Search

Repeated analysis of peripheral blood lymphocytes (PBLs) from a patient with large granular lymphocytosis, neutropenia, and rheumatoid arthritis revealed that approximately 45% of PBLs displayed the following phenotype: CD3+, CD4-, CD8-, CD16+, HNK-1-, WT31-. This population was purified for further analysis by depletion with anti-CD4 and anti-CD8 monoclonal antibodies (MoAbs). Southern blot analysis showed preferential rearrangements of the V gamma 9 genes. Northern blot demonstrated the presence of V gamma 9 mRNA transcripts. With MoAbs directed against either the V gamma 9 peptide (Ti gamma A) or the delta chain of the gamma delta T-cell receptor (TCR delta 1), we further demonstrated that those cell surfaces expressed both V gamma 9 and a delta gene product. In addition, analysis of the gamma gene rearrangements on six clones derived from this population demonstrated a unique rearrangement on a single chromosome, strongly suggesting the monoclonality of this T-cell population. Significant cytotoxic activity against K562, U937 was observed only after an in vitro culture period with interleukin-2 (IL-2), whereas no specific inhibitory effect on autologous bone marrow (BM) CFU-G was noted.

Allogeneic bone marrow transplantation is still limited by the morbidity and mortality caused by graft-versus-host disease (GVHD), resulting from host recognition by donor T lymphocytes. It is possible to drastically reduce the T-cell content of the graft. However, transplanted T cells can also have a beneficial effect by graft enhancement and the graft-versus-leukemia effect. How can we keep the beneficial GVL effect while protecting the patient from possible GVHD? A recent report proposed the ex vivo transfer of the herpes simplex thymidine kinase (HSv-tk) gene into donor T cells before their infusion with hematopoietic stem cells. This procedure is expected to allow selective donor T-cell depletion with ganciclovir should GVHD occur, but it has two major drawbacks: reinjection of a fraction of untransfected T cells cannot be avoided and heterogeneity of the transfected population results in increased risks such as HSv-tk gene instability or dysfunction of some of the transfected T cell. Alternative approaches must be considered. We demonstrate here the feasibility of generating HSv-tk transfected HLA-specific CD4+ cytotoxic T-cell clonal populations, in which 100% of the cells have the HSv-tk gene inserted at a single site within their genome. These clones retained their specificity, their function, and their sensitivity to ganciclovir treatment. Our approach is not limited to bone marrow transplantation. Indeed, this procedure represents a useful alternative to retroviral gene transduction and is applicable to every circumstance where clinical use of gene modified T-cell clones is to be considered.

The erythropoietin receptor (EPO-R) can be activated to signal cell growth by binding either EPO or gp55, the Friend spleen focus-forming virus (SFFV) glycoprotein. EPO binding induces tyrosine kinase activity and rapid tyrosine phosphorylation of several cellular substrates. To test for gp55-induced tyrosine kinase activity, we performed immunoblots on two murine cell lines that stably express EPO-R and gp55. Stimulation of the parental cell line, Ba/F3, with murine interleukin-3 (IL-3) resulted in rapid, dose-dependent tyrosine phosphorylation of a 97-Kd substrate. Stimulation with IL-3 or EPO of the Ba/F3 cells expressing the recombinant EPO-R (Ba/F3-EPO-R) resulted in tyrosine phosphorylation of the same p97 substrate. These latter cells, when transformed to growth factor-independence by the Friend gp55 glycoprotein, exhibited constitutive tyrosine phosphorylation of the 97-Kd substrate. Other growth factor-independent Ba/F3 subclones, transformed with either the oncoprotein, v-abl, or with a constitutively activated EPO-R, also had constitutive phosphorylation of a 97-Kd substrate. In CTLL-2-EPO-R cells, a T-lymphocyte line stably transfected with the EPO-R, the 97-Kd substrate was tyrosine- phosphorylated in response to IL-2 or EPO. The 97-Kd protein was constitutively phosphorylated in CTLL-2-EPO-R-gp55 cells. In conclusion, a 97-Kd protein found in two murine cell lines is tyrosine-phosphorylated in response to multiple growth factors and viral oncoproteins, and appears to be a central phosphoprotein in signal transduction.

