IFN-beta selectively down-regulates transferrin receptor expression in human peripheral blood macrophages by a post-translational mechanism

We evaluated the effect of IFN-beta on the expression of transferrin receptor (TfR) during the in vitro differentiation of peripheral blood monocytes to macrophages. IFN-beta exerted a strong inhibitory effect on the expression of TfR. As little as 0.1 IU/ml was sufficient to induce a 40% reduction of transferrin (Tf) binding sites on 7-day cultured macrophages. Scatchard plot analysis revealed that this impaired Tf binding in IFN-beta-treated macrophages was not due to a decreased affinity of the TfR for its ligand but to a reduction in the number of cell surface TfR. IFN-gamma did not exert any significant effect on the expression of TfR, even though it was capable of partially reverting the inhibitory effect of the IFN-beta on Tf binding. To understand the mechanism by which IFN-beta inhibited TfR expression, we examined the expression of TfR mRNA, 125I-Tf binding to detergent-solubilized cells, and TfR cellular distribution. The results of these experiments showed that IFN-beta caused neither a significant alteration of the expression of TfR mRNA nor a decrease of the total content of TfR molecules. Moreover, immunofluorescence analysis of TfR localization indicated that TfR was clustered in an intracellular compartment in IFN-beta-treated macrophages. These data demonstrate that IFN-beta is capable of dramatically down-modulating TfR in macrophages by post-translational mechanisms (i.e., by sequestering this receptor in intracellular compartments).

Cytokine regulation of astrocyte function: in-vitro studies using cells from the human brain

Participation of astrocytes in central nervous system pathophysiology is likely to involve cytokines, both as stimulators and mediators of astrocyte function. We have used highly enriched human astrocyte cultures as an experimental tool to investigate the influence of cytokines on adhesion molecule expression and synthesis of mediators that are probably important in immune and inflammatory reactions involving the nervous system and in cerebral tissue repair. The response of astrocytes to interferon-gamma mainly resulted in increased expression of major histocompatibility complex antigens and co-stimulatory molecules (intercellular adhesion molecule-1, LFA-1 alpha) which mediate astrocyte-T-cell interactions. Another co-stimulatory molecule, B7, was neither expressed nor inducible by IFN-gamma and other cytokines. TNF-alpha and IL-1 beta were more efficient in stimulating synthesis of immunoregulatory and proinflammatory cytokines (IL-6, IL-8 and colony-stimulating factors), cytokine antagonists (TNF-alpha soluble receptors), or cytokines with a possible neuroprotective role (leukemia inhibitory factor); they also increased expression of some co-stimulatory molecules (intercellular adhesion molecule-1 and vascular cell adhesion molecule-1). Transforming growth factor-beta 1 was a strong inducer of leukemia inhibitory factor, but did not affect either major histocompatibility complex/co-stimulatory molecule expression or cytokine synthesis. Thus, different cytokines activate distinct functional programs in astrocytes, which may play a specific role in different brain diseases or at different stages of the same disease. It was additionally observed that the response of human astrocytes to cytokines (in particular the inducible synthesis of certain cytokines) varied greatly depending on the presence or absence of neurons in the culture system. This finding suggests that neuronal-glial interactions may be implicated in determining the activation threshold of astrocytes to inflammatory cytokines.

Modulation of retinoblastoma gene in normal adult hematopoiesis: peak expression and functional role in advanced erythroid differentiation

The retinoblastoma (RB) gene specifies a nuclear phosphoprotein (pRb 105), which is a prototype tumor suppressor inactivated in a variety of human tumors. Recent studies suggest that RB is also involved in embryonic development of murine central nervous and hematopoietic systems. We have investigated RB expression and function in human adult hematopoiesis--i.e., in liquid suspension culture of purified quiescent hematopoietic progenitor cells (HPCs) induced by growth factor stimulus to proliferation and unilinage differentiation/maturation through the erythroid or granulocytic lineage. In the initial HPC differentiation stages, the RB gene is gradually induced at the mRNA and protein level in both erythroid and granulopoietic cultures. In late HPC differentiation and then precursor maturation, RB gene expression is sustained in the erythroid lineage, whereas it is sharply downmodulated in the granulocytic series. Functional studies were performed by treatment of HPC differentiation culture with phosphorothioate antisense oligomer targeting Rb mRNA; coherent with the expression pattern, oligomer treatment of late HPCs causes a dose-dependent and selective inhibition of erythroid colony formation. These observations suggest that the RB gene plays an erythroid- and stage-specific functional role in normal adult hematopoiesis, particularly at the level of late erythroid HPCs.

