hsp 27 on serine residues in vitro. GM-CSF also induced Hsp 27 phosphorylation in neutrophils in a range similar to that observed in MO7 cells, suggesting that MAPKAP kinase 2-mediated Hsp 27 activation occurs independently of proliferation. Hsp 27 phosphorylation was dose- dependent, occurred as early as 5 minutes after factor exposure, and was inhibited by the tyrosine kinase inhibitors genistein and herbimycin A. Furthermore, the protein phosphatase A2 abolished IL-3- and GM-CSF-induced serine phosphorylation of Hsp 27. Taken together, our findings indicate that tyrosine phosphorylation of MAP kinase is a prerequisite for serine phosphorylation of Hsp 27, which is mediated by MAPKAP kinase 2. Hsp 27 has shown activation-dependent translocation from the cytosolic to the nuclear region and has been linked to the cellular stress response. However, its precise function is largely unknown. Our data identify Hsp 27 as a target of the IL-3/GM-CSF stimulation pathway that involves MAP kinase and MAPKAP kinase 2. In addition, our results indicate that Hsp 27 may be target of phosphorylation events not only in the stress response but also in unstressed cells responding to cytokine stimulation.

Transforming growth factor (TGF)-alpha is a pleiotropic polypeptide which mediates a variety of tissue-specific cellular responses such as induction of proliferation, cell migration, vascularization, and formation of extracellular matrix. TGF-alpha is produced by certain tumor cells and embryogenic tissues, as well as by normal cells of different origin. Within the granulocytic lineage, TGF-alpha production has been shown in promyelocytic leukemia cells induced to differentiate, as well as in blood eosinophils of patients with the idiopathic hypereosinophilic syndrome. The present study was carried out in order to examine expression of the TGF-alpha gene in polymorphonuclear (PMN) and mononuclear (MN) blood cells of normal healthy donors. While MN and neutrophilic PMN failed to synthesize TGF-alpha transcripts and protein, eosinophils constitutively exhibited TGF-alpha transcripts accompanied by the release of immunoreactive TGF-alpha protein. Exposure of PMN and MN cells to the leukocyte-activating cytokines interleukin (IL)-3, IL-5, and granulocyte-macrophage colony-stimulating factor resulted in a several-fold increase of TGF-alpha mRNA expression and protein release by eosinophils, but not by neutrophils and MN cells. PMN and MN were insensitive to induction of TGF-alpha release by IL-8 and granulocyte colony-stimulating factor. These results point to a functional role of eosinophils in disorders characterized by unbalanced TGF-alpha production such as disease states associated with abnormal matrix formation and neovascularization which may be explained by the present demonstration of TGF-alpha production in these cells.

The product of the c-raf-1 proto-oncogene, Raf-1, is known to encode a 74-kDa ubiquitously expressed cytoplasmic serine/threonine kinase. Various growth factors such as epidermal growth factor, acidic fibroblast growth factor, platelet-derived growth factor, insulin, granulocyte-macrophage colony-stimulating factor, interleukin (IL)-2, IL-3 and erythropoietin have been shown to induce phosphorylation of Raf-1, thereby activating Raf-1 kinase. Raf-1 is, thus, believed to play a role in coupling growth factor receptors to proliferation. We have examined the role of Raf-1 in the mitogenic response of human peripheral blood-derived IL-2 receptor expressing T cells to human recombinant IL-2 employing c-raf antisense (AS) oligodeoxyribonucleotide. Uptake studies of oligonucleotides indicated that incorporation of oligomers was maximal at 4 h and oligodeoxynucleotides remained stable in these cells for up to 24 h. Treatment of T cells with the AS oligodeoxyribonucleotide in intracellular duplex formation followed by efficient translation blockade of c-raf-1. In contrast, sense (S) and nonsense (NS) oligodeoxynucleotides failed to form intracellular duplexes and did not interfere with translation of c-raf-1, suggesting specific elimination of c-raf-1 by the AS oligomer. Proliferation of T cells ([3H]thymidine incorporation) following exposure to IL-2 was substantially reduced when the c-raf-1 AS oligodeoxyribonucleotide was added to cultures, while the mitogenic response to this factor remained almost unaffected in the presence of S and NS oligodeoxyribonucleotides.

In the absence of appropriate stimuli, polymorphonuclear neutrophils (PMN) undergo programmed cell death (PCD), also termed apoptosis. We show that granulocyte-macrophage colony-stimulating factor (GM-CSF), but not the chemotactic factors formyl-methionyl-leucyl-phenylalanine (FMLP), recombinant human (rh) C5a, transforming growth factor (TGF)- beta, and interleukin-8 (IL-8), or other cytokines including IL-3, IL-4, IL-6, and G-CSF, maintains viability of PMN in culture by preventing these cells from undergoing PCD. Prevention from PCD by GM-CSF was associated with induction of RNA and protein synthesis in PMN. Inhibition of RNA and protein synthesis by actinomycin-D and cycloheximide impeded the protection of apoptosis by GM-CSF. Similarly, neutralization of GM-CSF biologic activity by a specific antiserum abrogated GM-CSF-mediated inhibition of PCD.

