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G Delespesse

Publications and source records attributed to G Delespesse.

At least 127 records · Page 7Linked to original sources
PubMed1985

Demonstration of intracytoplasmic IgE in circulating lymphocytes of allergic individuals.

Cells containing intracytoplasmic IgE (IC IgE) were demonstrated in the peripheral blood mononuclear cells of atopic individuals by means of indirect immunofluorescence, employing mouse monoclonal anti-human IgE antibody. IC IgE-positive cells are low-density B cells as shown by centrifugation on discontinuous bovine serum albumin density gradient and by their reactivity with B1 monoclonal antibody specific to B lymphocytes, respectively. Further characterization of these cells by means of a rosette assay employing anti-Ig-coupled bovine erythrocytes indicated that these cells were surface IgE (sIgE) positive and sIgM negative. The data strongly suggest that activated IgE B cells are circulating in the blood of allergic individuals.

B-Lymphocytes↗
PubMed1985

Induction of IgA-specific suppressor activity in human T-lymphocyte cultures.

Cell-free supernatants of human circulating T-lymphocyte cultures incubated with secretory IgA (S-IgA) specifically suppressed both spontaneous IgA synthesis by B lymphocytes isolated from allergic individuals and pokeweek mitogen-induced IgA secretion by peripheral blood mononuclear cells. Cell-free supernatants of T-cell cultures incubated with IgE had no effect on IgA, IgG, or IgM synthesis. Hence, it is concluded that upon incubation with S-IgA, but not with another Ig class, T lymphocytes release IgA-specific suppressor factors.

Antibody Specificity↗
PubMed1985

Human cord blood suppressor T lymphocytes: I. Phenotype and target of the inducer of suppressor cell factor.

The present study examines the characteristics of the cord suppressor T cells and their targets. When an inducer of suppressor T cell factor (TisF) from culture supernatant of alloantigen-activated cord lymphocytes was used as a source of suppression, adult lymphocyte response to soluble antigen candidin, alloantigens, and pokeweed mitogen were all suppressed. These results suggest that TisF acts primarily on T cells in an antigen-nonspecific fashion. Furthermore, preculture T cell irradiation, but not T8+ cell depletion, of adult lymphocytes abrogated the suppressive effect of TisF on the PWM-stimulated IgG production, suggesting that the target of TisF belongs to the radiosensitive T8-(T4+) T cell subset. When different cord T cell subsets were tested for suppressor activity, only radiosensitive T4+ cells were capable of suppressing IgG production by adult lymphocytes. Neither preculture T8+ cell depletion nor irradiation of adult T cells affected the suppression. Taken together, these results suggest that the suppressor activity of cord T cells originated from an inducer of suppressor cells that activates radiosensitive T4+ suppressor effector cells through TisF. In turn, these effector cells act on either radioresistant T4+ helper T cells or B cells or both.

Adult↗
PubMed1985

In utero immunization of the fetus to tetanus by maternal vaccination during pregnancy.

We tested 36 pairs of umbilical cord blood and maternal sera collected at the time of delivery by radioimmunoassay and by Western blot analysis for IgG or IgM antitetanus antibodies (anti-TT). Twenty-one participants had received a recall injection of tetanus toxoid at various periods during pregnancy. Maternal vaccination in the last trimester of pregnancy was associated with the presence of IgM anti-TT in the cord blood sera; these were not detected in neonatal sera from mothers who were not vaccinated during pregnancy or who received the booster injection during the first two trimesters of gestation. The results could not be ascribed to artifacts such as the contamination of neonatal sera by maternal blood, the contamination of the anti-IgM antisera by antiidiotypes, or by the presence of neonatal IgM rheumatoid factor binding to immune complexes made of maternal IgG anti-TT and radiolabelled TT. Hence, it is concluded that maternal vaccination during the last trimester of pregnancy may induce in utero active immunization of the fetus.

Female↗
PubMed1985

Detection and characterization of monoclonal antibodies specific to IgE receptors on human lymphocytes by flow cytometry.

