Interrelationship and expression profiling of cyclooxygenase and angiogenic factors in Indian patients with multiple myeloma.

Multiple myeloma (MM) is classically illustrated by a desynchronized cytokine system with rise in inflammatory cytokines. There are recent reports which emphasized the potential role of angiogenesis in the development of MM. Role of cyclooxygenase 2 (COX-2) is well documented in the pathogenesis of solid tumors, but little is known about its occurrence and function in hematologic neoplasms. Involvement of neoangiogenesis is reported in the progression of MM, and angiopoietins probably contribute to this progression by enhancing neovascularization. Circulatory and mRNA levels of angiogenic factors and cyclooxygenase were determined in 125 subjects (75 MM patients and 50 healthy controls) by using enzyme-linked immunosorbent assay and quantitative PCR. We observed significant increase for angiogenic factors (Ang-1, Ang-2, hepatocyte growth factor, and vascular endothelial growth factor) and cyclooxygenase at circulatory level, as well as at mRNA level, as compared to healthy controls except insignificant increase for Ang-1 at circulatory level. We have also observed the significant positive correlation of all angiogenic factors with cyclooxygenase. The strong association found between angiogenic factors and COX-2 in this study may lead to the development of combination therapeutic strategy to treat MM. Therefore, targeting COX-2 by using its effective inhibitors demonstrating antiangiogenic and antitumor effects could be used as a new therapeutic approach for treatment of MM.

T cells from patients with polycythemia vera elaborate growth factors which contribute to endogenous erythroid and megakaryocyte colony formation.

In the present study, we report that media conditioned by polycythemia vera (PV) CD3+ cells promote BFU-E and CFU-Mk colony formation by both cord blood and PV peripheral blood CD34+ cells in the absence of exogenous cytokines and promoting megakaryocyte proplatelet formation. CD3+ cells constitutively produce elevated levels of IL-11, while stimulation with the addition of phytohemagglutinin (PHA) increased GM-CSF levels in most of the patients with PV. Anti-IL-11-neutralizing antibody partially inhibited the formation of BFU-E and CFU-Mk colonies promoted by PV CD3+ cell-conditioned media. Although IL-11 is not produced by normal T cells, real-time PCR and flow cytometric analysis showed that IL-11 was upregulated in the CD3+ cells of most PV patients as compared to normal CD3+ cells. In addition, a greater percentage of BFU-E colonies formed by PV CD34+ cells in the presence of PV CD3+ cell-conditioned media alone were JAK2V617F-positive as compared with that induced by EPO. We conclude that dysregulated production of soluble growth factor(s), including IL-11 and GM-CSF by PV T cells, contributes to the in vitro formation of erythroid colonies in the absence of exogenous cytokines by PV CD34+ cells and likely plays a role in sustaining hematopoiesis in PV.

Activation of individual tumor necrosis factor receptors differentially affects stem cell growth factor and cytokine production.

Necrotizing enterocolitis (NEC) is an emergency of the newborn that often requires surgery. Growth factors from stem cells may aid in decreasing intestinal damage while also promoting restitution. We hypothesized that 1) TNF, LPS, or hypoxia would alter bone marrow mesenchymal stem cell (BMSC) TNF, IGF-1, IL-6, and VEGF production, and 2) TNF receptor type 1 (TNFR1) or type 2 (TNFR2) ablation would result in changes to the patterns of cytokines and growth factors produced. BMSCs were harvested from female wild-type (WT), TNFR1 knockout (KO), and TNFR2KO mice. Cells were stimulated with TNF, LPS, or hypoxia. After 24 h, cell supernatants were assayed via ELISA. Production of TNF and IGF-1 was decreased in both knockouts compared with WT regardless of the stimulus utilized, whereas IL-6 and VEGF levels appeared to be cooperatively regulated by both the activated TNF receptor and the initial stimulus. IL-6 was increased compared with WT in both knockouts following TNF stimulation but was significantly decreased with LPS. Compared with WT, hypoxia increased IL-6 in TNFR1KO but not TNFR2KO cells. TNF stimulation decreased VEGF in TNFR2KO cells, whereas TNFR1 ablation resulted in no change in VEGF compared with WT. TNFR1 ablation resulted in a decrease in VEGF following LPS stimulation compared with WT; no change was noted in TNFR2KO cells. With hypoxia, TNFR1KO cells expressed more VEGF compared with WT, whereas no difference was noted between WT and TNFR2KO cells. TNF receptor ablation modifies BMSC cytokine production. Identifying the proper stimulus and signaling cascades for the production of desired growth factors may be beneficial in maximizing the therapeutic potential of stem cells.