Recent studies have indicated that the leukemia inhibitory factor (LIF) induces secretion of interleukin-6 (IL-6) in myeloid cells. We here show that synthesis of IL-6 by human mononuclear phagocytes exposed to recombinant human (rh) LIF is preceded by an increase of IL-6 transcript levels as a result of transcriptional activation of the IL-6 gene. Analysis of deleted fragments of the IL-6 promoter indicated that transcriptional activation of the IL-6 promoter was associated with enhanced binding activity of the transcription factor nuclear factor (NF)-kappa B. Binding of activation protein (AP)-1 and NF-IL-6, also known to transcriptionally activate the IL-6 promoter, was not inducible by LIF. Furthermore, introduction of the NF-kappa B sequence into a heterologous promoter construct, but not of AP-1- and NF-IL-6- binding sequences, conferred inducibility by LIF to this promoter. Deletion of the NF-kappa B binding site in the IL-6 promoter was associated with loss of inducibility by LIF, lending further support for the notion that the NF-kappa B binding site is crucial for LIF- mediated induction of the IL-6 promoter. Taken together, our results show that rhLIF induces IL-6 gene expression in mononuclear phagocytes through transcriptional gene activation involving NF-kappa B.

The c-kit proto-oncogene encodes a transmembrane glycoprotein identical to the receptor for the recently cloned stem cell factor (SCF). The present study examines constitutive synthesis of transcripts in primary acute myelogenous leukemia (AML) blasts and the effects of recombinant human tumor necrosis factor (TNF)-alpha on c-kit mRNA expression in these cells. The c-kit transcripts were detectable at low levels in 10 of 10 different AML samples investigated. TNF treatment of AML cells was associated with enhanced c-kit mRNA expression in all specimens. Nuclear run-on transcription assays indicated that the c-kit gene was transcriptionally active in all leukemias examined and the rate of transcription was unaffected by exposure to TNF, suggesting posttranscriptional control mechanisms of c-kit mRNA accumulation. In the absence of TNF, the half-life of c-kit transcripts was 2 to 3 hours, while in TNF-treated AML cells, c-kit half-life was found to be 5 to 9 hours. Inhibition of protein synthesis reduced TNF-induced c-kit mRNA expression by Northern blot analysis, but did not affect the rate of c-kit gene transcription. In the presence of inhibition of protein synthesis, the half-life of c-kit transcripts in TNF-induced leukemia cells decreased to 2 to 4 hours. These findings indicate that levels of c-kit mRNA are controlled by a labile protein that is involved in TNF- mediated stabilization of c-kit transcripts. The effects of TNF-alpha also extended to the protein level in that TNF-alpha treatment of primary AMLs was associated with enhanced surface expression of the SCF receptor by some of these cells. While exogenous SCF induced clonogenic growth of all primary AML samples investigated, TNF-alpha failed to stimulate leukemic cells to proliferate. However, the combination of SCF and TNF-alpha resulted in synergistic growth stimulation in seven of nine different AML specimens investigated. The finding of transmodulation of the SCF receptor through posttranscriptional modifications might further contribute to our understanding of the synergistic interplay of TNF-alpha and SCF.

In a phase I study, the sequentially administered combination of recombinant human interleukin-3 (rhIL-3) and rhGM-CSF was compared with treatment with rhIL-3 alone in 15 patients with advanced tumors but normal hematopoiesis. Patients were initially treated with rhIL-3 for 15 days. After a treatment-free interval, the patients received a second 5-day cycle of rhIL-3 at an identical dosage, immediately followed by a 10-day course of rhGM-CSF, to assess the toxicity and biologic effects of this sequential rhIL-3/rhGM-CSF combination. rhIL-3 doses tested were 125, and 250 micrograms/m2, whereas rhGM-CSF was administered at a daily dosage of 250 micrograms/m2. Both cytokines were administered by subcutaneous (SC) bolus injection. rhIL-3/rhGM-CSF treatment was more effective than rhIL-3 but equally effective to each other in increasing peripheral leukocyte counts, especially neutrophilic and eosinophilic granulocyte counts. In contrast, both modes of cytokine therapy raised the platelet counts to the same degree. rhIL-3/GM-CSF treatment was more effective than rhIL-3 in increasing the number of circulating hematopoietic progenitor cells BFU- E and CFU-GM. High-dose rhIL-3, but not low-dose rhIL-3, was as effective as the rhIL-3/rhGM-CSF combinations in increasing the number of circulating CFU-GEMM. The increase in absolute neutrophil counts correlated with the increase in the number of circulating CFU-GM. Side effects, mainly fever, headache, flushing, and sweating, were generally mild, but in two patients the occurrence of chills, rigor, and dyspnea after initiation of GM-CSF treatment necessitated dose reduction and discontinuation, respectively. These results indicate that sequential treatment with rhIL-3 and rhGM-CSF is as effective as single-factor treatment with rhIL-3 in stimulating platelet counts, whereas the effect of combination therapy on neutrophil counts and circulating progenitor cells is superior.

This review article deals with the basic biological characteristics of the multifunctional cytokine interleukin-6 (IL-6) in man. Three central issues will be addressed more closely: the pathophysiological role of unbalanced IL-6 production in various disease states, the diagnostic usefulness of measurements of IL-6 in biological fluids, and the possible role of IL-6, IL-6 antagonists, and IL-6 derivatives as therapeutic tools in clinical medicine.

In this report we show that recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) and rh macrophage (M)-CSF induce accumulation of interleukin-1 beta (IL-1 beta) mRNA in blood-derived mononuclear phagocytes (MNP). GM-CSF and M-CSF treatment of MNP is also associated with IL-1 beta secretion. Regulation of GM- and M-CSF- induced IL-1 beta mRNA expression involves transcriptional and posttranscriptional mechanisms. However, the action of IL-3 on synthesis of IL-1 beta mRNA differs from that of other CSFs: While GM- CSF and M-CSF induce binding activity of the nuclear factor (NF) kappa B, IL-3 treatment of MNP has no profound effect on NF kappa B binding to DNA. Moreover, IL-3 decreases the transcription rate of the IL-1 beta gene and has only little effect on stability of IL-1 beta mRNA, which is increased by GM- and M-CSF. However, IL-3 enhances M-CSF- induced accumulation of IL-1 beta mRNA by unknown posttranscriptional means that may relate to an increased expression of M-CSF receptor (ie, c-fms) mRNA, detectable in mononuclear phagocytes on exposure to IL-3.

