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S Huet

Publications and source records attributed to S Huet.

At least 37 records · Page 2Linked to original sources
PubMed1997

Measuring multidrug resistance expression in human malignancies: elaboration of consensus recommendations.

Before the prognostic significance of P-glycoprotein (P-gp) expression can be properly evaluated in prospective clinical trials of P-gp modulators, standard techniques for the measurement of P-gp must be widely accepted. Several multicenter trials have demonstrated large discrepancies in the observed levels of P-gp expression in the same clinical samples evaluated at different centers. The greatest discrepancies occurred with samples that expressed low levels of P-gp. Although standardized procedures have dramatically increased the interlaboratory reproducibility of flow cytometry and polymerase chain reaction assays, data from immunocytochemistry remain difficult to interpret. Consensus recommendations are presented for improving data reproducibility. These recommendations emphasize the importance of using calibrated batches of antibodies and two different antibodies for immunocytochemistry, the need for an internal standard for reverse transcriptase-polymerase chain reaction (RT-PCR) assays, the need for the presentation of data as a continuous variable, and the need for setting standard parameters for flow cytometry. It is also extremely important for the success of clinical trials that multiple techniques be employed to insure accurate measurement of P-gp expression.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

A phase I trial of repeated tumour-infiltrating lymphocyte (TIL) infusion in metastatic melanoma.

The aim of the protocol was to evaluate the side-effects induced by repeated tumour-infiltrating lymphocyte (TIL) infusions in patients with metastatic melanoma (MM). Patients were to receive four TIL infusions at given intervals: every 3 weeks (two patients), every 2 weeks (3 patients) and weekly (4 patients). All patients were evaluated and received a total of 34 TIL infusions. The total number of TILs administered varied from 0.65 to 2.34 x 10(11) cells. TIL phenotypes were predominantly CD8+ (two patients), CD4+ (4 patients), CD4+ then CD8+ (two patients) or CD56+ (two patient). Autocytotoxicity was only observed for one culture. Six patients presented at least one WHO grade 3 side-effect: hypotension (5 patients), dyspnoea (two patients), fever (one patient), fatigue (one patient), chills (two patients), diarrhoea (one patient), agitation (one patient), locoregional pain (two patients). Hypotension was constantly seen in patients who were given TILs every week. Two cases of minor pericarditis were recorded. No objective response to treatment was observed; 1 stable disease occurred in one patient and progression in eight. However, five patients presented a partial response on a tumour site for 1-4 months. Three patients presented signs of inflammation or softening at one tumour site. Plasma tumour necrosis factor alpha (TNF-alpha) levels were increased 1.2- to 22-fold after TIL infusion. TILs could be produced in sufficient quantity to perform this study, so repetitive infusions of TIL became possible on a weekly basis. However, no objective response was observed even when TIL infusions were performed weekly. An increase in circulating TNF-alpha was noted after TIL infusion.

Adolescent↗
PubMed1995

Human liver-associated lymphocytes: an overview.

Morphological and phenotypical data indicate that liver sinusoids contain a heterogeneous population of lymphocytes of which large granular lymphocytes are only one element. It is suggested that the term of liver-associated lymphocytes (LAL), which encompasses all sinusoidal lymphocytes, be used for this fourth sinusoidal cell type. Studies realized by flow cytometry on isolated cells have shown that human LAL differ phenotypically from peripheral blood lymphocytes (PBL). LAL are characterized by a three-fold increase in the percentage of cells presenting the CD56 antigen, a natural killer (NK) marker, but also an increase in the percentage of CD8 cells and a decrease in the percentage of CD4. Furthermore, within the CD56+ LAL population, 95% of cells are CD3+/- CD16-, whereas the majority of CD56+ cells in PBL are CD3-/CD16+. These differences do not seem to depend on liver pathology since no differences were found in the LAL phenotype, for all markers analysed, between patients with liver metastasis or with benign liver tumours. Liver sinusoids also harbour T cells bearing the gamma/delta chains with a repertoire of V gene arrangements which differs from that found in PBL from the same patients, confirming a site-specificity. Functionally, LAL were shown to possess a higher level of NK cell activity against K-562 cells than PBL. LAL also expressed a lymphokine activated killer (LAK) activity against NK-resistant cell lines (Raji cells), whereas no such activity was detected in PBL from the same patients. Interestingly, LAK-activity from LAL isolated from patients with liver metastases was dramatically decreased compared to that from LAL isolated from patients with benign liver disease. The level of LAK activity of LAL situated distant to the malignant tumour was higher than that obtained from LAL close to the tumour, thus suggesting that cytotoxic lymphocyte capabilities could be inhibited by tumoral cells. LAL differ, both quantitatively and qualitatively, from PBL in the expression of cellular adhesion molecules. Precise mechanisms of their homing or in situ differentiation must still be elucidated.