Expression, refolding, and characterization of a novel recombinant dual human stem cell factor.

A novel recombinant dual human stem cell factor (rdhSCF) gene which consisted of a full-length hSCF(1-165aa) cDNA and a truncated hSCF (1-145aa) cDNA, linked by a peptide (GGGGSGGGGSGG) coding region, was constructed and cloned into Escherichia coli expression vector pET-22b. The rdhSCF was expressed at high level in E. coli BL21(DE3) and existed mainly as inclusion bodies. The inclusion bodies were solubilized in urea and refolded by ion-exchange chromatography. After renaturation, the purity of the yielded rdhSCF was up to 90%. Cell proliferation assay showed that the specific activity of the rdhSCF was 2.86x10(5) U/mg, about 1.66 times as high as that of monomer rhSCF expressed in E. coli.

Increased blood myeloid dendritic cells and dendritic cell-poietins in Langerhans cell histiocytosis.

Langerhans cell histiocytosis (LCH), previously known as histiocytosis X, is a reactive proliferative disease of unknown pathogenesis. Current therapies are based on nonspecific immunosuppression. Because multiple APCs, including Langerhans cells and macrophages, are involved in the lesion formation, we surmised that LCH is a disease of myeloid blood precursors. We found that lin(-) HLA-DR(+)CD11c-+ precursors of dendritic cells, able to give rise to either Langerhans cells or macrophages, are significantly (p = 0.004) increased in the blood of LCH patients. The analysis of serum cytokines in 24 patients demonstrated significantly elevated levels of hemopoietic cytokines such as fms-like tyrosine kinase ligand (FLT3-L, a dendritic cell-mobilizing factor, approximately 2-fold) and M-CSF ( approximately 4-fold). Higher levels of these cytokines correlated with patients having more extensive disease. Serum levels of FLT3-L and M-CSF were highest in high risk patients with extensive skin and/or multisystem involvement. Finally, patients with bone lesions had relatively higher levels of M-CSF and of stem cell factor. Thus, early hemopoietic cytokines such as FLT3-L, stem cell factor, and M-CSF maybe relevant in LCH pathogenesis and might be considered as novel therapeutic targets.

Endurance exercise and the production of growth hormone and haematopoietic factors in patients with anaemia.

BACKGROUND: Physical activity has been shown to stimulate haematopoiesis in patients with anaemia due to chronic renal failure or haematological malignancies. OBJECTIVE: To evaluate the effect of moderate exercise on the production of haematopoietically active factors. METHODS: Ten patients (four men and six women, mean (SD) age 51 (10) years) with a haemoglobin concentration under 130 g/l (men) or 120 g/l (women) carried out five three minute exercise bouts at an intensity of 80% of the maximal heart rate, corresponding to a lactate concentration of 3 (0.5) mmol/l. Patients rested for three minutes between bouts. The concentrations of interleukin 6, stem cell factor, granulocyte-monocyte colony stimulating factor, granulocyte colony stimulating factor, erythropoietin, and growth hormone (GH) were evaluated before and in the eight hours after exercise. RESULTS: GH had risen significantly 15 minutes after exercise (1.1 (1.3) v 2.7 (2.8) ng/ml; p<0.05). No change in the concentration of the other cytokines and growth factors was observed in the eight hours after exercise. CONCLUSIONS: In patients with anaemia, submaximal exercise does not affect the concentration of haematopoietically active cytokines. However, it leads to an increased concentration of GH. This may be responsible for the improved haematopoiesis observed after an exercise programme in patients with chronic diseases.