Differential expression and functional role of GATA-2, NF-E2, and GATA-1 in normal adult hematopoiesis

We have explored the expression of the transcription factors GATA-1, GATA-2, and NF-E2 in purified early hematopoietic progenitor cells (HPCs) induced to gradual unilineage erythroid or granulocytic differentiation by growth factor stimulus. GATA-2 mRNA and protein, already expressed in quiescent HPCs, is rapidly induced as early as 3 h after growth factor stimulus, but then declines in advanced erythroid and granulocytic differentiation and maturation. NF-E2 and GATA-1 mRNAs and proteins, though not detected in quiescent HPCs, are gradually induced at 24-48 h in both erythroid and granulocytic culture. Beginning at late differentiation/early maturation stage, both transcription factors are further accumulated in the erythroid pathway, whereas they are suppressed in the granulopoietic series. Similarly, the erythropoietin receptor (EpR) is induced and sustainedly expressed during erythroid differentiation, although beginning at later times (i.e., day 5), whereas it is barely expressed in the granulopoietic pathway. In the first series of functional studies, HPCs were treated with antisense oligomers targeted to transcription factor mRNA: inhibition of GATA-2 expression caused a decreased number of both erythroid and granulocyte-monocytic clones, whereas inhibition of NF-E2 or GATA-1 expression induced a selective impairment of erythroid colony formation. In a second series of functional studies, HPCs treated with retinoic acid were induced to shift from erythroid to granulocytic differentiation (Labbaye et al. 1994. Blood. 83:651-656); this was coupled with abrogation of GATA-1, NF-E2, and EpR expression and conversely enhanced GATA-2 levels. These results indicate the expression and key role of GATA-2 in the early stages of HPC proliferation/differentiation. Conversely, NF-E2 and GATA-1 expression and function are apparently restricted to erythroid differentiation and maturation: their expression precedes that of the EpR, and their function may be in part mediated via the EpR.

Combined vitamin D3/retinoic acid induction of human promyelocytic cell lines: enhanced phagocytic cell maturation and hybrid granulomonocytic phenotype

Studies on the effect of retinoic acid (RA) and 1,25-dihydroxyvitamin (D3) on the differentiation of leukemic cells have provided insight into the cellular and molecular mechanisms underlying hematopoietic cell differentiation. We have evaluated the combined effect of these chemical inducers on the differentiation of HL-60 and AML-193 promyelocytic leukemia cell lines. Simultaneous RA+D3 addition potentiated leukemic cell maturation up to mature phagocytic cells. Interestingly, AML-193 cells induced with D3 and RA displayed a typical neutrophilic morphology while exhibiting properties specific to monocytic cells, e.g., high expression of CD14 membrane antigen, capacity to bind bacterial lipopolysaccharide, and monocytic-specific esterase activity; this hybrid granulomonocytic (GM) phenotype was not observed upon initial incubation with one inducer and later addition of the other. Parallel control studies were performed with purified normal GM progenitors, triggered by interleukin 3+GM-colony-stimulating factor (CSF) in FCS-rich or -free clonogenic culture, by GM-CSF+M-CSF in FCS-rich clonogenic culture, and by M-CSF in liquid suspension culture. The progenitors grown in the first condition generate exclusively G clones, even upon addition of D3 and/or RA. The progenitors grown in the second and third culture conditions generate either G and M clones (second culture condition) or a population of cells composed by a majority of monocytes (third culture condition); the D3 addition did not modify this differentiation pattern, whereas RA or RA+D3 addition elicited a marked inhibition of monocytic differentiation. These observations suggest that the development of a hybrid GM phenotype is restricted to the progeny of bipotent GM leukemic precursors.

The costimulatory molecule B7 is expressed on human microglia in culture and in multiple sclerosis acute lesions

B7 is a costimulatory molecule which is expressed on antigen-presenting cells and which plays a pivotal role in T cell activation and proliferation. To elucidate mechanisms regulating intracerebral immune responses, expression of B7 was examined in cultured microglial cells and in brain tissue from control and multiple sclerosis patients. Using immunocytochemical and polymerase chain reaction techniques, we show that B7 was expressed in cultured microglial cells from the human embryonic brain. Microglia also bound the soluble form of the B7 receptor CTLA-4 (CTLA-4-Ig). B7 gene expression and binding of anti-B7 antibodies and CTLA-4-Ig increased after treatment with interferon-gamma. B7 was not inducible in human astrocytes. Human microglia expressed other costimulatory molecules, such as intercellular adhesion molecule-1, LFA-1 and LFA-3. In sections of multiple sclerosis brains, B7 immunoreactivity was detected on activated microglia and infiltrating macrophages within active lesions. In chronic lesions, only perivascular cells were stained. B7 immunoreactivity was undetectable in sections from Alzheimer's disease or normal brain tissue. These data suggest that B7 may be involved in T cell activation and lesion development in multiple sclerosis and that the regulated expression of B7 on microglia may contribute to the local stimulation of T cell proliferation and effector functions.