BALB/c mice were immunized with human lymphoblastoid cells (RPMI 8866 cells) expressing surface receptors for IgE (Fc epsilon R). Spleen cells from animals displaying high titres of anti-Fc epsilon R antibodies were fused with HGPRT-deficient NSI myeloma cells. Anti-Fc epsilon R antibodies were identified by a flow cytometric assay based on their ability to block the binding of IgE-coated fluorescent latex particles to Fc epsilon R-positive cells. Fourteen monoclonal hybridoma cell lines secreting antibody of the required specificity were amplified in tissue culture and then grown in the peritoneal cavity of BALB/c mice in order to obtain ascitic fluids with high antibody titres. The specificity of each monoclonal antibody (Mab) to lymphocyte Fc epsilon R was shown by the following observations: (i) the intact monoclonal antibody molecule or, in some cases, its F(ab')2 fragments blocked the binding of IgE to several Fc epsilon R(+) cell lines different from that employed for the initial immunization; (ii) the Mab bound directly to all the Fc epsilon R(+) cell lines tested, but not to several Fc epsilon R(-) cells as determined by indirect immunofluorescence; (iii) the binding of Mab to Fc epsilon R(+) cells was selectively blocked by IgE, but not by the other classes of Ig; and (iv) Mab had no effect on the binding of IgG to Fc gamma R on normal human peripheral blood mononuclear cells (PBMC).

Animals↗
PubMed1985

Modulation of immune response in aged humans through different administration modes of thymopentin.

Thymopentin, a synthetic pentapeptide corresponding to the active site of thymopoietin, has been shown to restore antibody production in old mice. A decrease in immune response can also be observed in elderly humans, which is mainly caused by defective T cell function. The present study shows that the immunomodulating properties of thymopentin involve both specific and nonspecific responses in a population of elderly people vaccinated with keyhole limpet hemocyanin (KLH) antigen. Furthermore, it is demonstrated that these effects depend upon the mode of administration of thymopentin: The specific KLH antibodies (IgM and IgG), measured by solid-phase radioimmunoassay, reach the highest titers after subcutaneous injection. The lowest titers are produced after intravenous injections, whereas the responses to placebo are between these two ranges. The nonspecific immunoglobulin production, measured by nephelometry, does not follow the same pattern, suggesting that different regulatory mechanisms are involved. Future implications of these findings are discussed.

Adjuvants, Immunologic↗
PubMed1984

Immunoregulatory function of human cord blood lymphocytes on immunoglobulin production.

The functional maturity of human umbilical cord blood B lymphocytes and the immunoregulatory activity of cord T lymphocytes were assessed by measuring the in vitro immunoglobulin production by B cells from either cord or adult blood. Supernatants from 48-hr pokeweed-mitogen (PWM) stimulated cord or adult lymphocyte cultures were added to cord or adult B cell cultures in the presence of PWM; a significant amount of immunoglobulin was produced in adult B cell cultures only. Adult B or T cells were then cocultured with cord T or B cells; a significant amount of immunoglobulin was again found only in adult B cell cultures. These results indicated that cord B cells were functionally immature and that cord helper T cell function was adequate but masked by excessive suppressor activity. Indeed, addition of cord T cells but not of allogeneic adult T cells to PWM stimulated adult lymphocyte cultures inhibited their immunoglobulin production; this confirmed cord T cells' increased suppressor activity. Cord T cells were not intrinsically suppressive since they failed to suppress immunoglobulin production by Epstein-Barr Virus (EBV) transformed B cells. They could be activated, however, by PWM or allogeneic cells (in mixed lymphocyte cultures) and their effect was mediated via soluble factor(s) as demonstrated by the suppressor effect of these culture supernatants on immunoglobulin production by unfractionated adult lymphocytes. In contrast, when these supernatants were added to T cell-depleted adult lymphocyte cultures, enhancement rather than suppression was observed. These results indicated that the soluble factor(s) released by Cord T lymphocytes was not suppressing per se but induced suppression through activation of suppressor cells.

Adult↗
PubMed1984

Characterization of cellular infiltrates in skin lesions of atopic eczema by means of monoclonal antibodies.

Frozen skin biopsies from 3 acute and 3 chronic lesions of atopic dermatitis were examined by means of various ortho-monoclonal antibodies (OKT3, 4] not equal to----4, OKT6, OKT8; OKIa and OKM1) in an indirect immunofluorescence technique. The results show that both T helper (T4) and T suppressor cytotoxic (T8) lymphocytes are present in the inflammatory infiltration which predominantly contained Ia mononuclear cells. Despite the absence of double staining procedure, the observations suggest that T4 cells predominate over T8 cells in the acute lesions whereas the reverse tendency is noted in the chronic lesions. T8 cells are found mainly in the superficial dermis or even in the epidermis; by contrast, T4 cells tend to be more deeply located in the dermis. The lesions are characterized by a dramatic increase in the number of Langerhans cells (OKT6, OKIa+) that are found not only in the epidermis but also in the dermis.

Adolescent↗
PubMed1984

In vitro synthesis of IgE by human lymphocytes. III. IgE-potentiating activity of culture supernatants from Epstein-Barr virus (EBV) transformed B cells.