G-CSF therapy of ongoing experimental allergic encephalomyelitis via chemokine- and cytokine-based immune deviation.

Converging evidence that G-CSF, the hemopoietic growth factor of the myeloid lineage, also exerts anti-inflammatory and pro-Th2 effects, prompted us to evaluate its direct therapeutic potential in autoimmune diseases. Here we report a novel activity of G-CSF in experimental allergic encephalomyelitis, a murine model for multiple sclerosis, driven by Th1-oriented autoaggressive cells. A short 7-day treatment with G-CSF, initiated at the onset of clinical signs, provided durable protection from experimental autoimmune encephalomyelitis. G-CSF-treated mice displayed limited demyelination, reduced recruitment of T cells to the CNS, and very discrete autoimmune inflammation, as well as barely detectable CNS mRNA levels of cytokines and chemokines. In the periphery, G-CSF treatment triggered an imbalance in the production by macrophages as well as autoreactive splenocytes of macrophage inflammatory protein-1alpha and monocyte chemoattractant protein-1, the prototypical pro-Th1 and pro-Th2 CC chemokines, respectively. This chemokine imbalance was associated with an immune deviation of the autoreactive response, with reduced IFN-gamma and increased IL-4 and TGF-beta1 levels. Moreover, G-CSF limited the production of TNF-alpha, a cytokine also associated with early CNS infiltration and neurological deficit. These findings support the potential application of G-CSF in the treatment of human autoimmune diseases such as multiple sclerosis, taking advantage of the wide clinical favorable experience with this molecule.

Myeloid hematopoietic growth factors and their role in prevention and/or treatment of neonatal sepsis.

Sepsis continues to be an important cause of morbidity and mortality among both full-term and preterm infants, secondary to an immaturity in neonatal host defense. The incidence of neonatal sepsis ranges from 30% in very low birth weight infants to 0.4% in preterm neonates and 0.1% in term neonates. The dysregulation of the expression and production of hematopoietic cytokines in the neonate contributes to quantitative and qualitative deficiencies in neonatal myeloid progenitor activity and decreased availability and function of mature effector neutrophils. These abnormalities contribute in large part to the increased incidence and mortality associated with neonatal sepsis. In this review, we have summarized and analyzed the studies investigating the dysregulation, expression and production of myelopoietic growth factors in neonates, the preclinical in vivo effects of myelopoietic growth factors in neonatal animals, the preclinical in vivo effects of myelopoietic growth factors during experimental sepsis in neonatal animals, the in vitro effects of growth factors on human neonatal phagocytic immunity, and clinical results of myelopoietic growth factors in human neonates. Future studies should be focused on investigating other abnormalities of neonatal host defense and multiple and simultaneous approaches to circumvent identified defects to attempt to reduce both the incidence and severity of neonatal host defense.

Interleukin-18 stimulates hematopoietic cytokine and growth factor formation and augments circulating granulocytes in mice.