Cytotoxicity, Immunologic↗
PubMed1994

Detection of cell-adhesion molecules on human liver-associated lymphocytes.

Liver-associated lymphocytes (LAL) from human liver are phenotypically and functionally different from peripheral blood lymphocytes (PBL). Phenotypically, they are mainly represented by the CD3+/-CD56+ phenotype and functionally they spontaneously possess lymphokine-activated killer (LAK) activity. In this study we evaluated the expression of cell-adhesion molecules (CAM) which could be involved in LAL contacts with other sinusoidal cells and/or be responsible for the LAK activity. The LAL population was isolated by sinusoidal high-pressure lavage from partial hepatectomies obtained from patients operated on for benign liver disease (n = 6). Surface expression of the beta 2 integrin chains (CD18, CD11a, CD11b, CD11c), as well as that of members of the immunoglobulin superfamily (CD2, CD54, CD56, CD58), were analysed by one or two-colour flow cytometry. Quantitative and qualitative differences were observed in the expression of CAM between LAL and PBL. LAL were characterized by an increase in the percentages of CD11b+, CD54+, CD56+ and CD58+ cells and a decrease in the percentage of CD2+ cells compared to PBL. Fluorescence intensity values for CD2 and CD56 were higher in LAL than in PBL. Moreover, CD11a/CD18 cells presented a bimodal distribution (dim and bright) in both PBL and LAL; whereas these two subpopulations were equally represented in PBL, the number of bright cells was significantly greater (> 80%) in LAL. The increase in CAM expression (percentage of positive cells and intensity of fluorescence) on LAL combined with their increase in natural killer (NK) and LAK activities already reported, support the idea that, at least some, LAL might be, compared to PBL, in an activated state in vivo.

Antigens, CD↗
PubMed1993

Pharmacological and molecular characterization of intrinsic and acquired doxorubicin resistance in murine tumor cell lines.

We have studied the pharmacological parameters of doxorubicin resistance in three lines of murine cells selected by long-term culture in the presence of this drug or vincristine. A line originating from rat hepatoma spontaneously presented an intrinsic doxorubicin resistance as compared to the other lines, originating from a rat glioblastoma and from simian-virus-40-transformed mouse hepatocytes. This intrinsic resistance, as well as the doxorubicin resistance exhibited by the vincristine-selected glioblastoma variant, could be entirely attribute to decreased drug accumulation due to drug efflux. In contrast, the doxorubicin-selected variants of the three lines exhibited an intracellular tolerance to this drug. Despite a reduction in drug accumulation when exposed to the same amount of doxorubicin, they accumulated 6-12 times more doxorubicin than wild lines when submitted to equitoxic exposures. Verapamil could restore in these lines the doxorubicin accumulation observed in sensitive lines but could not restore doxorubicin cytotoxicity. Quantitative evaluation of P-glycoprotein expression by Western blotting with the C219 antibody indicated that the wild hepatoma line overexpressed P-glycoprotein by a factor of 5 in comparison with the other wild lines, and that the vincristine-selected glioblastoma variant overexpressed this protein almost as much as the doxorubicin-selected variants. These observations favor the existence of P-glycoprotein-independent mechanisms of doxorubicin resistance, which are added to the classical multidrug-resistant phenotype in doxorubicin-selected highly resistant variant cell lines.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1993

Functional characterization of liver-associated lymphocytes in patients with liver metastasis.