The cytogenetic hallmark of chronic myelogenous leukemia (CML) is the Philadelphia chromosome (Ph1), which reflects a chromosomal translocation t(9;22) and a rearrangement of the ABL and bcr genes. This marker is found in all cells arising from the same malignant precursor cell and can be detected in CML cells of the myeloid, monocytic, erythroid, and B-lymphocyte lineage. It is, however, controversial as to whether T lymphocytes of CML patients carry this gene rearrangement. An answer to this question would clarify whether the translocation in CML occurs in a pluripotent hematopoietic stem cell or in a precursor cell already committed to certain lineages, but not the T-cell lineage. To address this question, we established T-cell clones from peripheral venous blood cells of four patients with CML and screened these clones for bcr-abl fusion transcripts by means of polymerase chain reaction and Southern blot analysis. In four T-cell clones of three of these patients, the bcr-abl transcript could be detected. None of 12 T-cell clones of the fourth patient disclosed detectable bcr-abl amplification product. Both CD4+ as well as CD8+ clones displayed fused bcr-abl sequences. These data imply that in CML some but not all T lymphocytes may originate from the Ph1-positive stem cell.

Previous studies have shown that 1-beta-D-arabinofuranosylcytosine (ara- C) induces transcription of the c-jun immediate early response gene in human myeloid leukemia cells. The present work has examined the mechanisms responsible for this effect. Deleted forms of the c-jun promoter were linked to the chloramphenicol acetyltransferase (CAT) gene and transfected into KG-1 cells. The results demonstrate that ara- C-induced c-jun transcription is mediated by an element between positions -74 and -20 upstream to the start site. Electrophoretic mobility shift assays with the fragment f(-74/-20) showed an increase in binding with nuclear proteins from ara-C-treated cells as compared with untreated cells. Competition with an oligonucleotide containing the AP-1 consensus sequence indicated that ara-C stimulates binding of nuclear proteins at the AP-1 site in the c-jun promoter. These findings were confirmed in other gel shift studies with the collagenase enhancer AP-1 consensus sequence and with a DNA fragment containing an altered AP-1 site. The binding of JUN/AP-1 was maximal at 1 hour of ara-C treatment and decreased to baseline levels at 12 hours. The finding that ara-C induces AP-1 binding in the absence of protein synthesis indicated that this agent activates already synthesized JUN/AP-1. To confirm these findings, the AP-1 consensus sequence was introduced 5′ to the heterologous SV40 promoter. The results show that AP-1 enhances SV40 promoter activity in ara-C-treated cells. Taken together, these findings indicate that: (1) enhancement of JUN/AP-1 activity in ara-C- treated cells involves a posttranslational modification of JUN/AP-1; and (2) binding of activated JUN/AP-1 to the AP-1 site in the c-jun promoter confers ara-C inducibility of this gene.

Interleukin-3 (IL-3) is a glycoprotein belonging to the hematopoietic growth factor family that in preclinical in vitro and in vivo studies has exhibited a multilineage activity. Phase I/II trials with recombinant human IL-3 (rhIL-3) expressed in yeast are being done in patients with advanced malignancies as well as in patients with bone marrow failure states. Subcutaneous administration of rhIL-3 at dosages between 30 and 500 micrograms/m2 for 15 consecutive days has resulted in a dose-dependent increase in platelet counts as well as in a substantial increase in the number of circulating neutrophils, eosinophils, monocytes, and lymphocytes in patients with advanced malignancies but normal hematopoiesis. Erythropoiesis is less stimulated with an increase in hemoglobin concentration only in a minority of patients. In patients with secondary hematopoietic failure due to prolonged chemo-/radiotherapy or bone marrow infiltration by tumor cells, treatment with rhIL-3 leads to a clinically significant restoration of hematopoiesis, especially of thrombopoiesis and granulopoiesis. rhIL-3 has also been shown to improve neutrophil and platelet counts in patients with myelodysplastic syndromes, while improvement of hematopoiesis is rarely observed in patients with severe aplastic anemia with the presently used treatment schedules. Adverse effects of rhIL-3 are minor at the clinically used dosages and include fever, bone pain, headache, and stiffness of the neck. Transient thrombocytopenia has been observed in a few patients with myelodysplastic syndrome or aplastic anemia treated at dosages of 250-500 micrograms/m2. rhIL-3 is a multilineage hematopoietic cytokine with promising effects on platelet and neutrophil counts and special usefulness in patients with secondary hematopoietic failure.