In vitro human immunodeficiency virus-1 infection of purified hematopoietic progenitors in single-cell culture

Uni- or multi-lineage suppression of hematopoiesis is observed in the majority of acquired immunodeficiency syndrome (AIDS) patients. The mechanism(s) underlying these abnormalities is not understood: particularly, the human immunodeficiency virus (HIV) infection of hematopoietic progenitor and stem cells (HPCs/HSCs) is highly controversial. We report that CD34+ HPCs from adult peripheral blood (PB) are in part CD4+ and susceptible to in vitro HIV infection. Primitive CD34+ HPCs were approximately 80% purified from PB. Double labeling for CD34 and CD4 membrane antigens was shown for 5% to 20% of the purified cells, thus suggesting their potential susceptibility to HIV-1 infection. The enriched HPC population, challenged with purified or unpurified HIV-1 strains, was cloned in unicellular methylcellulose culture. The single colonies generated by erythroid burst-forming units (BFU-E), granulocyte-macrophage colony-forming units (CFU-GM), and granulocyte-erythroid-macrophage-megakaryocyte colony-forming units (CFU-GEMM) were analyzed for the presence of HIV, ie, for gag DNA, tat mRNA, and p24 protein by PCR, reverse transcription PCR (RT-PCR), and enzyme-linked immunosorbent assay, respectively. In the first series of experiments incubation of HPCs with HIV-1 at multiplicities of infection (MOI) ranging from 0.01 to 10 TCID50/cell consistently yielded an 11% to 17% infection efficiency of BFU-E-generated colonies, thus indicating the sensitivity of HPCs to in vitro HIV infection. An extensive series of experiments was then performed on HPCs challenged with HIV at 0.1 MOI level. In the initial studies proviral gag sequences were detected in 9.2% of 121 analyzed CFU-GM colonies. In further experiments tat mRNA was monitored in 17% and 23% of BFU-E and CFU-GM colonies, respectively, but never in CFU-GEMM clones. Finally, 12% of CFU-GM clones and rare erythroid bursts were shown to be positive for the p24 viral protein. In control studies, purified HPCs grown in liquid suspension culture were induced to terminal unilineage erythroid, monocytic, or granulocytic differentiation: monocytes were consistently HIV-infected, whereas mature-terminal erythroblasts and granulocytes were not. Our observations indicate that a minority of primitive HPCs, but not of the multipotent type, is susceptible to in vitro HIV infection. These observations may reflect on the in vivo hematopoietic impairment in AIDS patients; more important, they provide an experimental model for studies on HIV hematopoietic infection and in vitro tests for anti-HIV HSC gene therapy.

Prognostic significance of interleukin 6 serum levels in patients with ovarian cancer

High levels of IL-6 were found in 50% of 114 patients with primary ovarian cancer. IL-6 sensitivity was lower than that of CA 125, and the combination of both assays did not increase the sensitivity of CA 125 alone. However, elevated IL-6 serum levels were correlated with a poor prognosis since patients with low IL-6 levels had a better survival than patients with high IL-6 levels (P = 0.0009). Multivariate analysis revealed that IL-6 positivity has an independent value.

Promyelocytic leukemia-specific PML-retinoic acid alpha receptor fusion protein interferes with erythroid differentiation of human erythroleukemia K562 cells

Acute promyelocytic leukemia (APL) is characterized by a t(15;17) chromosomal translocation with breakpoints within the retinoic acid alpha receptor (RAR alpha) gene on 17 and the PML gene, which encodes a putative transcription factor, on 15. A PML-RAR alpha fusion protein is formed as a consequence of the translocation. We show here that expression of the PML-RAR alpha protein in K562 erythroleukemia cells results in a reduced expression of erythroid differentiation markers and a reduced sensitivity to the erythroid differentiative action of heme. Overexpression of RAR alpha, but not of PML, elicited a similar inhibition of K562 erythroid differentiation. These findings indicate that overexpression of either RAR alpha or PML/RAR alpha interferes with erythroid differentiation and support the hypothesis that RAR alpha is involved in the regulation of normal hematopoiesis and alteration of the RAR alpha signaling by PML/RAR alpha is implicated in the promyelocytic leukemogenesis.

