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H Brailly

Publications and source records attributed to H Brailly.

32 records · Page 2Linked to original sources
PubMed1993

The CD2 and CD28 adhesion molecules induce long-term autocrine proliferation of CD4+ T cells.

In vitro human T lymphocyte activation requires two-signal triggering delivered by lectins, phorbol esters or antibodies directed against surface molecules. Stimulation of adhesion molecules by CD2 and/or CD28 antibodies defines alternative activation pathways. Activation by CD2 + CD28 monoclonal antibodies induces high-level, long-lasting and monocyte-independent proliferation of highly purified T cells. Limiting dilution cultures showed that CD28 in association with CD2 or CD3, without addition of exogenous cytokines, induced single-cell proliferation. CD2 + CD28 stimulation induced long-term interleukin (IL)-2-dependent autocrine proliferation of CD4+ T cell clones. We tried to elucidate this long-term proliferation by evaluating cytokine secretion and cytokine dependency. CD28 associated to CD3 or CD2 induced high levels of IL-2, tumor necrosis factor (TNF) and IL-4 secretion for 10 days, in contrast to CD3 alone which induced only TNF secretion. Cytokines of the monocytic lineage were also secreted, such as colony-stimulating factor-1, granulocyte-macrophage colony-stimulating factor or IL-1, the latter being more specific of CD2 + CD28 activation. Blocking antibodies confirmed the crucial role of IL-2 in CD2 + CD28 activation. Anti-IL-4, anti-IL-7 receptor or anti-TNF antibodies had no effect on proliferation. Stimulation with CD2 + CD28 induced long-term autocrine (at least for IL-2) proliferation for CD4+ T cells, with no evidence for the implication of another cytokine among those tested other than IL-2. This represents a model for long-term autocrine growth for non-leukemic cells.

Antigens, CD↗
PubMed1993

Increased and highly stable levels of functional soluble interleukin-6 receptor in sera of patients with monoclonal gammopathy.

Soluble human interleukin-6 receptor (sIL-6R) was measured in the serum of 30 healthy individuals, 32 individuals with monoclonal gammopathy of undetermined significance (MGUS), 20 patients with early multiple myeloma (MM) and 54 patients with overt MM. The serum activity recognized by an immunoradiometric assay was determined to be sIL-6R, because of its binding capacity to IL-6 and its molecular mass of 55 kDa. All sera of healthy individuals contained sIL-6R (mean value: 89 ng/ml, range 17-300 ng/ml). Serum sIL-6R levels were increased by 51% in patients with MGUS (mean value: 135 ng/ml, p < 0.005), by 44% in patients with early myeloma (mean value: 128 ng/ml, p < 0.001) and by 116% in patients with overt MM (mean value: 193 ng/ml, p < 0.001). In patients with MM, a complete lack of correlation (p > 0.7) was found between serum sIL-6R levels and other previously recognized prognostic factors in this disease, particularly serum IL-6 levels and those factors related to tumor cell mass. The independence of serum sIL-6R levels on tumor cell mass was directly demonstrated by studying four patients with MM treated with autologous bone marrow transplantation for periods of between 320 and 760 days. These levels were found to be remarkably stable and constant, independent of whether patients relapsed or achieved complete remission. Finally, physiological concentrations of sIL-6R were found to increase by tenfold the sensitivity of human myeloma cell lines to IL-6. These observations suggest a high control of the sIL-6R level in vivo, and, possibly, an important functional role of this circulating protein in patients with monoclonal gammopathies.

Female↗
PubMed1993

Overall interleukin-6 production exceeds 7 mg/day in multiple myeloma complicated by sepsis.