We have examined the in vitro effects of recombinant human (rh) interleukin-1 (IL-1) on the growth of purified megakaryoblasts obtained from patients with acute megakaryoblastic leukemia. We demonstrate that both IL-1 alpha and IL-1 beta treatment of these cells led to stimulation of DNA synthesis (as shown by increase of 3H-thymidine incorporation up to 35-fold) and also resulted in colony formation of leukemic megakaryoblasts. However, the stimulatory effect of IL-1 was dependent on endogenous production of IL-6, because addition of neutralizing monoclonal antibody (MoAb) to IL-6 abrogated the stimulatory activity of IL-1. In contrast, neutralizing MoAbs to granulocyte (G)-colony stimulating factor (CSF), granulocyte-macrophage (GM)-CSF, and macrophage (M)-CSF failed to counteract the growth- enhancing effects of IL-1. Leukemic megakaryoblasts accumulated IL-6 mRNA and released IL-6 protein into their culture supernatant when exposed to rh IL-1 but failed to disclose transcripts for G-, GM-, and M-CSF under these conditions. Analysis of IL-6 receptor (IL-6R) transcript levels demonstrated that megakaryoblasts constitutively expressed IL-6R mRNA and that these transcripts are down-regulated to undetectable levels upon exposure to IL-1 and IL-6. Increase of 3H- thymidine incorporation by megakaryoblasts could be duplicated by exogenous IL-6 that could be blocked by neutralizing MoAb to IL-6. In conclusion, our results suggest that leukemic megakaryoblasts could produce and secrete IL-6, and express IL-6R, and that the growth- enhancing effect of IL-1 on these cells is indirect, via production of IL-6 by leukemic cells.

Transgenic animals or animals engrafted with retrovirus-derived expression vectors provide models for studying the in vivo effects of high and continuous serum levels of cytokines. Studies employing these models in order to analyze the biological effects for granulocytes-macrophages colony-stimulating factors (CSFs), granulocytes of interleukin (IL-)2, IL-3, IL-6 and erythropoietin are reviewed. In all of these models, overexpression of the different cytokines achieved by use of these approaches resulted in syndromes that were related to nonneoplastic hyperplasia of the respective target cell population. In some but not all models, these syndromes were lethal, mostly due to hypercellularity. These models allow conclusions about the biological effects of very high and continuous levels of these substances as well as about their regulation in different tissues.

In a phase I/II study, 19 patients with advanced tumors but normal hematopoiesis and nine patients with bone marrow failure and prolonged severe cytopenias were treated with recombinant human interleukin-3 (rhIL-3) to assess the toxicity and biological effects of this multipotential hematopoietic growth factor. Doses ranging from 30 micrograms/m2 to 500 micrograms/m2 were administered as subcutaneous bolus injection daily for 15 days. A dose-dependent increase in platelet counts ranging from 1.3-fold at 60 micrograms/m2 to 1.9-fold at 250 micrograms/m2 was induced by rhIL-3 in 15 of 18 evaluable patients with normal hematopoiesis. An increase in reticulocyte counts was observed in 14 patients. The blood leukocyte counts dose dependently increased 1.4- to 3.0-fold. In patients with bone marrow failure, platelet counts increased by a mean of sixfold (range, 1.3- fold to 14.3-fold) in five of eight evaluable patients. Reticulocyte counts increased 4.4-fold in six patients, and neutrophil counts increased by a mean of 3.1-fold in all eight patients. Platelet transfusions could be discontinued after treatment with rhIL-3 in two of three transfusion-dependent patients. Only mild side effects, mainly fever, headache, and flushing, were observed. These results indicate that rhIL-3 functions as a multilineage hematopoietin in vivo in patients with normal bone marrow function and in patients with secondary bone marrow failure.

In a phase I-II study, nine patients with myelodysplastic syndromes and concomitant severe transfusion-dependent cytopenias were treated with recombinant human interleukin-3 (rhIL-3) to improve hematopoietic function. Doses of rhIL-3 ranged from 250 micrograms/m2 to 500 micrograms/m2 and were given as daily subcutaneous bolus injections for 15 days. Blood leucocyte counts increased 1.3- to 3.6-fold in all nine patients, including neutrophils, eosinophils, lymphocytes, basophils, and monocytes. The mean absolute neutrophil counts increased from 1,350/microL (range, 150 to 2,420) to 2,660/microL (range, 300 to 9,380) (P less than .05) immediately after the end of rhIL-3 therapy and to a maximum count of 4,096/microL (range, 350 to 10,820) (P less than .01). Platelet responses were seen in two of four profoundly thrombocytopenic patients, resulting in discontinuation of platelet transfusion. The requirements for red blood cell transfusion temporarily improved in one patient. Stimulation of plasma cells was evident by a significant increase in serum IgM and IgA levels. Mild side effects (fever, headache, local erythema, and bone pain) were observed in some patients, while transient thrombocytopenia developed in two patients. Disease progression with an increase in blast cells was seen in one patient. These results suggest that rhIL-3 is effective in stimulating hematopoiesis of all lineages in patients with myelodysplastic syndromes and may produce at least short-term hematologic improvement.

80 Lipopolysaccharide binding protein: its role and therapeutical potential in inflammation and sepsis Ralf R. Schumann*, N. Lamping*, C. Kirschning*, H.-P. Knopft, A. Hoe& and F. Herrmann* *Max-Delbruck-Centrum fur Molekulare Medizin (MDC), Robert-Rossle-Str. 10, I3 I22 Berlin, Germany and Free University, Universitatsklinikum Rudolf-Virchow, Robert-Rossle Cancer Center, Department of Oncology and Applied Molecular Biology, Lindenberger Weg 80, I3 I22 Berlin, Germany, tMax-Planck-lnstitut fur Immunbiologie, Stubeweg 5 I , 79108 Freiburg, Germany and SMorphoSys GmbH, Frankfurter Ring 193A, 80807 Munchen, Germany

This case report describes the clinical use of recombinant human interleukin-3 as adjunct to immunosuppressive therapy with antilymphocyte globulin, cyclosporin A, and methylprednisolone for refractory severe aplastic anemia. Hematopoietic response to treatment was moderate and peripheral blood counts (neutrophils, eosinophils, monocytes, reticulocytes) increased only slightly. Unexpectedly, during the time of interleukin-3 administration a substantial bone marrow infiltration by macrophages became detectable, consistent with the diagnosis of medullary histiocytosis, that may have prevented recovery of normal hematopoiesis in this patient. This observation may indicate the need for careful use of interleukin-3 in patients with drug-induced immunodeficiency.