BACKGROUND: The liver-associated lymphocytes (LAL) population is mainly composed of cells with natural killer (NK) activity expressing the CD3+/-CD56+ phenotype. No evident difference has been found in the phenotypic data between patients with benign or malignant liver disease. In this study, the cytotoxic pattern of this population has been characterized from patients who underwent an operation for benign or metastatic liver disease. METHODS: LAL were isolated by sinusoidal high-pressure lavage from partial hepatectomies. Phenotype was characterized by flow cytometry, and cytotoxicity was evaluated by standard 4-hour 51Cr release assays against NK and lymphokine-activated killer (LAK)-sensitive targets. RESULTS: In patients with benign liver disease, LAL showed spontaneous high levels of NK activity and LAK activity compared with peripheral blood lymphocytes. In patients with metastatic liver disease, no difference was observed in the levels of NK activity between LAL and peripheral blood, and the level of LAK activity was far lower than that expressed in patients with benign liver disease. CONCLUSIONS: These results show that the cytotoxic pattern of peripheral blood lymphocytes does not mirror that of LAL. In patients with benign liver disease, LAL are in a state of activation, whereas the decreased level of LAL cytotoxicity in patients with metastatic liver disease suggests that the cytotoxic activity of these cells could be inhibited by the presence of suppressive factors.

Adult↗
PubMed1993

Reversal of multidrug resistance by a new lipophilic cationic molecule, S9788. Comparison with 11 other MDR-modulating agents in a model of doxorubicin-resistant rat glioblastoma cells.

We have compared the properties of the novel multidrug resistance modulator, S9788, to a panel of 11 well-known modulators in a model of rat glioblastoma cells resistant to doxorubicin and displaying a P-glycoprotein-mediated multidrug-resistance phenotype complemented by a mechanism of intracellular drug tolerance not yet identified (Br J Cancer 1992, 65, 538-544). S9788, like most modulators, was able to completely restore drug accumulation in the resistant line to the level obtained in the sensitive cells. This was obtained with 10 mumol/l of modulator, which is slightly higher than required for cyclosporine A (3 mumol/l) verapamil and nicardipine (6 mumol/l), but lower than for amiodarone, trifluoperazine and dipyridamole (20 mumol/l), tamoxifen and diltiazem (40 mumol/l), quinine, quinidine and nifedipine (> 100 mumol/l). Complete restoration of drug cytotoxicity was, however, obtained only with amiodarone, and a residual resistance factor of 4 could not be overcome by cyclosporine A or S9788, while other modulators gave residual resistance factors of 5-20 (trifluoperazine, tamoxifen, verapamil, quinine, nicardipine, dipyridamole) or even higher (diltiazem, quinidine, nifedipine). When studying doxorubicin accumulation obtained for an exposure to the IC50 of this drug, it appeared that some modulators were able to decrease this "intracellular IC50" independently of their efficiency in resistance reversal (cyclosporine A, S9788, amiodarone, trifluoperazine, quinine, tamoxifen), thus reversing intracellular drug tolerance, whereas other modulators could not reduce this parameter (verapamil, nicardipine, dipyridamole, diltiazem, quinidine). It is suggested that drugs of the first group could be able to segregate doxorubicin in subcellular compartments from which it could not reach its nuclear targets.

Animals↗
PubMed1992

Genetic modulation of antigen presentation by HLA-B27 molecules.