Because interleukin-18 (IL-18) is similar to IL-1 and is known to be involved in the hematopoietic progenitor cell growth, the effect of IL-18 on circulating cell populations was examined. Repeated administration of IL-18 induced significant amounts of neutrophilia in mice. In parallel, high levels of interferon-gamma (IFN-gamma), IL-6, and granulocyte-macrophage colony-stimulating factor (GM-CSF) were detected in the serum of these mice. Interestingly, the cytokine profiles as well as the cell populations in circulation altered around 2 weeks after the beginning of IL-18 administration. A weak but definite eosinophilia was observed concurrently with the appearance of serum IL-5. Consistent with these observations, IL-18 induced secretion of IFN-gamma, GM-CSF, and IL-6 from splenocytes in culture. IL-18 also induced low levels of IL-5 in the splenocyte culture, which was inhibited by IL-12. However, markedly high levels of IL-5 were secreted into the culture medium when splenocytes from IFN-gamma-deficient mice were stimulated by IL-18. CD4(+) T cells strongly responded to IL-18 to secrete IL-5 and GM-CSF. IL-18 stimulated secretion of IL-6 and expression of G-CSF mRNA in splenic adherent cells. Expression of IL-18 receptors was detected in CD4(+) T cells and splenic adherent cells (macrophages). These results show that IL-18 stimulates CD4(+) T cells and macrophages to secrete IL-5, GM-CSF, IL-6, and granulocyte-colony stimulating factor in the absence of IL-12, which in turn induces hematopoietic cell proliferation causing neutrophilia and eosinophilia in mice.

Effects of hexadecylphosphocholine on thrombocytopoiesis.

Hexadecylphosphocholine (HePC) is the first representative of the alkylphosphocholines, a novel group derived from the cytotoxic etherlysophospholipids. HePC shows a broad spectrum of antiproliferative effects in neoplastic cells in vitro and in vivo. HePC has been tested successfully in several clinical studies. One of the remarkable features of this compound has been the induction of a leucocytosis and a thrombocytosis in most of the patients receiving HePC systemically. In this paper, we have investigated the biological and molecular mechanisms by which HePC exerts this interesting effect. We found that HePC acts as an unspecific costimulator on human megakaryocytic proliferation in a soft agar assay system predominantly together with thrombopoietin (TPO). Furthermore, HePC leads to the synthesis and secretion of several haematopoietic growth factors in monocytes and bone marrow fibroblasts, determined by the direct measurement of growth factors in cellular supernatants and by the measurement of growth factor mRNA in cell extracts. Thus, HePC seems to produce the increase of blood platelets in tumour patients by two different mechanisms.

[The murine submandibular gland conditioned medium induce the development of CFU-GM and CFU-meg].

OBJECTIVE: Our purpose is to determine whether murine submandibular gland produce hematopoietic growth factors or not and which hematopoietic growth factor are produced by murine submandibular gland. METHODS: By using the techniques of culture of hematopoietic progenitor cells(CFU-GM, CFU-Meg) ex vivo, flow-cytometry, the effects of murine submandibular gland conditioned medium(SGCM) on the development of CFU-GM and CFU-Meg in mice was studied. RESULTS: SGCM can stimulate the development of CFU-GM and CFU-Meg (without any exogeneous HGF), almost no colony in control (without any exogeneous HGF and SGCM); the promoting activity of male SGCM is higher than female SGCM's in augmenting colony formation of CFU-Meg (P < 0.05), there is no difference of CFU-GM(P > 0.05). The stimulating activity of anemic mice SGCM is higher normal mice SGCM's (P < 0.05). IL-3 can collaborate with female SGCM to stimulate proliferation of CFU-Meg. SGCM can promote bone morrow cell entiring the active proliferative phase(S/G2). CONCLUSION: Submandibular gland can stimulate the development of CFU-GM and CFU-Meg by secreting hematopoietic growth factor-like activities. Our study provide the experimental evidences for clarifying the relationship between submandibular gland and hematopoiesis.

[Effect of human umbilical vein endothelial cells on granulopoiesis, erythropoiesis and megakaryopoiesis in mice].