Despite enormous efforts focused on the development of new drugs and the use of novel drug combinations, including high-dose regimens supported by bone marrow and blood stem cell transplantation procedures, progress in the treatment of disseminated human cancer has been marginal. Remarkable advances in our understanding of the molecular biology of cancer has provided the possibility to employ new, selective tools of genetic intervention for more successful tumor treatment. We are now witnessing the inception of gene therapy. However, gene therapists face many drawbacks, including selectivity, specificity, sensitivity, and safety of gene transfer. Despite this there are already over 70 clinical protocols accepted for genetic approaches to cancer worldwide. Strategies currently under clinical investigation and discussed here include: (a) the enhancement of tumor immunogenicity by insertion of cytokine genes, genes coding for products of the major histocompatibility complex, and those for lymphocyte costimulatory ligands, (b) the vectoring of tumoricidal cytokines into cells that can potentially home on tumors to release their toxic products locally, (c) the use of tumor-specific pro-drug activators, i.e., the insertion of enzymatically pro-drug-activating genes fused to promoter systems which rely on differential (ideally tumorspecific) transcription control, (d) gene-marking strategies which may provide new indicators for minimal, residual, and relapsed tumor disease, (e) artificial repression of gene functions by insertion of genes encoding for complementary (antisense) mRNA to the gene of interest (e.g., oncogenes, drug resistance genes).

The multidrug transporter, P-glycoprotein (P-gp), is expressed by CD34-positive bone marrow cells, which include hematopoietic stem cells, and in other cells in the bone marrow and peripheral blood, including some lymphoid cells. Multidrug resistance mediated by P-gp appears to be a major impediment to successful treatment of acute myeloid leukemias and multiple myelomas. However, the impact of P-gp expression on prognosis has to be confirmed in several other hematopoietic neoplasms. The role of P-gp in normal and malignant hematopoiesis and clinical attempts to circumvent multidrug resistance in hematopoietic malignancies are reviewed. The recent transduction of the MDR1 gene into murine hematopoietic cells, which protects them from toxic effects of chemotherapy, suggests that MDR1 gene therapy may help prevent myelosuppression following chemotherapy.

Hematopoietic growth factors may be useful in improving the clinical effectiveness of arabinofuranosylcytosine (ara-C). In vitro studies have indicated that interleukin 3(IL-3) and, to a lesser extent, granulocyte-macrophage colony-stimulating factor (GM-CSF), but not G-CSF or M-CSF, may be capable of specifically augmenting the ability of ara-C to kill leukemic myeloid cells by pharmacological and cytokinetic mechanisms including increase of intracellular ara-CTP/dCTP pool ratios and enhanced ara-C DNA incorporation in leukemic blast cells, decrease of IC 90 of ara-C for leukemic colony-forming cells (CFC) as compared with normal CFC growth, and recruitment of quiescent leukemic cells into the cell cycle. In contrast, the combination of ara-C with M-CSF or with the leukemia inhibitory factor (LIF) appears to be useful in overcoming the block in differentiation of leukemic blast, while the effects of GM-CSF and IL-3 on ara-C-induced differentiation appear limited. The combined treatment of human myeloid leukemia cells by ara-C and LIF is associated with down-regulation of c-myc gene expression, transcriptional activation of jun/fos gene expression, and features of functional differentiation (e.g., the capability to reduce nitroblue tetrazolium, to express lysozyme, or to display differentiation-related surface receptors including C3bi and the c-fms protein). On the basis of these in vitro studies first clinical trials are underway that are examining the efficacy of ara-C combinations with these molecules for the treatment of myeloid disorders.

Leukotriene B4 (LTB4) is a notable participant in inflammation and chemotaxis. It is, however, still unclear whether LTB4 acts in this regard directly or indirectly by stimulating the release of chemotactic and inflammatory cytokines. Here we report that LTB4 induces synthesis of interleukin (IL)-6 by human blood monocytes through transcriptional activation of the IL-6 gene. We furthermore demonstrate that this process involves activation of the transcription factor NF-chi B and, to a lesser extent, of NF-IL6, while the activity of the transcription factor AP-1, shown to otherwise confer IL-6 inducibility, appeared to be unaffected by LTB4. Involvement of NF-chi B and NF-IL6 in induction of IL-6 transcription by monocytes was demonstrated using deleted forms of the IL-6 promoter. Activation of the IL-6 promoter by LTB4 was not only associated with accumulation of the respective transcripts but resulted in synthesis of functional IL-6 protein as well. In addition, LTB4 mediated transactivation of a heterologous promoter construct containing the NF-chi B or the NF-IL6 enhancer, but not the AP-1 enhancer. The signaling events mediating this effect appeared to involve the release of H2O2, since LTB4 failed to induce NF-chi B or NF-IL6 in the presence of the scavenger of H2O2, N-acetyl-L-cysteine.

This article covers the basic biological functions of interleukin-6 (IL-6) in man. Three major topics are addressed more closely: the involvement of IL-6 in various disease states, particularly those of hematopoietic origin; the diagnostic usefulness of IL-6 measurements in biological fluids; the possible use of IL-6, IL-6 antagonists or IL-6 derivatives as therapeutic means.