In studies of antigenic peptide presentation, we have found a healthy volunteer whose lymphoblastoid cells were unable to present three different virus-derived epitopes to cytotoxic T lymphocytes (CTL) despite expressing the correct restricting HLA-B27 molecules on the cell surface. B cell lines were established from other members of the donor's family, including individuals suffering from ankylosing spondylitis and related diseases, and were tested for their ability to function as target cells in the same assay. None of the eight B cell lines that expressed HLA-B27 presented a known peptide epitope to CTL. However, cells from a family member that expressed HLA-B8 could present an epitope peptide restricted by that molecule. The B27 molecule in this family proved to be the B2702 subtype on isoelectric focusing gels, appearing in exactly the same position as B2702 from other cell lines that did present the peptide. To exclude mutations resulting in noncharged amino acid substitutions, cDNA coding for B2702 was cloned from the proband's cell line and sequenced. No coding changes were found. The cloned cDNA was transfected into HLA-A- and B-negative HMy/C1R cells, and the B2702 molecules generated in this environment rendered these cells, after incubation with peptide, susceptible to lysis by peptide-specific CTL. These data are compatible with the presence of a factor(s), possibly HLA linked, interfering with antigen presentation by otherwise normal B2702 molecules in this family.

Antigen-Presenting Cells↗
PubMed1992

P-glycoprotein overexpression cannot explain the complete doxorubicin-resistance phenotype in rat glioblastoma cell lines.

We have associated pharmacological studies to a semi-quantitative evaluation of P-glycoprotein(s) expression, to establish if classical multidrug resistance (MDR) could account for the complete resistance phenotype exhibited by progressively doxorubicin-resistant rat glioblastoma cells. Three resistant variants (C6 0.001, C6 0.1 and C6 0.5) of the C6 glioblastoma cell line (C6 S) were selected by long-term culture in the presence of three concentrations of doxorubicin (0.001, 0.1 and 0.5 microgram.ml-1 respectively). The degree of doxorubicin resistance was respectively 7, 33 and 400, and all the cell variants were cross-resistant to m-AMSA, etoposide and vincristine. Doxorubicin incorporation was reduced similarly in all resistant cells, irrespective of the level of resistance. When exposed to their respective doxorubicin IC50, the 7-fold resistant cells had the same intracellular drug incorporation as the sensitive cells, whereas the 33-fold and 400-fold resistant cells could incorporate respectively 3.7 and 17 times more drug. The ratio of doxorubicin exposures required for 50% DNA synthesis inhibition and 50% growth inhibition was dependent on the degree of resistance; this ratio was 12.8 in C6 S, 11.6 in C6 0.001, 6.3 in C6 0.1 and 1.8 in C6 0.5. P-glycoprotein(s) overexpression was of the same magnitude as the resistance factor in variants C6 0.001 and C6 0.1, but was lower than resistance factor in variant C6 0.5. Reversal of drug incorporation by verapamil was complete in all resistant cell lines; however, reversal of doxorubicin cytotoxicity was complete only in the 7-fold resistant line and was only partial in the most resistant lines, which remained 10-fold and 20-fold resistant to doxorubicin. These results suggest that classical MDR was the first phenotype selected by doxorubicin in C6 0.001, whereas mechanism(s) of doxorubicin resistance other than classical MDR are added in the most resistant lines.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1992

Pharmacokinetics and metabolism of 4'-iodo-4'-deoxy-doxorubicin in humans.