Combined interleukin-1 beta/interleukin-6 treatment in mice: synergistic myelostimulatory activity and myelorestorative effect after cyclophosphamide-induced myelosuppression

We have studied the effects of single and combined treatment with recombinant human interleukin 1 beta (IL-1 beta) and recombinant human interleukin-6 (IL-6) on spleen and bone marrow hematopoiesis in normal and cyclophosphamide-treated mice. Injection of IL-1 beta alone resulted in a significant increase in the number of granulocytes and splenic progenitors [burst-forming units-erythroid (BFU-E) and colony-forming units-granulomonocytic (CFU-GM)] as compared with control mice but did not markedly enhance the number of bone marrow BFU-E and CFU-GM. IL-6 alone had little effect on the number of splenic progenitors but significantly increased the number of marrow BFU-E and CFU-GM, especially after a 6-day cytokine treatment. Combined daily administration of IL-1 beta and IL-6 for 3 days resulted in a synergistic stimulation of hematopoiesis as evaluated by the number of spleen and bone marrow CFU-GM and BFU-E colonies. Likewise, IL-1 beta/IL-6 markedly enhanced the number of circulating neutrophils, whereas each cytokine alone had little or no effect. When the numbers of spleen progenitors and peripheral granulocytes were determined 1 day after the last injection, a synergistic myelostimulatory effect of combined IL-1 beta/IL-6 treatment was observed at all doses (IL-1 beta, 0.25-0.5 microgram; IL-6, 1-20 micrograms). Furthermore, combined treatment with IL-1 beta/IL-6 accelerated and potentiated the recovery of myeloid cells after cyclophosphamide injection, whereas the single regimen treatment was not effective. Particularly, the rebound of WBC (especially neutrophilic granulocytes) after cyclophosphamide treatment was markedly enhanced by the combined treatment, whereas the single regimen was ineffective. Altogether these results may contribute to the development of combination therapies with cytokines and antiblastic agents in the treatment of cancer patients.

Key functional role and lineage-specific expression of selected HOXB genes in purified hematopoietic progenitor differentiation

Although it is well established that homeobox (HOX) genes play a key role in normal human embryogenesis, the expression and function of HOX genes in normal hematopoiesis is largely unknown. We have investigated by reverse transcriptase-polymerase chain reaction the mRNA expression of HOXB cluster genes (3' to 5' position in the cluster: from HOXB2 through B9) in 72% to 88% purified hematopoietic progenitor cells (HPCs) from adult peripheral blood induced in liquid suspension culture to gradual erythroid or granulopoietic (largely eosinophilic) differentiation and maturation by differential growth factor (GF) stimulus (ie, low-dose interleukin-3 [IL-3] and granulocyte-macrophage colony-stimulating factor [GM-CSF] and high-dose erythropoietin, or saturating amounts of IL-3/GM-CSF, respectively). Only B3 is expressed in quiescent HPCs. After GF treatment B3 expression is enhanced in the initial 24 hours and then through differentiation and maturation in erythroid and granulopoietic cultures. HOXB4 and B5 are induced at slightly later times and expressed through maturation in both lineages, whereas B6 is selectively induced in granulocytic differentiation. B2 is transiently expressed at low level in the granulopoietic pathway, whereas it is detected only in advanced stages of erythropoiesis: B7, B8, and B9 are essentially not detected. Functional studies were performed with antisense phosphorothioate oligomers to HOX mRNAs and included control analysis of the targeted mRNA. The results are strictly coherent with the HOX mRNA expression pattern: (1) anti-B3 oligomer (alpha-B3) treatment of purified HPCs induces a striking blockade of both erythroid and granulomonocytic colony formation (similarly, alpha-B3 treatment of K562 cell line causes a significant dose-related inhibition of cell proliferation); (2) alpha-B6 selectively and markedly inhibits granulomonocytic colony formation; (3) alpha-B4 and alpha-B5 cause a significant, less pronounced decrease of both colony types; (4) finally, alpha-B2 and alpha-B7, -B9 exert little and no effect, respectively. These studies provide novel evidence on the coordinate expression of selected HOXB cluster genes in erythropoiesis and granulopoiesis, particularly in the early stages of differentiation: B3 apparently functions as a master gene in early hematopoiesis, whereas B6 exerts a key selective function in the granulopoietic pathway.