We previously reported that injection of anti-IL-6 monoclonal antibody (mAb) in a patient with multiple myeloma (MM) induced the circulation of high amounts of IL-6 in the form of IL-6/anti-IL-6 monomeric complexes. This made it possible to estimate overall daily IL-6 production in patients in vivo, which had not been achieved in animals or humans before. In this study, estimations are given for a patient with MM who developed Escherichia coli sepsis during anti-IL-6 mAb. During the first 12 days, the overall IL-6 production was estimated at 1.5 to 2.0 micrograms/day. On day 13, serum IL-6 concentration, in the form of IL-6/anti-IL-6 complexes, increased 1000-fold and was 1.7 x 10(6) pg/ml, in relation with the development of E. coli sepsis. Overall IL-6 production was estimated to be greater than 7 mg/day, i.e. 3500 times higher than before sepsis. Serum IL-6 levels in the form of monomeric immune complexes remained very high for 20 days after sepsis indicating the persistence of very high overall IL-6 production (100 to 3500-fold greater than pre-sepsis production). This study demonstrates a considerable and persistent potential for IL-6 production in this patient during and after sepsis.

Antibodies, Monoclonal↗
PubMed1993

Targeting of interleukin-2 to the periplasm of Escherichia coli.

A synthetic gene coding for interleukin-2 (IL-2) was used to produce large amounts of recombinant IL-2 (met-IL-2) in Escherichia coli. Met-IL-2 was found to accumulate in the cytoplasm in an insoluble, aggregated form. Inclusion bodies located at the pole caps of cells were detected using immunogold labelling. Constructs were designed to fuse the IL-2 gene to DNA fragments encoding signal peptides for an outer-membrane protein (OmpA) or for a periplasmic protein (PhoA) of E. coli. No significant maturation was observed with these fusion proteins which were found in an insoluble form in the cytoplasm. The influence of charge disposition at the N-terminus of the mature portion of the protein was investigated by replacing positively charged amino acids with glutamic acid. None of the introduced substitutions had any effect. Various factors that might affect expression, secretion and folding were examined in an attempt to obtain secretion. By fusing IL-2 to the precursor maltose-binding protein (preMBP) a large fraction of the preMBP-IL-2 protein was correctly processed and transported to the periplasmic space. IL-2 derived from MBP-IL-2 after FXa cleavage possessed similar specific activity to recombinant IL-2 produced in Chinese Hamster ovary cells.

Amino Acid Sequence↗
PubMed1993

Interleukin-7 is a potent co-stimulus of the adhesion pathway involving CD2 and CD28 molecules.

Co-stimulation of highly purified peripheral T lymphocytes from healthy blood donors with the adhesion molecules CD2 and CD28 in association with recombinant interleukin-7 (rIL-7) induced T-cell proliferation, multiple cytokine secretion and IL-2 receptivity. We demonstrated that rIL-7 is as potent as rIL-2 in inducing the proliferation of unseparated, CD4+ and CD8+ T cells. In contrast to low or undetectable levels of IL-1 alpha, IL-6 and IL-2, high levels of tumour necrosis factor-alpha (TNF-alpha), IL-4 and granulocyte-macrophage colony-stimulating factor (GM-CSF) were secreted. Experiments using blocking antibodies suggested a direct mechanism for rIL-7 co-stimulatory effect, although induction of the CD25/IL-2 receptor alpha-chain (CD25/IL-2R alpha) was observed. Monoclonal antibodies (mAb) against the adhesion molecules CD2 and CD28 are likely to mimic the interaction with their respective physiological ligands [lymphocyte function-associated antigen-3 (LFA-3)/CD58, CD59 and CD48 for CD2, B7/BB1 for CD28]. Taken together, these in vitro data suggest that IL-7 could participate in paracrine interactions between T lymphocytes and thymic stromal cells or dendritic cells, via its potent co-stimulatory activity with CD2 and CD28 adhesion molecules.

Antigens, CD↗
PubMed1993

TNF alpha acts in synergy with GM-CSF to induce proliferation of acute myeloid leukemia cells by up-regulating the GM-CSF receptor and GM-CSF gene expression.