PURPOSE: 4'-iodo-4'-deoxydoxorubicin is a new anthracycline that currently is under clinical evaluation. To improve the management of future trials, we have determined its pharmacokinetics and metabolism during a phase I/II study and have tried to relate the parameters obtained to the hematologic toxicity of the drug in terms of the survival of blood cells. PATIENTS AND METHODS: The pharmacologic study included 19 patients who were entered at dose levels that ranged between 6 and 90 mg/m2; nine patients were treated at 80 mg/m2, which is close to the maximum recommended dose level. Blood sampling was performed from the end of the bolus infusion to 48 hours after treatment. Drug and metabolites were extracted and analyzed by high-performance liquid chromatography (HPLC), and the data were processed by nonlinear fitting to multicompartment models. RESULTS: Plasma concentrations were best fitted to a three-compartment model with half-lives of 5.2 minutes, 0.79 hours, and 10.3 hours. The total body clearance and volume of distribution at steady state were high (350 L/h/m2 and 2,065 L/m2). The drug was metabolized extensively to a 13-dihydroderivative, 4'-iodo-4'-deoxy-doxorubicinol; the mean area under the curve (AUC) ratio metabolite/parent drug was the highest observed ever for an anthracycline (12.1 +/- 7.4); the metabolite was cleared from the plasma with an elimination half-life of 15.3 hours. The AUCs of the parent compound and its metabolite were related linearly to the dose administered, and showed no saturation phenomenon. Urinary excretion was studied in nine patients and showed a cumulative elimination of less than 6% of the dose administered, two thirds of which were eliminated in the first 12 hours after injection. Ninety-three percent to 100% of the elimination of fluorescent compounds occurred in the form of the metabolite. Drug concentration in five tumor samples showed a rapid uptake of the drug from plasma and a preferential uptake of the parent drug compared with the metabolite. Blood cell counts after 4'-iodo-4'-deoxydoxorubicin treatment showed significant correlations among the surviving fractions of both granulocytes and platelets and the AUCs of the parent drug and its metabolite; the most significant correlations were obtained for the granulocytes and the metabolite. Significant correlations between AUCs and blood-cell survivals were maintained, even if only the nine patients treated at the dose of 80 mg/m2 were taken into account for the computation. CONCLUSIONS: Our results especially show that myelosuppression that is induced by 4'-iodo-4'-deoxydoxorubicin can be well predicted by the measure of the AUC of the drug and its metabolite. This could be used for the further development of the drug toward high-dosage schedules.

Blood Platelets↗
PubMed1991

Refractory period phenomenon in the induction of tissue factor expression on endothelial cells.

Tissue factor (TF) is the first factor of the extrinsic pathway of coagulation. Normally, TF is not expressed on the surface of endothelial cells. However, expression of TF can be induced in these cells in response to stimulation by diverse inflammatory mediators such as interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), lipopolysaccharide (LPS), and phorbol 12-myristate 13-acetate (PMA). We have studied the effect of these mediators on the kinetics of the induction of TF-related procoagulant activity (PCA) on human umbilical vein endothelial cells (HUVECs). PCA is transiently induced on HUVECs, attaining a peak some 4 to 8 hours after addition of inflammatory agents, with maximal accumulation of TF messenger RNA (mRNA) occurring 3 to 5 hours earlier. Because the expression of PCA by treated HUVECs returns to basal levels by 20 to 30 hours, we examined the response of these cells to a second inflammatory stimulus. Continuous incubation of cells with a single inflammatory agent for 24 to 48 hours induces a hyporesponsive state with respect to the reinduction of TF expression by the same agent (14% of the initial stimulation for IL-1 beta, 39% for TNF-alpha 30% for LPS, and 7% for PMA). Such a diminution in PCA was also observed in the levels of TF mRNA. By contrast, pretreatment of HUVECs with one agent did not dramatically affect the reinduction of TF by any of the three other factors. We subsequently focused our attention on the induction of the autologous refractory period by IL-1 beta. De novo protein synthesis was not required during the preincubation of ECs for hyporesponsiveness to be observed. The establishment of the refractory state did not depend on the downmodulation of IL-1 beta receptor affinity or expression. Moreover, pretreatment of HUVECs with IL-1 beta increased prostacyclin (PGI2) production in response to a second stimulation by IL-1 beta, although such cells were unable to reexpress TF under the same conditions. This result suggests that distinct secondary messenger pathways are involved in TF induction and PGI2 synthesis by IL-1 beta in HUVECs.

Endothelium, Vascular↗
PubMed1990

Structural homologies between two HLA B27-restricted peptides suggest residues important for interaction with HLA B27.