Efficient transfer of selectable and membrane reporter genes in hematopoietic progenitor and stem cells purified from human peripheral blood

We have utilized highly purified hematopoietic progenitor and stem cells (HPCs, HSCs) from normal peripheral blood to develop methodology for: (a) efficient transfer into HPCs of a non-hematopoietic membrane reporter, i.e., the nerve growth factor receptor complementary DNA; and (b) effective gene transduction of putative HSCs, i.e., cells initiating Dexter-type long-term culture (LTC-ICs). Purified HPCs induced into cycling by growth factors (interleukin 3, interleukin 6, c-kit ligand) were transduced with the N2 retroviral vector containing the neomycin resistance (neor) gene. More than 80% of transduced HPCs were resistant to the toxic G418 level. Thereafter, the HPCs were effectively transduced with the LNSN retroviral vector containing a nerve growth factor receptor complementary DNA; the nerve growth factor receptor was detected on > or = 18% of the transduced HPCs. These experiments provide a new tool from which (a) to monitor expression of a transduced membrane report on hematopoietic cells, particularly at the level of HPCs/HSCs, and (b) to characterize the transduced cells by double- and triple-labeling membrane antigen analysis. Purified HPCs/HSCs grown in Dexter-type LTC were transduced at 1 week by exposure to supernatant N2 retroviral particles in the absence of exogenous hematopoietic growth factors. The procedure, devoid of toxic effects, allowed an efficient neor transduction into LTC-ICs. Thus, we consistently detected neomycin-resistant mRNA in the clonal progeny of HPCs produced in LTC at 5-8 weeks in both the nonadherent and adherent fractions; this timing of expression coincides with that of HPC production by LTC-ICs, thereby indicating the effective transduction of the LTC-ICs. These experiments represent a first step toward development of preclinical models for gene transfer into human peripheral blood HSCs by complex retroviral vectors.

Coordinate expression and proliferative role of HOXB genes in activated adult T lymphocytes

We investigated the expression of HOXB cluster genes in purified phytohemagglutinin (PHA)-activated T lymphocytes from normal adult peripheral blood by reverse transcription PCR and RNase protection. These genes are not expressed in quiescent T cells, except for barely detectable B1 RNA. After the PHA stimulus, HOXB gene activation initiates coordinately as a rapid induction wave in the 3'-->5' cluster direction (i.e., from HOXB1 through B9 genes). Thus, (i) expression of the foremost 3'-located B1 and B2 genes peaks 10 min after PHA addition and then rapidly declines, (ii) activation of B3, B4, and B5 begins 10 min after PHA addition and peaks at later times (i.e., at 120 min for B5), (iii) B6, B7, and B9 are expressed at a low level starting at later times (45 to 60 min), and (iv) B8 remains silent. Treatment of PHA-activated T lymphocytes with antisense oligonucleotides to B2 or B4 mRNA causes a drastic inhibition of T-cell proliferation and a decreased expression of T-cell activation markers (i.e., interleukin 2 and transferrin receptors). Similarly, treatment of CEM-CCRF, Peer, and SEZ627 T acute lymphocytic leukemia cell lines with anti-B4 oligomer markedly inhibits cell proliferation. Finally, T cells stimulated by a low dosage of PHA in the presence of 1 microM retinoic acid show a marked increase of both HOXB expression, particularly B2, and cell proliferation. These studies provide novel evidence on the role of HOX genes in adult cell proliferation. (i) Coordinate, early activation of HOXB genes from the 3'-->5' cluster side apparently underlies T-cell activation. (ii) The expression pattern in adult PHA-activated T cells is strikingly similar to that observed in retinoic acid-induced teratocarcinoma cells (A. Simeone, D. Acampora, L. Arcioni, P. W. Andres, E. Boncinelli, and F. Mavilio, Nature (London) 346:763-766, 1990), thus suggesting that molecular mechanisms underlying HOX gene expression in the earliest stages of development may also operate in activated adult T lymphocytes.

Regulation of leukemia inhibitory factor synthesis in cultured human astrocytes

We have examined the ability of human astrocytes to synthesize and secrete leukemia inhibitory factor (LIF), which is a multifunctional cytokine that controls cell proliferation and differentiation in many tissues, including the nervous system. Astrocyte-enriched cultures, prepared from 8- to 9-wk-old embryonic brains, expressed LIF mRNA and secreted LIF protein. LIF synthesis was significantly increased by the cytokines IL-1 beta, TNF-alpha, and TGF-beta 1, but not by IFN-gamma, IL-6, or LPS. No major differences in basal and cytokine-inducible LIF production were detected among astrocyte populations obtained from different brain areas. LIF synthesis was lower in serum-free than in serum-containing astrocyte cultures. A role for protein kinase C in the regulation of astrocyte LIF production was suggested by the findings that phorbol esters induced both LIF mRNA and protein and that the cytokine-induced LIF increase was partially antagonized by relatively selective inhibitors of protein kinase C such as H7 and staurosporine. Human leptomeningeal fibroblasts also expressed LIF gene and protein. Astrocytes produced LIF and responded to cytokines with increased LIF synthesis only after being subcultured, and not when grown in primary cultures in close contact with neurons. Our findings suggest that in vivo induction of astrocyte LIF secretion might occur in pathologic conditions as a consequence of both alterations of neuronal-glial interactions and a local increase in the level of inflammatory cytokines.