OBJECTIVE: To investigate the effects of endothelial cells on the proliferations of granulocytic, erythrocytic and megakaryocytic progenitor cells. METHODS: Human umbilical vein endothelial cells were collected within 12 hours after cesarean section and were cultured according to Jaffe's method. The human endothelial culture supernatant (HECS) harvested from primary culture medium was centrifuged. Bone marrow mononuclear cells of mice were prepared and then cultured in semi-solid agar or methylcellulose with the addition of HECS. RESULTS: Colony-forming yields were increased in the culture systems with HECS. But in the systems with no HECS, exogenous GM-CSF, EPO and IL-3 added to the hematopoietic progenitor cultures were necessary to induce colony-forming. Synergistic increase in progenitor cell expansion was observed when both HECS and exogenous cytokines were added to hematopoietic progenitor cultures. CONCLUSION: 1. Endothelial cells can support the proliferation and differentiation of hematopoietic stem and progenitor cells. 2. HECS as a source of standard hematopoietic growth factors can be used in the expansion of stem cells in vitro and in the therapy of hemopathy. 3. Interactions between endothelial cells and hematopoietic stem cell or progenitors may play an important role in the regulation of hematopoiesis in vivo. 4. Endothelial cells may produce other soluble growth factors potentiating the action of a set of cytokines such as GM-CSF and IL-6.

Production and pre-clinical significance of haematopoietic peptide growth factors (HPGF) in human non-seminomatous germ cell tumour cell lines.

Peptide growth factors involved in the regulation of haematopoiesis (HPGF), for example granulocyte-colony-stimulating factor (G-CSF) and granulocyte/macrophage-colony-stimulating factor (GM-CSF), are of clinical importance in the treatment of testicular germ cell tumour (GCT) patients with modern chemotherapy regimens since they ameliorate chemotherapy-induced neutropenia. Aberrant expression of and/or response to HPGF has been reported in several solid tumour types although no data are available on GCT with the exception of those on stem cell factor (SCF). The aims of this pre-clinical study were twofold: (1) to screen a panel of human non-seminomatous (NS)GCT for the production of HPGF and (2) to test the effects of G-CSF or SCF on the growth of NSGCT cell lines in vitro, and on the growth kinetics of two human NSGCT xenograft models. HPGF concentrations in cell culture supernatant from 11 NSGCT cell lines growing under routine culture conditions were measured by enzyme-linked immunosorbent assay. The growth kinetics of cell lines was quantified in vitro using the sulphorhodamine B assay. The growth kinetics of nude mouse NSGCT xenografts was followed by measuring tumour volumes every 2-3 days over days 1-30, following daily subcutaneous injection of nude mice (days 1-14). The cell lines produced G-CSF (1/11 cell lines), GM-CSF (2/11), SCF (2/11), M-CSF (6/11). and interleukin-6 (9/11). Growth stimulation of cell line H12.1 by SCF was observed in vitro, but no statistically significant differences in NSGCT xenograft tumour volume (VT) or relative VT (r VT) in treated groups were observed on days 14 or 29 compared to the control. The change in rVT of H12.1 xenografts treated with G-CSF alone compared to control (rVT/rVT,c) was 0.96 on day 29. The values for rVT/rVT,c for H12.1 xenografts treated with G-CSF in combination with low- or high-dose SCF were, respectively, 1.67 or 1.7 compared to 1.19 for SCF-treated mice. The results are in agreement with clinical data to date where no observations have been reported of stimulation or inhibition of tumours in patients receiving treatment with G-CSF. Before any clinical trials are initiated in GCT patients treated with G-CSF in combination with SCF, further pre-clinical experiments with this tumour type are recommended to investigate this phenomenon further in a greater number of NSGCT cell lines in vitro and in vivo and with a wider range of SCF/G-CSF schedules. The potential relevance of secretion of HPGF in NSGCT cell lines in vitro to the pathobiology of GCT in patients is also a subject of interest for future research.

Mutual education between hematopoietic cells and bone marrow stromal cells through direct cell-to-cell contact: factors that determine the growth of bone marrow stroma-dependent leukemic (HB-1) cells.