We have a previously reported that interleukin-10 (IL-10) is a potent but IL-6-unrelated growth factor for freshly explanted myeloma cells (Lu et al, Blood 85:2521, 1995). We have also shown that exogenous IL-10 supported the growth of XG-1 and XG-2 human myeloma cell lines (HMCL) through an IL-6-independent mechanism. (Lu et al, Blood 85:2521, 1995). Because the IL-10 receptor does not involve the gp 130 IL-6 transducer, we have attempted to elucidate the mechanisms of IL-10 action on myeloma cells. Our results indicate that the myeloma cell growth factor activity of IL-10 was abrogated by an antibody to the gp 130 IL-6 transducer, indicating that it was mediated through one of the gp 130-activating cytokines. We found that myeloma cells from XG-1 and XG-2 HMCL and from 5 of 6 patients' tumoral samples produced oncostatin M (OM) constitutively but failed to produce IL-6, IL-11 and leukemia- inhibitory factor (LIF). The autocrine OM was inactive in the absence of IL-10 due to lack of a functional OM receptor on myeloma cells. IL- 10, by inducing the receptor for LIF (LIFR), produced a functional autocrine OM loop in XG-1 and XG-2 cells and in primary myeloma cells from 2 patients. We also found that some myeloma cell lines (XG-4, XG- 6, and XG-7) an fresh myeloma cells from 3 of 6 patients produced an autocrine IL-10 and that these cells constitutively expressed LIFR. One HMCL (XG-7) produced IL-10, OM, and IL-6 an expressed LIFR. The XG-7 cells used OM and IL-6 as autocrine growth factors. We have previously shown that IL-10 could induce IL-11 receptor in myeloma cells and confer on them sensitivity to IL-11 (Lu et al, FEBS Lett 377:515, 1995). Taken together, these results show that IL-10 is a key cytokine for inducing the expression of LIFR and IL-11R and possibly another uncharacterized OM coreceptor on myeloma cells and that OM and IL-10 might be produced by myeloma cells. They also emphasize that all myeloma cell growth factors reported to data involve an activation of the gp130 IL-6 transducer.

We previously described a lymphokine termed HILDA (for human interleukin DA) produced by T-lymphocyte alloreactive clones after antigenic stimulation. This factor sustains the growth of a murine IL3- sensitive cell line (DA2). In addition, HILDA is a potent activator of eosinophils and displays a burst-promoting activity on human bone marrow. In the present study, HILDA was purified to homogeneity from T- cell clone supernatant using successively sequential concentration, concanavalin A (ConA) affinity chromatography with differential elution (alpha-D glucopyranoside and alpha-D mannopyranoside), high-performance liquid chromatography (HPLC) gel filtration and reverse-phase HPLC. The pure material appeared as a 38-kd glycoprotein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing or nonreducing conditions. Biologic activity could be recovered from SDS- PAGE gel slices corresponding to the 38-kd band. We conclude from the specificity of the DA-2 cell line and biochemical characteristics described that this lymphokine is different from other known factors produced by human T lymphocytes.

Endothelial cell (EC) may represent a major source of cytokines in the bone marrow. In this study we have examined the production and the regulation of the production of leukemia inhibitory factor/human interleukin for DA cells (LIF/HILDA) by EC. Human umbilical vein endothelial cells (HUVEC) were chosen as a working model as they are a well known source of cytokines. These cells secrete LIF/HILDA (90 pg/mL/10(6) cells/48 h) in basal conditions. This secretion is profoundly altered by interleukin-1 alpha (IL-1 alpha). Secretion of LIF/HILDA is increased threefold on stimulation with IL-1 alpha at a concentration of 100 IU/mL. The secreted protein is bioactive as demonstrated by its proliferative effects on DA1a cells. Modulation of the production of LIF/HILDA by glucocorticoids (GC) was also examined. In striking contrast to what was observed for IL-1 alpha, the synthetic GC dexamethasone (DXM) at a concentration of 10(-6) mol/L consistently inhibited the basal secretion of LIF/HILDA by an average of threefold and suppressed the IL-1 alpha-induced increase of the secretion of this cytokine by HUVEC. In an effort to extend results obtained with HUVEC to the bone marrow endothelium, we have also examined the production of LIF/HILDA by human bone marrow endothelial cells (HBMEC). Our study shows that HBMEC are quantitatively a very important source of this cytokine (above 7.25 ng/mL/10(6) cells/48 h) suggesting that they are a major source of LIF/HILDA in the bone marrow. Again, IL-1 alpha proved to be a very potent stimulus for the secretion of LIF/HILDA and synthetic GC such as DXM when used at a concentration of 10(-6) mol/L inhibited by an average of threefold the basal secretion of LIF/HILDA and had suppressive effect on the IL-1 alpha-induced increase of this secretion. The downregulation of LIF/HILDA production in the bone marrow by GC may be important to understand the effects of GC on hematopoiesis.