T cell clones were established from peripheral blood of a patient with severe aplastic anemia. 8 of 18 individual clonal T cell populations stably coexpressed CD4 andCD8 molecules, a phenotype characteristic for thymocytes and a minor subpopulation of circulating T lymphocytes. Analysis ofT cell receptor genes revealed identical rearrangements of T cell receptor # chain genes, suggesting clonality of theseT cells. CD4+/CD8' T cells clones were found to be efficiently cytotoxic towards autologous lymphoblasts. Autocytotoxicity could be blocked by a CD3 MAb, a MAb specific for monomorphicMHC class II determinants, and particularly, by an MHC-DP-specific MAb, suggesting specificity for autologous DP molecules. Perhaps more important, CD4+/CD8' T cell clones inhibited differentiation of autologous progenitor enriched bone marrow cells in vitro by a direct cell-mediated mechanism. These data suggest that circulating cytotoxic CD4+/CD8'T cell clones specific for autologousMHC-DP determinants may be involved in hematopoietic failure in some cases ofaplastic anemia. (J. Clin. Invest.

Peripheral blood-derived human polymorphonuclear leukocytes (PMNL) can be induced to synthesize prostaglandin E2 (PGE2) from endogenous and exogenous arachidonic acid (AA) when exposed to agents such as human recombinant (hr) granulocyte-macrophage (GM) colony-stimulating factor (CSF), hr tumor necrosis factor-alpha, hr granulocyte (G)-CSF, lipopolysaccharide and the chemoattractant N-formyl-methionyl-leucyl-phenylalanine. Treatment of PMNL with hr macrophage (M)-CSF and interleukin 3, however, did not result in detectable PGE2 synthesis. Cytokines stimulated PGE2 production during two distinct time intervals, an early peak of PGE2 that was detectable at 20 min and a late one detectable after 4 h. Inhibition of protein synthesis by cycloheximide (CHX) had virtually no effect on the early increase of PGE2 but prevented the late increase. Late addition of CHX to cultures after stimulation with hr GM-CSF at 4 h resulted in decline of PGE2 synthesis from exogenous arachidonic acid. Treatment of PMNL with GM-CSF had direct effects on cyclooxygenase (COx). PMNL depleted from COx by acetyl salicylic acid (ASA) recovered to synthesize PGE2 following exposure to GM-CSF. Recovery from COx inhibition by ASA could be prevented by CHX.

Alpha- and gamma-interferons have been shown to actively suppress hematopoiesis in patients in the chronic phase of chronic myelogenous leukemia in vitro and in vivo. Since both interferons act through different receptors on their hematopoietic target cells, they are expected to be capable of independently inhibiting abnormal blood cell development in patients with chronic myelogenous leukemia. We have utilized recombinant human interferon alfa-2c to treate 11 patients with Philadelphia chromosome positive chronic myelogenous leukemia in chronic phase, who were resistant to previous interferon gamma therapy. Ten of the patients were evaluable for hematologic, cytogenetic and molecular-genetic response following interferon alfa-2c therapy for 6 to 30 months. In 5 patients, IFN alfa-2c treatment failed due to lack of hematologic response. A complete hematologic or partial hematologic response was achieved in the remaining 5 patients. Three of these experienced cytogenetic improvement with reappearence of 100% diploid hematopoietic cells and disappearence of c-abl/bcr rearrangement in one patient. In two patients interferon alfa-2c did not prevent transformation of the disease into an accelerated state or blast crisis, respectively. We conclude that recombinant human interferon alfa-2c may also control hematopoiesis in interferon-gamma resistant chronic myelogenous leukemia patients, although the long-term response will need to be elucidated in further studies.

In a phase I/II study, nine patients with aplastic anemia were treated with recombinant human interleukin-3 (rhIL-3) to assess the toxicity and biologic effects of this multipotential hematopoietic growth factor. Doses ranging from 250 micrograms/m2 to 500 micrograms/m2 were administered as subcutaneous bolus injections daily for 15 days. An increase in platelet counts from 1,000/microL to 31,000/microL was induced by rhIL-3 in one patient, and an increase in reticulocyte counts by more than 10,000/microL in four patients. The blood leukocyte counts temporarily increased in eight patients 1.5- to 3.3-fold (median, 1.8-fold), mainly due to an increase in the number of neutrophils, eosinophils, lymphocytes, and monocytes. In two patients, bone marrow cellularity increased from 7% to 33% and from 10% to 80%, respectively, but without resulting in a substantial improvement of peripheral blood counts. Mild side effects (headache and flushing) were observed in some patients, while low-grade fever occurred in all patients. Transient thrombocytopenia necessitating discontinuation of rhIL-3 treatment occurred in one patient. In conclusion, rhIL-3 can stimulate hematopoiesis in patients with aplastic anemia; however, no lasting effects were obtained.