A stroma-dependent cell line (HB-1) was established from myelogenous leukemic cells of CBA/N mouse. Characterization of the cells showed that HB-1 proliferated on hematopoietic supportive stromal cells (MS-10), but did not survive or proliferate on hematopoietic nonsupportive cells (MS-K). Direct contact between HB-1 and MS-10 appears to be necessary for HB-1 to proliferate on MS-10. We found that interleukin-1alpha (IL-1alpha) produced by MS-10 plays a major role in the survival and proliferation of HB-1. IL-11 did not support the proliferation of HB-1 cells by itself, but enhanced the proliferation of HB-1 cells in the presence of IL-1alpha. The expression of IL-1alpha and IL-11 was induced in MS-10 by the direct contact with HB-1 cells, and the expression of IL-1 receptor type I (IL-1RI) and interleukin-11 receptor (IL-11R) was induced in HB-1 cells by the attachment of the cells to MS-10. These findings show the existence of two-way interactions between HB-1 and MS-10.

Mannuronan enhances survival of lethally irradiated mice and stimulates murine haematopoiesis in vitro.

Mannuronan (poly-beta-(1-->4)-D-mannuronate or poly-M), produced by Pseudomonas aeruginosa as a mucoid exopolysaccharide, has previously been shown to exhibit immunostimulating activity. The authors investigated the in vivo and in vitro effects of mannuronan on murine haematopoiesis. In vivo, prophylactic (-24 h, intraperitoneal) administration of mannuronan enhanced survival of lethally irradiated mice from zero day 40 survivors (NaCl) to 20, 80 and 70% survival at 0.5, 1 and 2 mg/kg bw mannuronan, respectively. In vitro, primary stromal cultures stimulated with mannuronan produced high levels of interleukin(IL)-1, IL-6 and colony stimulating activity. Mannuronan alone did not have any colony stimulating activity on GM-CFC, BFU-E, Mix-CFC or HPP-CFC progenitors in clonogenic assays, but acted synergistically with suboptimal amounts of growth factors on GM-CFC, Mix-CFC and HPP-CFC colony formation. Limiting dilution analysis showed that 1 of 423 bone marrow cells formed colonies in response to suboptimal GM-CSF plus mannuronan compared to 1 of 592 for suboptimal GM-CSF alone. The primitive Lin-Sca-1+ haematopoietic progenitors showed increased day 10 colony size in the presence of mannuronan in single cells assays. These stimulating effects of mannuronan on haematopoiesis may prove to have clinical importance.

The role of cytokines and hematopoietic growth factors in the autocrine/paracrine regulation of inducible hematopoiesis.

To elucidate the role of hematopoietic growth factors (HGFs) and other cytokines in the autocrine or paracrine regulation of inducible hematopoiesis we studied cytokine gene expression in the bone marrow (BM) of patients after myelosuppressive treatment. Furthermore, we studied the cytokine gene expression profile in healthy individuals before and after bone marrow harvesting for the purpose of bone marrow transplantation. We speculated that the bone marrow harvesting procedure might induce changes in cytokine gene expression. No induction of G-CSF, GM-CSF, IL-1 alpha, IL-3, IL-5, IL-8, IL-9, and IL-12 was observed in the BM of patients following intensive chemotherapy. Also, no up-regulation of expression of M-CSF, IL-1 beta, IL-4, IL-6, TNF-alpha, TGF-beta, IGF-1, EDF, and EPA gene was found, illustrating that the investigated cytokines probably are not relevant in the presumed autocrine/paracrine regulation of the recovery of hematopoiesis following depletion of hematopoietic progenitor cells (HPCs). Concomitantly, elevated G-CSF plasma levels were found in these patients, suggesting that G-CSF has an endocrine regulatory role in inducible hematopoiesis. Induction of GM-CSF and IL-8, but not of G-CSF or IL-3 gene expression and upregulation of IL-1 beta and IL-6 gene following BM harvesting was observed. This induction of GM-CSF and IL-8 may be attributed to tissue damage rather than to HPC depletion.