Acute myeloid leukemia (AML) cells are dependent for their survival and proliferation on hematopoietic growth factors. As tumor necrosis factor alpha (TNF alpha) can increase the proliferation of primary cultures of AML cells, we have investigated the effect of TNF alpha on the autocrine and/or paracrine growth control by one of the major AML growth factor, granulocyte-macrophage colony-stimulating factor (GM-CSF). First, a panel of AML cells were analysed with respect to their proliferative response to TNF alpha. We provide experimental evidence that TNF alpha induces both GM-CSF gene expression and up-regulation of high-affinity GM-CSF membrane receptor in TNF alpha-responsive cells. This effect is not restricted to the malignant phenotype, although it could account for the selective growth advantage of the leukemic clone over the normal cells upon TNF alpha stimulation.

Acute Disease↗
PubMed1992

Prolonged IL-2 receptor alpha/CD25 expression after T cell activation via the adhesion molecules CD2 and CD28. Demonstration of combined transcriptional and post-transcriptional regulation.

The T cell adhesion molecule CD28 provides a costimulatory signal in combination with CD2 and CD3 mAb. CD28 regulates the expression of cytokines by T cells, not only IL-2, but also IL-1 alpha and CSF-1, usually synthesized by accessory cells. We have investigated the mechanisms through which CD28 modulates the expression of the IL-2R alpha chain. Whereas activation through CD2 or CD28 alone induced no or only low IL-2R alpha chain expression, activation through CD2 plus CD28 led to both a high and prolonged (greater than 14 days) cell surface and mRNA expression. In contrast, immobilized CD3 mAb-dependent activation induced a transient expression of the IL-2R alpha chain, which was neither further increased nor prolonged by CD28 costimulation. Upon CD2 plus CD28 stimulation, the half-lives of the two IL-2R alpha transcripts increased progressively between days 1 and 4, in contrast to each pathway alone. Whereas each activation pathway alone induced either no (CD2) or low (CD28) levels of IL-2R alpha gene transcription, the CD2 plus CD28 stimulation was associated with its increased transcription, which persisted at similar rates between 5 and 96 h post stimulation. The in vitro costimulation via the CD2 and CD28 molecules thus regulates the expression of the IL-2R alpha gene both at the transcriptional and post transcriptional levels. Our results therefore demonstrate a new immunoregulatory function of the CD28 molecule on IL-2R alpha expression, which, through its increased transcription rate and stabilization, could, together with high levels of cytokines secretion, be responsible for the prolonged T cell proliferation.

Antigens, CD↗
PubMed1992

High amounts of circulating interleukin (IL)-6 in the form of monomeric immune complexes during anti-IL-6 therapy. Towards a new methodology for measuring overall cytokine production in human in vivo.

A patient with plasma cell leukemia was treated with anti-interleukin (IL)-6 monoclonal antibodies (mAb) for 2 months. Using chromatography on protein A-Sepharose, anti-murine-IgG-Sepharose, anti-IL-6-mAb-Sepharose and gel filtration at pH 2.3, we have demonstrated that the anti-IL-6 mAb, by preventing the binding of IL-6 to its cell membrane receptor and its renal elimination, has induced huge amounts of IL-6 to circulate in the form of monomeric immune complexes. By using this observation, we have developed a mathematical modelling that allows the determination of the overall daily production of IL-6 in this patient, which was in the range of 15 micrograms per day. Overall in vivo production of cytokines has never been evaluated in animals or in humans before.

Antibodies, Monoclonal↗
PubMed1991

IL-1 alpha is produced by T lymphocytes activated via the CD2 plus CD28 pathways.

In addition to activation via the TCR complex, resting purified T cells can be activated to proliferate by mAb directed against the two surface molecules, CD2 and CD28. We demonstrate here that only the CD2 plus CD28 combined activation induces the expression and secretion of IL-1 alpha, a cytokine classically considered as a monokine. In contrast, neither IL-1 beta nor IL-6 were produced. A second monokine, TNF-alpha was transiently expressed by T cells activated with either CD2 or CD28 mAb, but was expressed to higher levels and with a prolonged kinetics in cells activated by the CD2 plus CD28 combination. The prolonged expression of the IL-1 alpha gene could account, at least in part, for the monocyte-independent and long lasting T cell proliferation induced by the CD2 plus CD28 co-stimulation. Secretion of monokines, such as IL-1 alpha, by activated T cells, could play a regulatory role in immune responses, as well as contribute to autoimmune processes.