Regulation of leukemia inhibitory factor synthesis in cultured human astrocytes

We have examined the ability of human astrocytes to synthesize and secrete leukemia inhibitory factor (LIF), which is a multifunctional cytokine that controls cell proliferation and differentiation in many tissues, including the nervous system. Astrocyte-enriched cultures, prepared from 8- to 9-wk-old embryonic brains, expressed LIF mRNA and secreted LIF protein. LIF synthesis was significantly increased by the cytokines IL-1 beta, TNF-alpha, and TGF-beta 1, but not by IFN-gamma, IL-6, or LPS. No major differences in basal and cytokine-inducible LIF production were detected among astrocyte populations obtained from different brain areas. LIF synthesis was lower in serum-free than in serum-containing astrocyte cultures. A role for protein kinase C in the regulation of astrocyte LIF production was suggested by the findings that phorbol esters induced both LIF mRNA and protein and that the cytokine-induced LIF increase was partially antagonized by relatively selective inhibitors of protein kinase C such as H7 and staurosporine. Human leptomeningeal fibroblasts also expressed LIF gene and protein. Astrocytes produced LIF and responded to cytokines with increased LIF synthesis only after being subcultured, and not when grown in primary cultures in close contact with neurons. Our findings suggest that in vivo induction of astrocyte LIF secretion might occur in pathologic conditions as a consequence of both alterations of neuronal-glial interactions and a local increase in the level of inflammatory cytokines.

Interleukin-6 serum levels in patients with gynecological tumors

Serum levels of IL-6 were evaluated in a large group of patients with benign or malignant gynecological tumors. The results obtained were correlated with the patients' clinicopathological features and follow-up data. Using a highly sensitive immunoenzymatic method for the evaluation of serum IL-6 levels, we observed that > 95% of normal healthy women exhibited values within the range of 1.9-6 pg/ml. Using a cut-off of 6 pg/ml, elevated levels of serum IL-6 were found in 53% of 45 patients with primary epithelial ovarian cancer and less frequently in patients with endometrial and cervical cancer (37% and 10% respectively). Elevated levels of IL-6 were occasionally seen in patients with benign disease. IL-6 serum levels appeared to be less sensitive than CA 125 in ovarian cancer diagnosis. In cancer patients, increased IL-6 serum levels were related to the presence of the tumor since all post-operative patients exhibited a marked decrease. In patients with advanced ovarian cancer post-operative levels of IL-6 correlated with residual disease. Very high levels of IL-6 were observed in the ascitic fluid of 9 ovarian cancer patients, but IL-6 mRNA was not detected in tumor cells. This suggests that the increased production of IL-6 observed in ovarian cancer is reactive. Higher levels of IL-6 were found in patients unresponsive to chemotherapy, as compared with responsive ones. Univariate analysis of survival data suggests that increased IL-6 serum levels correlate with negative prognosis.

Beta-thalassemia mutations in Rome. A high frequency of the IVSII-745 allele in subjects of latium origin

We studied the molecular bases of beta-thalassemia in Rome, a city centrally located in Latium, which is a region with a low incidence of beta-carriers. People also come to Rome from other regions for specific or prenatal diagnostic assessment. Only 11 patients (20%) out of 62 characterized beta-thalassemia subjects were of Latium family origin. They presented five mutations with an uncommonly high frequency of the IVSII-745 allele, that was found in homozygosis in 4 unrelated patients from a southeastern area in the province of Frosinone. These data may indicate a founder effect.

c-fes expression in ontogenetic development and hematopoietic differentiation

The c-fes protein (NCP92) is a tyrosine-specific protein kinase, capable of both autophosphorylation and phosphorylation of other substrates. We have analysed c-fes RNA expression in human/murine ontogenetic development and in homogeneous populations of embryonic and adult human hematopoietic cells. c-fes expression has been observed in rapidly proliferating embryonic-fetal tissues originating from different germinal layers, but not in adult non-hematopoietic tissues. In particular, a spatially and temporally regulated transcription was observed in the central nervous system and in developing cartilage. Expression in hematopoietic cells was evaluated in progenitors purified from embryonic-fetal liver and adult peripheral blood differentiating gradually and specifically along the erythroid or granulomonocytic lineage. In both embryonic and adult hematopoietic cells c-fes was abundantly expressed in undifferentiated progenitors of both lineages, as well as in differentiated granulomonocytic precursors, but not in erythroblasts. This expression pattern correlates with that of GM-CSF and in part IL-3 receptors (Testa et al., 1993 and our unpublished results). Altogether, these results suggest a possible role for c-fes in signal transduction, in both embryonic non-hematopoietic tissues and embryonic/adult hematopoietic cells, following interaction of growth factors with their tyrosine-kinase negative receptors (i.e., GM-CSF and IL-3 receptors in adult hematopoietic cells and other hypothetical growth factor(s) receptors during embryonic development.