Seven Epstein--Barr virus (EBV)-transformed B cell lines were derived from circulating lymphocytes of two atopic and two non-atopic individuals, two preparations of cord blood lymphocytes and one tonsillar lymphocyte preparation. All the cell lines contained a significant proportion of cells expressing Fc epsilon R as detected by rosette formation with IgE-coated bovine erythrocytes (E-IgE) and by flow cytometry using IgE-linked to fluorescent microspheres. None of the cell lines displayed FcR for IgA, IgM or IgG. The cell-free supernatants (CFS) of EBV-transformed cells contained IgE-binding factors (IgE-BFs) detected by their ability to inhibit the binding to RPMI 8866 cells of either E-IgE or IgE-linked to microspheres. Whereas these CFS enhanced the synthesis of IgE and suppressed the synthesis of IgG by purified B lymphocytes isolated from the blood of allergic donors and cultured in the absence of stimulant, their effect on the synthesis of IgA or IgM was not predictable. CFS significantly enhanced the secretion of IgE by the U266 myeloma cell line without interfering with secretion of IgM, IgG or IgA by EBV-transformed cells. These data are in accord with similar properties of RPMI 8866 cells and suggest that B lymphocytes might play a regulating role in the IgE synthesis.

B-Lymphocytes↗
PubMed1984

Demonstration of auto-anti-idiotypic antibody cross-reacting with public idiotypic determinants in the serum of rye-sensitive allergic patients.

The present study documents the presence, in the serum of one allergic individual, of auto-anti-idiotypic antibodies cross-reacting with public idiotypic determinants expressed on human IgE and IgG anti-Rye I antibodies. Sera from rye-sensitive patients were tested for specific IgG and IgE antibodies to Rye I by double antibody. The IgG fraction, isolated from the serum of a patient with a history of previous hyposensitization therapy, was repeatedly absorbed on Rye-I-Sepharose as well as on IgM- and IgG-Sepharose to remove anti-Rye I antibodies as well as any possible anti-heavy or light chain activity. This IgG fraction, named anti-idiotypic fraction (a-IdF), blocked in a dose-dependent fashion the reaction of IgG and IgE anti-Rye I antibodies with Rye I antigen. The a-IdF also blocked the binding of anti-rye antibodies to Rye I antigen in the serum of 20 unrelated allergic patients, indicating that these anti-Rye I antibodies bore public idiotypic determinants.

Adolescent↗
PubMed1984

[Determination of circulating lymphocyte subpopulations in atopic dermatitis using monoclonal antibodies].

Monoclonal antibodies were used to determine the level of circulating helper and suppressor T cells in 34 infants and adults with severe atopic dermatitis and in normal controls. The percentage of OKT3 (total T lymphocytes) was reduced significantly in all the atopic infants. The percentage of OKT8 (suppressor-cytotoxic T lymphocytes) was reduced significantly in all patients with active lesions. The percentage of T gamma lymphocytes was reduced in all the atopic patients with or without active lesions.

Adolescent↗
PubMed1984

In vitro synthesis of IgE by human lymphocytes. II. Enhancement of the spontaneous IgE synthesis by IgE-binding factors secreted by RPMI 8866 lymphoblastoid B cells.

RPMI 8866 lymphoblastoid cells, known to express surface Fc epsilon R, were tested for their ability to regulate the in vitro synthesis of human IgE. Cell-free supernatants (CFS) of RPMI 8866 cells enhanced in a dose-dependent fashion the spontaneous IgE synthesis by B cells of allergic individuals. For maximum activity the CFS had to be added during the first 3 days of culture. CFS did not significantly alter the spontaneous synthesis of IgM or IgG, but they suppressed IgA synthesis both in B cell cultures and in pokeweed mitogen-stimulated peripheral blood mononuclear cells cultures. Cyclosporin A did not suppress either the spontaneous Ig production by B cells nor the IgE-potentiating activity of CFS. The enhancing activity of CFS was related to its content in IgE binding factors (IgE-BFs); these factors were detected by their ability to inhibit the rosetting of RPMI 8866 cells with IgE-coated erythrocytes (E-IgE). Both the IgE-BFs and the IgE-potentiating activity of the supernatants of RPMI 8866 cell cultures could be removed by absorption with IgE-Sepharose, from which they could subsequently be eluted with glycine-HCl buffer. IgE-BFs were identified as glycoproteins on the basis of their sensitivity to trypsin and to neuraminidase. By filtration of the RPMI 8866 cell supernatants through a Sephadex G75 column, IgE-binding activity was found to be associated with two fractions with molecular sizes in the range of 10,000-15,000 and 30,000-40,000. The IgA-suppressing activity of the RPMI 8866 culture filtrates could be absorbed with sIgA-Sepharose from which it was subsequently recovered by elution with glycine-HCl buffer. Most unexpectedly, sIgA-Sepharose also removed IgE-BFs and IgE-potentiating activity from the RPMI 8866 supernatants; both could be recovered by subsequent elution from sIgA-Sepharose with gycline-HCl buffer. These data are provisionally interpreted as indicating that the IgE-BFs secreted by RPMI 8866 cells had affinity for both IgE and sIgA and that they exerted a reciprocal effect on the in vitro synthesis of IgE and IgA.