Recently we described an HLA B27-restricted peptide derived from HIV gag p24 protein. In this study we have isolated an HLA B27-restricted peptide from the nucleoprotein (NP) of influenza A virus. The shortest fragment recognized by cytotoxic T lymphocyte (CTL) is eight amino acids long, residues 384-391. Comparison of the sequence of these two HLA B27 restricted peptides reveals homologies which can be aligned from one peptide to the other. Of the eight residues, two are identical: tryptophan and isoleucine. Both peptides have a positively charged residue at the N terminus, lysine at position 265 of gag and arginine at position 384 of NP. Using modified peptides we have shown that lysine or arginine is crucial for the interaction with HLA B27. The wild-type gag peptide blocked CTL recognition of NP peptide by influenza-specific CTL, but removal of the lysine prevented inhibition of NP peptide recognition. The importance of these charged residues was confirmed by the observation that truncated NP and gag peptides where the lysine or arginine was removed were not recognized by specific CTL. Further studies showed that the tryptophan residue influenced the association of the gag peptide with HLA B27, because the affinity of the gag peptide for B27 was strongly increased after replacing this residue with a leucine or a tyrosine. However, these peptides were not recognized by gag-specific CTL, suggesting that the tryptophan may interact with both HLA B27 and T cell receptor. These observations should help in the identification of HLA B27-restricted peptides from other viruses or organisms.

Amino Acid Sequence↗
PubMed1990

An HIV-1 and HIV-2 cross-reactive cytotoxic T-cell epitope.

The HLA-B27-restricted HIV gag cytotoxic T-lymphocyte (CTL) epitope, 265-279, is highly conserved amongst HIV-1 isolates, only one, HIV-1ELI, having a single amino acid substitution. Over the same region HIV-2 differs by five amino acids. As a broadly cross-protective AIDS vaccine should protect against infection from all isolates of HIV-1 and HIV-2, we tested CTL specific for the HIV-1 265-279 epitope with peptide analogues from HIV-1ELI, HIV-2 and two simian immunodeficiency virus (SIV) isolates, and with recombinant vaccinia viruses expressing the respective gag genes, to determine whether there was any cross-reactivity for this CTL epitope. CTL from the HIV-1-infected donor could recognize the HIV-1ELI peptide, the HIV-2 peptide and recombinant vaccinia virus-infected target and one of the two SIV peptide-treated targets. Epitopes that exhibit such cross-reactivity may be valuable in vaccine design.

Amino Acid Sequence↗
PubMed1990

Pharmacokinetics of idarubicin after oral administration in elderly leukemic patients.

We have studied the plasma pharmacokinetics of idarubicin (4-demethoxy daunorubicin) in 11 elderly patients suffering from acute myeloblastic leukemia receiving orally 30 mg/m2 per day for 3 consecutive days. Idarubicin culminated in plasma 4 hr after administration and followed three similar time courses after the three administrations. Idarubicinol (13-dihydro-4-demethoxy daunorubicin) was the only fluorescent metabolite in plasma and no aglycone could be detected; idarubicinol concentration was always higher than that of unchanged idarubicin. Due to its protracted half-life (64 hr in this study), this metabolite progressively accumulated and the ratio of the areas under the curve (0-24) idarubicinol/idarubicin increased from day to day. By comparison to results obtained after i.v. administration of the drug in another study, the bioavailability of idarubicin alone can be estimated to about 21%, whereas the bioavailability of the sum idarubicin + idarubicinol is about 41%.

Administration, Oral↗
PubMed1989

CD44 contributes to T cell activation.

We demonstrate here that the CD44 molecule, which mediates lymphocyte adhesion to high endothelial venules (HEV), is also involved in the delivery of an activation signal to the T cell. We have produced a CD44 mAb (H90) which is able to block the binding of lymphocytes to high endothelial venules. H90 had no effect on [3H]TdR incorporation of whole PBL stimulated by lectins, allogeneic cells, or CD3 mAb in the soluble phase; in contrast, it strongly increased [3H]TdR incorporation of PBL stimulated by CD2 pairs of mAb or by CD3 mAb linked to the plastic culture plates, when purified T cells were used, H90 mAb could efficiently induce them to proliferate after a primary signal of activation delivered via cross-linked CD3 or via CD2, an effect mediated by Il-2 synthesis and Il-2R expression. Thus, the effect of H90 mAb resembles the mitogenic effect of CD28 "9.3" mAb. However, several results show that CD28 and CD44 mediate different signals to the T cells: i) in contrast to CD28 mAb, CD44 mAb cannot complement the signal delivered by a soluble CD3 mAb, lectins, or PMA; ii) CD44 mAb, at the difference of CD28 mAb, cannot induce CD3+ thymocytes to proliferate in conjunction with a first signal provided via cross-linked CD3 or via CD2; iii) F(ab) fragments of H90 were efficient, whereas divalent fragments of CD29 9.3 mAb are required to produce activation signals; and iv) CD44 and CD28 mAb produce a very strong synergistic effect on T cell proliferation. These results fit with previous ones showing that endothelial cells can play the role of accessory cell in T cell activation and that a hierarchy of signaling can be delivered to T cells via CD3 and CD2.