High dose-intense chemotherapy alone or in combination with interleukin-2 for small cell lung cancer: a pilot study

Given the antitumor activity of interleukin-2 (IL-2) against some drug-resistant cancer cells, 17 previously untreated patients with small cell lung cancer entered a pilot study to evaluate the feasibility, efficacy, and immunological effects of combining 12-week high dose-intense chemotherapy based on a modified Evans regimen (CAV/PE) with different IL-2 schedules (6-12 MU/m2 week as a 48-72-h infusion using the same cumulative dose, 72 MU/m2). Despite significant myelotoxicity, up to 70% of the intended dose intensity was delivered, showing no differences with regard to the IL-2 schedule used. Immunotherapy-induced toxicity was usually mild and manageable. No limiting effects were observed in patients receiving immunotherapy except for a very poor compliance to the 12-week IL-2 regimen. The low-dose 72-h infusion was the optimal IL-2 schedule. As given in this study, neither of the alternating CAV/PE regimens abrogated the effects of IL-2 on T-cell and NK-cell subsets, showing typical kinetics with rebound in lymphocytes following each discontinuation of the IL-2. While immunological changes cannot predict the antitumor effect of IL-2, they are consistent with those described for IL-2 alone, suggesting its compatibility with high dose-intense chemotherapy. Although no definite advantages have been demonstrated in this small pilot study with significant unbalanced prognostic factors (12% 2-year survival), both the preserved immunostimulatory effects and the lack of limiting overlapping toxicity make this combined approach promising and worthy of further clinical investigation.

Mannoprotein-induced anti-U937 cell cytotoxicity in peripheral blood mononuclear cells from uninfected or HIV-infected subjects: role of interferon-gamma and tumor necrosis factor-alpha

A mannoprotein fraction (MP-F2: mannan, > 90%; protein, 4.5%) from the human commensal microorganism Candida albicans was as efficient as interleukin-2 (IL-2) in generating cytotoxicity against the uninfected or human immunodeficiency virus type-1 (HIV-1) persistently infected monocytoid U937 cell line in cultured peripheral blood mononuclear cells (PBMC) from healthy human subjects. MP-F2-activated killing of U937 cells (U937-MAK) decreased progressively with advancing stages of HIV-1 infection to virtually no killing effect in PBMC from advanced AIDS subjects (AIDS PBMC). This decrease paralleled a lowered susceptibility of U937 cells to natural killer cell activity. In contrast, IL-2-activated killing of U937 cells (U937-LAK) was not affected by the progression of HIV infection and persisted at high levels in AIDS PBMC. To shed light on the mechanisms of U937-MAK and its decrease during HIV infection, IL-1 beta, IL-6, TNF-alpha, GM-CSF, and IFN-gamma production was analyzed. Decreases in TNF-alpha, GM-CSF, and IFN-gamma, but not IL-1 beta or IL-6, levels were observed in MP-F2-stimulated PBMC from HIV-infected subjects, compared to healthy controls. Interestingly, these cytokine levels fell before the onset of AIDS. The greatest relative drop was that of IFN-gamma, from 4600 (+/- 600) to 290 (+/- 160) and 217 (+/- 110) mean pg/ml (+/- SE) in PBMC from healthy donors (11 subjects), CDC stages II + III (14 subjects), and CDC stage IV (10 subjects), respectively. The following observations suggest that decreased IFN-gamma production plays a role in the abrogation of U937-MAK activity: (i) addition of neutralizing anti-IFN-gamma antibodies abolished both IFN-gamma and U937-MAK activity in PBMC from healthy subjects; (ii) substantial levels of IFN-gamma were detected in supernatants of PBMC cultures stimulated by IL-2, in line with preserved U937-LAK activity. Interestingly, anti-IFN-gamma antibodies also abolished TNF-alpha production, and the anti-TNF-alpha antiserum effect was comparable to that of anti-IFN-gamma in U937-MAK inhibition. In contrast, anti-TNF-alpha antibodies abrogated TNF-alpha activity, but only partially reduced IFN-gamma production. Thus, in human PBMC, U937-MAK activity progressively decreases with advancing stages of HIV infection, whereas U937-LAK activity is sustained. Furthermore, the present results indicate a pivotal role for IFN-gamma in U937 MAK activity, possibly through activation of TNF-alpha production.