Proliferation of acute myelogenous leukemia (AML) derived blast cells requires the presence in culture of one or more growth factors. In the majority of cases Interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) stimulate clonogenicity of AML blasts, which can be synergised by Interleukin-6 (IL-6), Interleukin-1 (IL-1) and granulocyte colony-stimulating factor (G-CSF). In contrast, macrophage colony-stimulating factor (M-CSF) favors deterministic divisions. A substantial part of AML samples have clonogenic cells which, however, proliferate autonomously in vitro. The production by leukemic cells of a variety of growth or synergizing factors including GM-CSF, G-CSF, IL-1, IL-6, and Tumor Necrosis Factor (TNF) has been demonstrated and a fraction of cases will use these molecules to support clonogenic growth in an autocrine or paracrine fashion. However, unlike the situation with retrovirus-induced murine or avian leukemias, the role of production of CSFs and other cytokines by human leukemic cells in the transformational process remains uncertain.

purpose: A phase Ib/II clinical study was undertaken to assess the efficacy of recombinant human (rh) granulocyte-macrophage colony-stimulating (GM-CSF) factor in attenuating neutropenia and associated morbidity caused by high-dose anticancer chemotherapy administered in the presence or absence of autologous bone marrow support. patients and methods: Twenty-two patients with various solid tumors and lymphoid neoplasias were treated with a single daily subcutaneous dose of rh GM-CSF (250/μg/m 2 ) 48 hours after receiving a second cycle of highly myelotoxic chemotherapy for a period of 10 days. Within-subject comparisons on neutropenia-related clinical and laboratory variables were made with data obtained from the same patients after they received the first neutropenia-inducing cycle of identical chemotherapy in the absence of GM-CSF. results: GM-CSF was active in neutropenic patients because it significantly increased the neutrophilic nadir, reduced the time of relevant neutropenia, and reduced the duration of a patient's hospital stay and the necessity for parenteral antibiotics. No significant toxicity was encountered with subcutaneous GM-CSF treatment. conclusion: Although GM-CSF was shown to significantly reduce chemotherapy-associated morbidity in patients receiving myelotoxic cancer chemotherapy, additional studies are needed to assess whether the use of GM-CSF in anticancer chemotherapy will allow an increase in the dosage level, leading to improved response rates and survival among cancer patients.

In this paper we demonstrate that maturing neoplastic cells from patients with chronic myelogenous leukemia (CML) constitutively produce G-CSF and are also receptive for this molecule. G-CSF functions as an autocrine growth factor in stable phase CML, and thus is responsible for divisions of maturing leukemic cells leading to an expansion of the compartment of mature cells. This observation is well in line with in vivo features of CML in stable phase, i.e., the hyperplasia of the mature granulocyte compartment. In acute blastic phase of CML expression of the G-CSF gene seems to be less common and not related to autonomous blast growth.

Myelosuppression-related neutropenia is the major side effect of most anticancer chemotherapy. Despite considerable improvements in supportive care due to the advent of a variety of new antibiotic combinations, infection remains the main risk arising during the neutropenic period that follows intensive chemotherapy for cancer [1]. In addition, neutropenia is the major obstacle to dose escalation, frequency of cytoreductive treatment, and thus to improved cancer control. Regarding reduction of the period of neutropenia and increase of the maximum tolerated dose of effective anticancer agents, autologous bone marrow transplantation (ABMT) has recently offered new promise. However, as many as 5% of patients having undergone ABMT die prior to engraftment with neutropeniarelated infections as the major contributing cause [2].

This article summarises the effects of colony-stimulating factors and related molecules on leukemia blasts by focussing on autocrine and paracrine growth control. This information may lead to a better understanding of the pathobiology of this highly malignant disorder, and may have therapeutic implications.

Treatment of patients having myelodysplastic a syndromes (MDS) with approaches such as differentiation induction, single cytostatic agents or supportive care only has, up to now, been rather unsuccessful. Aggressive chemotherapy followed by bone marrow transplantation is only suitable for a very small proportion of patients. Thus, there is a need for new therapeutic alternatives.

regretfully informs its readers that the above-named publication has been cited in the Report of the Joint Investigative Commission for the Appraisal of Allegations of Fraud in Science (August 4, 1997), presided by Dr. W. Gerok, as erroneous. For this reason the above-named publication is, with consent of the co-authors, hereby retracted. (The Editorial Committee of JMM)

We studied the effects of a series of well-characterized clones of human natural killer (NK) cells on the proliferation of highly purified normal marrow hematopoietic progenitor cells. Individual NK clones suppressed granulocyte, monocyte, erythroid, or mixed colony formation in a heterogeneous but clonally stable manner. Inhibition of colony growth required a period of close cell contact between NK cell and progenitor cell with maximum inhibition occurring after 8 to 18 hours of preincubation time. The mechanism of killing was at least partially humoral, however, as cell-free supernatants generated by NK clones “activated” by contact with a target cell also inhibited progenitor cell growth. One of the possible humoral mediators was identified as gamma-interferon by studies with specific neutralizing monoclonal antibodies. These results show that clonal NK lines can be further activated by coming in contact with hematopoietic progenitor cells, resulting in substantial inhibition of colony formation in vitro.

Proliferation of acute myeloblastic leukemia (AML) cells in vitro is limited in most cases to a small subset of blasts that have several properties of stem cells. These leukemic colony-forming cells (AML-CFU) generally require addition of exogenous growth factors for proliferation in agar or methylcellulose. These factors can be supplied by media conditioned by phytohemagglutinin-stimulated normal leukocytes or by CSF-secreting tumor cell lines. However, the exact factor or factors required for stimulation of AML-CFU growth have not been defined. We compared the AML-CFU stimulatory activity of a human recombinant GM-CSF with that of GCT-CM, Mo-CM, and the PHA-leukocyte feeder system in 15 cases of AML. In each of the 12 cases that required exogenous growth factors for maximum AML-CFU growth, recombinant GM-CSF could replace either GM-CSF or Mo-CM, and could partially replace the PHA-leukocyte feeder system. These results indicate that this GM-CSF is a growth promoter of AML-CFU in these culture systems.