B-Lymphocytes↗
PubMed1984

In vitro synthesis of IgE by human lymphocytes. IV. Suppression of the spontaneous IgE synthesis by IgE-binding factors secreted by tunicamycin-treated RPMI 8866 cells.

It was previously shown that RPMI 8866 cells released IgE-binding factors (IgE-BFs) capable of enhancing the spontaneous in vitro synthesis of IgE by purified B lymphocytes isolated from allergic individuals. In the present study, the influence of tunicamycin, an inhibitor of protein glycosylation, on RPMI 8866 cells was investigated with regard to: (i) the expression of surface receptors for IgE; (ii) the release of IgE-BFs into the culture supernatants, and (iii) the biological activity of IgE-BFs. After preincubation for 60 min with tunicamycin (1 microgram/ml), RPMI 8866 cells were cultured for 48 hr in HB 101 serum-free medium; the culture supernatant was then filtered, concentrated, and its biological activity was compared to that of a parallel culture supernatant from untreated RPMI 8866 cells. The results of these experiments indicate that exposure of RPMI 8866 cells to tunicamycin resulted in: (i) a reduction of surface Fc epsilon R; (ii) no effect on the release of IgE-BFs into the culture supernatant, and (iii) the conversion of IgE-potentiating factors into IgE-suppressing factors. The latter factors suppressed the IgE secretion by U266 myeloma cells and completely inhibited the activity of IgE-potentiating factors on B lymphocytes from allergic individuals. IgE-BFs secreted by tunicamycin-treated cells had no effect on the production of IgG, IgA or IgM by normal or EBV-transformed B cells.

Antibodies, Neoplasm↗
PubMed1984

In vitro synthesis of IgE by human lymphocytes. I. The spontaneous secretion of IgE by B lymphocytes from allergic individuals: a model to investigate the regulation of human IgE synthesis.

In view of the controversial data in the literature regarding the in vitro IgE synthesis by human lymphocytes, the conditions for culture of lymphocytes and the methodology for measurement of the IgE produced are described in detail. In the absence of any added mitogen, enriched B cell preparations derived from 70% of allergic donors actively secreted 100 to 3200 pg/ml of IgE after culture for 7 days, at which time the cell viability was higher than 85%. In comparable B cell cultures derived from non-allergic donors, only trace amounts of de novo synthesized IgE were detected in 20% of the cases. All B cell cultures actively secreted IgG, IgA, IgM and there was no apparent relationship between the secretion of IgE and that of the other classes of Ig. By contrast, the synthesis of IgE by unfractionated peripheral blood mononuclear cells of allergic individuals, which were stimulated with pokeweed mitogen (PWM) under several experimental conditions, was not consistently reproducible, i.e. the spontaneous synthesis of IgE in such cultures was either suppressed or enhanced by PWM. The most important finding was that the secretion of IgE was selectively enhanced by supplementing the B cell cultures with cell-free supernatants (CFS) of cultures of neonatal lymphocytes which had been preincubated with 10 micrograms/ml IgE. It is, therefore, concluded that B cell cultures from allergic individuals constitute an appropriate model for investigations of the mechanisms underlying the regulation of human IgE synthesis.

Adult↗
PubMed1984

Immunomodulation with thymopentin in humans.

The effect of thymopentin administered i.v. or s.c. on the levels of circulating specific IgM and IgG KLH (key-hole limpet haemocyanine) antibodies and non-specific immunoglobulins were measured at weekly intervals in elderly volunteers for three subsequent weeks after vaccination with 500 micrograms KLH. As compared with the placebo group, specific IgM and IgG antibody responses significantly increased in the s.c. treated group, but remained at significantly lower levels in the i.v. treated groups. Increases in non-specific immunoglobulin levels were observed after vaccination in the placebo group; no such increases appeared in the groups treated with thymopentin. The results demonstrate the immunomodulatory effect of thymopentin in humans. It is assumed that, depending on the route of application (which indirectly represents different doses), thymopentin can either stimulate or inhibit immune processes. As an immunomodulator it may represent a new therapeutic tool for immunostimulation as well as for specific immunosuppression.

Adjuvants, Immunologic↗