Macrophage colony stimulating factor (CSF-1) is one of several cytokines that control the differentiation, survival, and proliferation of monocytes and macrophages. A set of 11 human T-cell clones, chosen for their phenotypic diversity, were tested for their ability to express CSF-1 mRNA. After 5 hours of stimulation with phorbol myristate acetate (PMA) + calcium ionophore (Cal), all T-cell clones expressed a major 4-kb transcript, a less abundant 2-kb transcript, and several other minor species. This pattern of expression is typical for CSF-1 mRNAs. Furthermore, of the two alloreactive T-cell clones analyzed, only one showed a definitive message for CSF-1 on specific antigenic stimulation, but with delayed kinetics and less efficiency. Both conditions of stimulation induced the release of CSF-1 protein by T cells in the culture medium. Together, these findings demonstrate for the first time that normal T cells are able to produce CSF-1, previous reports being limited to two cases of tumoral cells of the T-cell lineage.

Interleukin-11 (IL-11) is a stromal cell-derived cytokine with multiple biologic activities on lymphohematopoietic cells. It belongs to a family of pleiotropic and redundant cytokines that use the gp 130 transducing subunit in their high affinity receptors. By amplifying human cDNA libraries with oligonucleotide primers corresponding to the conserved WSXWS motif found in the hematopoietic cytokine receptor family, a novel cytokine receptor cDNA was identified that, based on high (82%) sequence homology with the recently cloned murine IL-11 receptor, appears to encode the human IL-11 receptor. This receptor is a 422-amino acid protein containing a signal peptide followed by extracellular, transmembrane, and cytoplasmic domains. The extracellular region has a two-domain structure homologous to those of the IL-6 and ciliary neurotrophic factor (CNTF) receptors: an immunoglobulin-like domain and a cytokine receptor-like domain. In addition, an isoform of the human IL-11 receptor that lacks the cytoplasmic domain was also identified. In agreement with the pleiotropic effects of IL-11 on different hematopoietic lineages and bone cells, IL-11 receptor transcripts were found to be expressed by the myelogenous leukemia cell line K562, the megakaryocytic leukemia cell line Mo7E, the erythroleukemia cell line TF1, and the osteosarcoma cell lines MG-63 and Saos-2.

Human cytomegalovirus (CMV) infection is often associated with myelosuppression and acute inflammatory reaction in immunocompromised patients. We have previously documented that CMV exposure of bone marrow (BM) stromal cells reduces the capacity of these cells to support hematopoiesis because of a decreased production of colony- stimulating factors. This study examines the potential role of CMV on constitutive and lipopolysaccharide (LPS)-stimulated production of cytokines involved in inflammatory reaction, interleukin-6 (IL-6) and leukemia inhibitory factor (LIF) by BM stromal cells. The release of IL- 6 was already detectable 2 hours post CMV-infection (2.5-fold increase in production) and the cumulative production of IL-6 after 5 days of infection was 23 +/- 1.2 ng/mL (ninefold increase in production). CMV was also able to induce a time-dependent production of LIF that was maximal 8 hours after CMV infection (2.5-fold increase in production). Concomitantly, there was no detectable release of granulocyte colony- stimulating factor (G-CSF) and granulocyte-macrophage CSF (GM-CSF) by CMV-infected stromal cells. The similar IL-6 and LIF production in the presence of polymyxin B ruled out the possibility that this increase could be caused by contamination of the viral stock by endotoxin. In addition, ultraviolet-inactivated virus behaved similarly to live virus and caused the release of IL-6 and LIF. However, heat-inactivated CMV was unable to induce IL-6 and LIF secretion by BM stromal cells. The production of IL-6 and LIF was also evaluated after stimulation by LPS. After 5 days of CMV exposure, the LPS-stimulated production of IL-6 and LIF was significantly lower than uninfected controls. This LPS-induced release of cytokine production was found to be dependent of viral replication. The experiments have shown that CMV is a potent inducer of IL-6 and LIF with differential effect on constitutive and LPS- stimulated cytokine production by stromal cells; we suggest that CMV induction of IL-6 and LIF during the first hours of infection could play a role in CMV-induced inflammatory reaction. Moreover, our results show that human CMV can disturb the balanced cytokine network involved in the regulation of hematopoiesis.