A high proportion of acute myeloid leukemias (AML) recently investigated for their capacity to synthesize biologically active bioregulatory molecules was found to accumulate messenger (m) RNA and to produce membrane-bound or -secreted forms of stimulating factors for granulocyte, macrophage and mixed granulocyte-macrophage colony growth. Blast cells have also been found to secrete interleukin 1, tumor necrosis factor-alpha, interleukin 6, and to express receptors for various growth factors as well. However, growth factors like interleukin 2 and interleukin 3 have not been identified as AML products, and several other factors including interleukin 4, interleukin 5, etc. need further evaluation. Responsiveness of clonogenic leukemic cells to exogenous growth-promoting factors in vitro suggests a possible role of these biomolecules in the course of these disorders. Important evidence for the crucial role of growth factors, at least in some subtypes of AML, has been provided by demonstrating constitutive growth factor production by leukemic cells and their autonomous in vitro growth which is dependent on autocrine secretion of a specific growth factor. The concert of mechanisms providing stimulatory and inhibitory signals for hematopoiesis, which is adapted to the various physiological requirements of the organism, may have multiple defects in AML. This leads to successive steps of malfunctioning of cells, which finally express a fully malignant phenotype. In addition, these derangements also lead to defects in accessory cells on the level of mediator communication. However, there is evidence for autonomous growth promotion of AML blast by constitutive production of growth factors active in an autocrine fashion (GM-CSF, G-CSF, interleukin 6) and by recruitment of accessory cells to increase CSF supply (GM-CSF, G-CSF) via molecules such as interleukin 1 and TNF-alpha in a paracrine fashion. Molecular analysis of transformed hematopoietic cells has revealed changes of the genome, e.g., insertion of viral genetic information or cytogenetic fractures at DNA sites controlling growth factor gene activation. These events appear to be crucial in the induction of uncontrolled growth factor expression promoting oncogenic transformation of hematopoietic progenitor cells.

Lymphocytes from two patients with T gamma cell proliferations displaying the morphology of large granular lymphocytes (LGL) were characterized in terms of cell marker phenotyping and immunologic functions. In both patients, the lymphocytes were positive for E-R, HuTLA, OKT5, OKT8, OKT11, OKM1, VEP13, Leu1, Leu2a, Lyt2 and Lyt3 and were negative for Tmu, Tar, SIg, BA1, BA2, EM-R, C3d-R, C3b-R, OKT6, OKT9, Leu3a, OKIa1 and TdT. In addition, investigations for T411, T811 and M522 in patient 1 yielded positive results. There were differences in the phenotype of the two patients with regard to the reactions with OKT3, OKT10 and VEP10. While, in patient 1, OKT3 was very pronounced and OKT10 and VEP10 were completely negative, OKT10 and VEP10 were very pronounced in patient 2, whereas OKT3 was positive only in a very small percentage of cells. Though the lymphocytes in both patients were potent effectors of NK and K functions (patient 2 more strongly than patient 1) and a noticeably reduced mitogen response was shown to PHA, Con A and zinc, patient 1 showed a distinct suppression of allogenic and autologous B cell response to transformation into ISC, coinciding with the clinical observation of a hypogammaglobulinemia; neither B cell suppression nor dysgammaglobulinemia was seen in patient 2. The results are discussed with regard to other comparable T gamma proliferations reported in the literature.

Colony-stimulating factors are required for survival proliferation, differentiation and functional activation of granulocytes, macrophages and their precursor cells. In the present report, however, we demonstrate antiproliferative activity of recombinant human (rh) granulocyte-macrophage colony-stimulating factor (GM-CSF) on monoblast cell line U-937 and provide evidence for the involvement of tumor necrosis factor alpha TNF-alpha and interleukin 1 beta (IL 1 beta) in its growth inhibitory action. GM-CSF (but not granulocyte CSF, G-CSF or macrophage CSF, M-CSF) suppressed DNA synthesis and self renewal of U-937 cells. Similarly, medium conditioned by U-937 cells in response to GM-CSF (GM-CSF U-937-CM) was able to reduce clonogenicity and [3H]thymidine uptake by U-937 cells. Since neutralization of GM-CSF present in GM-CSF U-937-CM by monoclonal antibody to GM-CSF did not abrogate the autoinhibitory activity present in GM-CSF U-937-CM, we considered the possibility that other soluble molecules are released by U-937 cells upon GM-CSF stimulation. Neutralization by antibodies to IL 1 beta and TNF-alpha suggested that both monokines could be the antiproliferative principle operating in GM-CSF U-937-CM. Moreover, employing IL 1 beta-specific enzyme-linked immunosorbent assay, TNF-alpha specific radioimmunoassay, Northern analysis using a cloned TNF-alpha-specific cDNA and an oligonucleotide probe for IL 1 beta, we demonstrate GM-CSF-inducible IL 1 beta and TNF-alpha gene expression by U-937 cells at the mRNA and protein level. Although M-CSF expression was induced under similar conditions, M-CSF failed to inhibit growth of U-937 cells.

We assessed the capacity of recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) and multilineage (Multi)-CSF to induce release of granulocyte-CSF (G-CSF) by highly purified peripheral blood monocyte (Mo) preparations. Our results reveal that GM-CSF and Multi-CSF, either alone or in a synergistic concert, activate Mo to transcribe G-CSF messenger (m) RNA and release biologically active G- CSF protein into their culture supernatants. G-CSF had no regulatory effect on Mo expression of cytoplasmic G-CSF mRNA levels and G-CSF protein secretion by itself. These differential actions of CSFs provide further insight into self-regulatory mechanisms within the growth factor hierarchy system.