Stringently purified human hematopoietic progenitors/stem cells: analysis of cellular/molecular mechanisms underlying early hematopoiesis

Analysis of the cellular/molecular basis of the early steps of hematopoietic proliferation and differentiation is hindered by the rarity of hematopoietic progenitors and stem cells (HP/HSC). The intensive efforts devoted to the development of purification methods for early HP and HSC, although initially largely unsuccessful, have recently provided a high level of HP/HSC yield and/or recovery. The methodology developed by our group, recently improved, provides not only virtually complete purification, but also abundant recovery of early HP/HSC such as colony forming units granulocyte/erythroid/macrophage/megakaryocyte (CFU-GEMM), burst forming units erythroid (BFU-E), CFU granulocyte/macrophage (CFU-GM)/CFU blast cells (CFU-B), and long-term culture initiating cells (LTC-IC) from adult peripheral and cord blood (CB). We have also developed a serum-free liquid suspension culture for unilineage erythroid (E), granulocytic (G) or monocytic (M) differentiation of stringently purified HP/HSC. These culture systems allow sequential collection and cellular/molecular analysis of discrete populations of hematopoietic cells at a homogenous stage of differentiation specifically along a unilineage pathway. These experimental tools have been utilized to investigate cellular/molecular mechanisms underlying early hematopoiesis. The transcription factor (TF) GATA-1 is considered to be the "master" gene of erythropoiesis. In highly purified HP/HSC undergoing E or GM differentiation, GATA-1 expression is characterized initially by proliferation-dependent activation and at later stages by sustained expression in the E pathway and suppression in the GM pathway. Hypothetically, similar on/off switches of lineage-restricted TF may underlie the binary fate decisions of early HP differentiation. The expression and modulation of hematopoietic growth factor receptors (HGFR) in early hematopoiesis have been extensively analyzed. The results suggest a model of transactivation cascade for HGFR such as interleukin 6 receptor (IL-6R), IL-3R, GM colony stimulating factor receptor (GM-CSFR), and erythropoietin receptor (EpR), whereby each HGF upmodulates the R(s) for distal-acting HGF(s). Finally, we have investigated the effect of HGF on reactivation of hemoglobin F (HbF) in clonogenic or liquid suspension serum-free culture of purified adult HP. The results suggest that c-kit ligand (KL) plays a key role in the reactivation of HbF synthesis in adult life, and IL-3/GM-CSF potentiate this effect at low KL level. The KL-induced HbF reactivation is seemingly related to an enhanced proliferation of early E progenitors in their differentiation pathway.

The acute promyelocytic leukemia-specific PML-RAR alpha fusion protein inhibits differentiation and promotes survival of myeloid precursor cells

Acute promyelocytic leukemia is a clonal expansion of hematopoietic precursors blocked at the promyelocytic stage. The differentiation block can be reversed by retinoic acid, which induces blast maturation both in vitro and in vivo. Acute promyelocytic leukemia is characterized by a 15;17 chromosome translocation with breakpoints within the retinoic acid alpha receptor (RAR alpha) gene on 17 and the PML gene, which encodes a putative transcription factor, on 15. A PML-RAR alpha fusion protein is formed as a consequence of the translocation. We expressed the PML-RAR alpha protein in U937 myeloid precursor cells and showed that they lost the capacity to differentiate under the action of different stimuli (vitamin D3 and transforming growth factor beta 1), acquired enhanced sensitivity to retinoic acid, and exhibited a higher growth rate consequent to diminished apoptotic cell death. These results provide evidence of biological activity of PML-RAR alpha and recapitulate critical features of the promyelocytic leukemia phenotype.

Replication and multiplication of hepatitis C virus genome in human foetal liver cells

The ability to obtain primary long-term cultures of human foetal hepatocytes maintaining liver differentiation characteristics in serum-free medium prompted us to test their susceptibility to hepatitis C virus infection. Using PCR, we detected the presence of the HCV RNA-positive strand in the supernatants and in the cells of the virus-infected hepatocyte cultures, at various times post-infection. Evidence of effective virus genome replication and multiplication was also based on the time-dependent appearance of the putative HCV RNA-negative strand, the detection of virus replicative intermediates and an increase in HCV genomic templates in the HCV-infected cells.