Adjuvants, Immunologic↗
PubMed1989

Suppressor effects and cyclic AMP accumulation by the CD29 molecule of CD4+ lymphocytes.

Integrins are a superfamily of related molecules whose function, where known, is to mediate adhesion. The so-called very-late-activation antigen (VLA) family includes at least five distinct heterodimers, each composed of a unique alpha-subunit non-covalently associated with a common beta-subunit. Several members of the family have been shown to bind extracellular matrix proteins, but the function of VLA-4 is so far unknown. VLA-4 is the only member of the family detected on thymocytes and resting T cells. We show here that an antibody which recognizes the beta-subunit of VLA-4 (CD29) on T cells can inhibit CD4+ cell proliferation triggered by CD2 or CD3, and that binding of this antibody to activated T cells leads to an increase in cyclic AMP levels which is comparable to that elicited by forskolin. These negative signalling effects are unique to this antibody: other CD29 antibodies do not affect the growth of activated CD4 cells but enhance the proliferation of whole T cell populations and abrogate the suppressive effects of mitomycin-treated CD8 cells on CD4-cell growth. Taken together, our results indicate that VLA-4 functions in cell-cell interactions and that it is the target for the suppressive effects of CD8 cells on CD4 cells.

Antigens, Differentiation↗
PubMed1989

A 19-kDa human erythrocyte molecule H19 is involved in rosettes, present on nucleated cells, and required for T cell activation. Comparison of the roles of H19 and LFA-3 molecules in T cell activation.

We have previously described a molecule on the SRBC surface which, in addition to the sheep equivalent of LFA-3, is involved in the process of rosette formation. It is made of a single, 14- to 19-kDa, polypeptide chain, and we termed this molecule S14. We have now identified, on the human E a molecule with a similar Mr albeit somewhat higher (19 kDa). The mAb against H19 efficiently block autologous or homologous rosettes by binding to human E. In addition, purified H19 molecules block rosettes made with human E and SRBC in a dose-dependent manner. The H19 molecule, like LFA-3, is not limited to the E surface, but is also present on many nucleated cells, including T cells and monocytes. Moreover H19, like LFA-3, is required for T cell activation: when we stimulated whole PBMC anti-H19 blocked [H3]TdR incorporation triggered via CD3, but not via CD2, in contrast to anti-LFA-3 that inhibited activation via both pathways. When a mixture of highly purified T-PBL and autologous paraformaldehyde fixed accessory cells (AC) was cultivated, anti-H19 or anti-LFA-3 mAb bound to AC blocked T cell proliferation. When high amounts of rIL-1 (100 U/ml) were added to purified T-PBL, no AC were required to sustain their proliferation upon stimulation via CD2, contrary to stimulation via CD3. When lower amounts of rIL-1 (10 U/ml) were used, fixed AC were still necessary to sustain proliferation via CD2. In this latter situation, anti-H19 mAb bound to AC could no longer inhibit T cell proliferation, whereas the anti-LFA-3 mAb was still inhibitory. When T-PBL were stimulated via CD2 in the presence of 100 U/ml of rIL-1, anti-LFA-3 did not induce any inhibition. Thus the inhibitory effect of anti-H19 and anti-LFA-3 mAb can both be accounted for by an effect on the AC molecules only, and not on the T cell molecules. F(ab')2 fragments of anti-H19 mAb produced the same pattern of inhibition as the whole Ig molecule, excluding an effect via the FcR. Moreover, purified preparations of the H19 molecules also produced inhibition.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