Differential regulation of proinflammatory and hematopoietic cytokines in human macrophages after infection with human immunodeficiency virus.

Cells of the macrophage lineage (MAC) play an important role in human immunodeficiency virus (HIV) infection. However, the knowledge on the extent of macrophage involvement in the pathogenesis of HIV infection is still incomplete. In this study we examined the secretory repertoire of HIV-infected MAC with respect to the proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), IL-6, IL-8, and the hematopoietic growth factors M-, G- and granulocyte-macrophage colony stimulating factor (GM-CSF). Using a culture system on hydrophobic teflon membranes, blood-derived MO from healthy donors were infected with a monocytotropic HIV-1 isolate (HIV-1D117IIII). We analyzed the constitutive and lipopolysaccharides-stimulated secretion of MO/MAC early after infection as well as in long-term cultured, virus-replicating cells. The release of proinflammatory mediators and hematopoietic growth factors were differentially regulated after infection with HIV: the secretion of TNF-alpha, IL-1 beta, IL-6, IL-8 was upregulated, whereas a down-regulation of M-, G-, and GM-CSF could be observed. These results may provide some explanation for the immunological dysfunction, the hematopoietic failure and the chronic inflammatory disease occurring in HIV-infected patients.

Inadequate production of hematopoietic growth factors in hairy cell leukemia: up-regulation of interleukin 6 by recombinant IFN-alpha in vitro.

The course of hairy cell leukemia (HCL) is characterized by progressive pancytopenia. The pathogenesis of this phenomenon is still not fully understood. To study if the decrease in hematopoiesis in HCL is accompanied by abnormal concentrations of growth factors, we investigated the production of granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, interleukin 3 (IL-3), interleukin 6 (IL-6), and tumor necrosis factor alpha by peripheral blood mononuclear cells (PBMCs) of eight patients with HCL. The results point to a severe deficiency of production of all cytokines tested as compared to healthy donors. However, enrichment of autologous monocytes by counterflow centrifugation resulted in a marked increase of the levels of granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, IL-6, and tumor necrosis factor alpha. The most pronounced effects were seen with IL-6. Reverse transcription-PCR analysis indicated that pokeweed mitogen, IFN-alpha, and poly(I:C) are capable of inducing the expression of IL-6-specific mRNA in HCL cells. These findings are substantiated on the protein level by immunofluorescence analysis. Incubation of PBMCs with IFN-alpha resulted in a significant increase of intracellular IL-6 in HCL but not in healthy donors. This increase was also seen in hairy cells positive for CD19 and CDllc. Furthermore, IFN-alpha induced the secretion of IL-6 from PBMCs of HCL patients but not healthy donors. In conclusion, our studies with PBMCs from patients with HCL revealed an inadequate supply of hematopoietic growth factors that might, in part, be due to the monocytopenia characteristic for this disease. The findings also indicate that IFN-alpha is capable of inducing the production of IL-6 in the patients' PBMCs as well as in their hairy cells. These data from our in vitro studies support the clinical observation that treatment with IFN-alpha leads to reconstitution of hematopoiesis.

Structure-activity relationships of novel hematoregulatory peptides.

Hematopoiesis is a lifelong cell renewal process regulated by a family of lineage specific hematopoietic growth factors. Several hematopoietic growth factors such as G-CSF, GM-CSF, and M-CSF have been clinically evaluated for enhancement of host defense in normal and immunocompromised patients and for the treatment of infectious diseases. This paper reports the structure-activity relationships of low molecular weight hematoregulatory peptides based on a nonapeptide (1, SK&F 107647). Like the macromolecular growth factors, these peptides modulate host defense. A molecular target for this class of compounds has not yet been identified. However, the structure-activity relationships established by this study implicate a very specific molecular recognition event that is pivotal for the biological activities of 1 and its analogues.