Antigens, CD↗
PubMed1988

Elimination of leukemia cells from human bone marrow using floating beads.

A new in vitro immunophysical method of removing leukemia or lymphoma cells from autologous bone marrow is described. This new technique makes use of low-density polypropylene beads (density: 0.91) coated with a monoclonal antibody anti-CALLA (antibody ALB2). To ascertain its ability to selectively remove human B/pre-B hematopoietic cells, this technique was applied to normal human bone marrow cell suspensions contaminated with 1-5% of tumor cells. Samples were incubated with the floating beads at 4 degrees C on a rotating wheel for 60 min, followed by a 10-min decantation period, after which the beads bearing the tumor cells floated on the surface, whereas unbound normal marrow cells remained in suspension and were easily recovered free of beads. To demonstrate the feasibility of our method, 2 types of assays were carried out, one using target cell radiolabeled with 111indium, and the other a clonogenic assay. The first assays were to calibrate the different parameters (cellular density, quantity of beads, incubation time) with tumor cell lines: Namalwa (CALLA+) and Molt 4 (CALLA-). These 2 cells lines being able to clone, it is hard to envisage clonogenic assays. In this case, it is very hazardous to evaluate correctly the remaining clonogenic units of Namalwa cells. It is why radiolabelling assays were used for these first experiments. The second assays were to study a model close to the clinical setting and to control the safety of the beads on normal bone marrow cells. In this case, the mixture experiments in which only Namalwa cells were able to clone were evaluated with clonogenic assays, which are more sensitive than radiolabeling assays. A 3- to 4-log reduction of tumor load was achieved with 1-step treatment, and an average of 5-log depletion was obtained by repeating the process twice, as ascertained by the clonogenic assay. Viability, average recovery of nucleated cells, and stem cells potential following the purge were excellent.

Antibodies, Monoclonal↗
PubMed1988

[Processing of clonogenic findings in limited dilution. Application to the quantification of autograft depletion].

Limiting dilution culture is a powerful tool for the quantification of residual clonogenic cells in the evaluation of a depletion procedure in bone marrow purging. The definition of suitable numerical indicators and the choice of the statistical technique for data treatment are of crucial importance. Most common techniques are presented and discussed. A standardization for data treatment is proposed.

Bone Marrow Cells↗
PubMedDate not supplied

Epitope analysis of human IL-6 receptor gp80 molecule with monoclonal antibodies.

Gp80 human IL-6R was studied using 7 murine mAb (M37, M91, M113, M139, M164, M182 and M195) obtained after fusion of splenocytes of Balb/c mice immunised with a mixture of recombinant IL-6 receptor (rIL-6R) and cells from 2 cell lines expressing IL-6R. These were U266, which is IL-6 independent and XG-1 which is IL-6-dependent. In ELISA the 7 mAb reacted against the rIL-6R and against the natural soluble form found in plasma (nIL-6R), which both lack transmembrane and cytoplasmic domains. However, M195 reacted less with the natural than with the recombinant soluble IL-6R. Using FACS analysis, the 7 mAb were shown to bind to U266 cells but not to the Namalva cell line which is deprived of IL-6R. This showed that they all recognised the membrane form of the IL-6R. Three of the anti-IL-6R mAb reacted with rIL-6R by Western blotting. Four different epitopes of the molecule were identified, either by cross-blocking experiments of mAb binding to IL6R in ELISA or by the biosensor Biacore technology. A group of 4 mAb (M37, M113, M139 and M164) and another mAb (M195) identified 2 different epitopes involved in IL-6 binding. These antibodies were able to inhibit the binding of IL-6 to IL-6R and the proliferation of the IL-6-dependent XG-1 cell line. M91 and M182 recognized 2 other epitopes that were not involved in IL-6 binding. As expected, M91 did not inhibit XG-1 proliferation; in contrast, M182 interfered with the proliferative response of the XG-1 cell line.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