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G Delespesse

Publications and source records attributed to G Delespesse.

198 records · Page 11Linked to original sources
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IgE-binding factors: their possible role in the regulation of IgE synthesis.

B cell-derived IgE-BFs (sCD23) are cleavage fragments of surface Fc epsilon R II. Their production is increased by IL4 and suppressed by IFN-gamma and IFN-alpha. IgE-BFs are likely to play a role in the regulation of human IgE synthesis as shown by the following two observations: i. MabER specifically blocks both the spontaneous IgE by synthesis by atopic B cells and the IL4-induced IgE synthesis by normal lymphocytes, ii. purified IgE-BFs enhance the IL4-induced and the spontaneous IgE synthesis. Soluble fragments of Fc epsilon R II also display BCGF-like activity although the exact structure of these fragments is not yet identified. The cDNA coding for Fc epsilon R II has been cloned and functionally expressed. The predicted amino acid sequence reveals no homology between human and rodent IgE-BFs indicating that they are unrelated molecules.

Animals↗
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IgE synthesis.

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Animals↗
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Maturation of human neonatal CD4+ and CD8+ T lymphocytes into Th1/Th2 effectors.

The increased susceptibility of neonates to infections has been ascribed to the immaturity of their immune system. More particularly, T cell-dependent responses were shown to be biased towards a Th2 phenotype. Our studies on the in vitro maturation of umbilical cord blood T cells suggest that the Th2 bias of neonatal response cannot be simply ascribed to intrinsic properties of neonatal T cells. Phenotypically, neonatal CD4+ T cells are more immature than their adult CD45RO-/RA+ naive counterparts and they contain a subset (10-20%) of CD45RO-/RA+ CD31- cells which is very low in adults and displays some unique functional features. The activation and maturation of neonatal CD4+ T cells is particularly dependent upon the strength of CD28-mediated cosignal which dictates not only the cytokine profile released upon primary activation but also the response to IL-12. Activation of adult as well as neonatal CD4+ T cells in the context of low CD28 costimulation yields to the production of low levels of only one cytokine, i.e. IL-2. In contrast, strong CD28 costimulation supports the production of high levels of type 1 (IL-2, IFN gamma and TNF beta) and low levels of type 2 (IL-4 and IL-13) cytokines by neonatal T cells. The low levels of naive T cell-derived IL-4 are sufficient to support their development into high IL-4/IL-5 producers by an autocrine pathway. The ability of IL-12 to prime neonatal CD4+ T cells for increased production of IL-4 (in addition to IFN gamma) is observed only when CD28 cosignal is minimal. Under optimal activation conditions (i.e. with anti-CD3/B7.1 or allogenic dendritic cells) the response and the maturation of neonatal and adult naive T cells are similar. Thus the Th2 bias of neonatal immune response cannot be simply ascribed to obvious intrinsic T cell defect but rather to particular conditions of Ag presentation at priming. Unlike CD4+ T cells, neonatal CD8+ T cells strictly require exogenous IL-4 to develop into IL-4/IL-5 producers. Most importantly, anti-CD3/B7-activated neonatal CD8 T cells coexpress CD4 as well as CCR5 and CXCR4 and are susceptible to HIV-1 infection in vitro.

Adult↗
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Suppressor T-lymphocytes in pregnancy.

Primiparous and multiparous healthy pregnant women were tested at the end of the gestation period, or immediately after delivery, for their lymphocyte reactivity to paternal or neonatal cells in mixed lymphocyte culture and in cell-mediate cytotoxicity assays. Freshly isolated maternal lymphocytes had no spontaneous cytotoxic activity against PHA-activated neonatal or paternal lymphocytes. In conventional 6-day mixed lymphocyte cultures and in cytotoxicity assays, maternal lymphocytes displayed a response similar to that of paternal or third party lymphocytes when stimulated with neonatal, paternal, or third party lymphocytes. By contrast, in 3-day mixed lymphocyte cultures maternal cells had a selectively lower response to paternal antigens (expressed either on cord blood cells or on paternal lymphocytes), than to unrelated alloantigens. Removal of T-lymphocytes with IgG receptors (T gamma), or of T-lymphocytes reacting with OKT8 monoclonal antibody, corrected the depressed response of maternal cells in these 3-day cultures. It is suggested that circulating maternal lymphocytes contain antigen-specific suppressor cells characterized by their membrane receptors for IgG and the T8 antigen.

Adolescent↗
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OX40-Mediated cosignal enhances the maturation of naive human CD4+ T cells into high IL-4-producing effectors.

Our previous studies have indicated that naive human CD4+ T cells of neonatal or adult origin may be the initial source of IL-4 which is required for their development into Th2 effectors. In addition to minute amounts of IL-4, anti-CD3/B7.1-activated naive cells also release readily detectable levels of IL-13 and IFN-gamma. The production of IL-4 and IL-13 by naive T cells is differentially regulated by TGF-beta and IL-12. Shortly after activation, naive T cells express surface OX40, a TNF-R family member whose ligand (OX40L) is constitutively expressed on a subset of dendritic cells. Engagement of OX40 on activated naive T cells increases their expression of IL-4 and IL-13, suppresses that of IFN-gamma and promotes their development into Th2-like effectors.

Adult↗
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[Lymphocyte impairment in aging].

In vitro stimulation of peripheral blood lymphocytes by T mitogens and in MLC is reduced in aging. As the number of T lymphocytes and their antigenic power are in the normal range, a functional T-cell defect is anticipated in high age.

Adult↗
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[Cellular interactions in the lymphocyte response to PHA in old people].

Peripheral blood lymphocytes (PBL) from the same number of old subjects (OS) and young subjects (YS) have been separated into subpopulations of T cells (T1 and T2 fractions) and B cells. Phagocytes were removed by carbonyl iron. The recovery in T1 is reduced in the OS. Their PHA response is inhibited by monocytes but not by polynuclears (PN). The response of their peripheral T cells is not reduced but it is not enhanced by adding PN. There is a normal T-B cell interaction in the response to PHA. It is suggested that the impaired PBL response to mitogens is secondary to the reduction of their content in T1 lymphocytes.

Aged↗
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[Very extensive ulcers in a case of mixed cryoglobulinemia].

A young girl suffering from mixed cryoglobulinemia had shown since puberty ulcers of the lower limbs. A first very serious occurrence of necrotic lesions of the feet was stopped through the use of bilateral lumbar sympathectomy and grafts. A second extremely serious onset was cured using peridural lumbar anesthesia maintained for six weeks. D-penicillamine proved inefficient.

Adolescent↗
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Influence of total parenteral nutrition (TPN) on some immune parameters in malnourished surgical patients.

Twenty-one protein-calorie depleted patients were given for one week total parenteral nutrition (TPN) including Intralipid during a sixteen months' period (September 1975 - December 1976). Before TPN, lymphocyte proliferation response to 1 microgram/ml of phytohemagglutinin (PHA) was abnormally low, while immunoglobulin levels were in the normal range. After one week of TPN, lymphocyte response to PHA was significantly improved in patients exhibiting positive nitrogen balance but remained unchanged in the others. Immunoglobulin IgA, IGG, IgM levels tended to rise in most of the patients, while IgE concentrations remained unchanged. Addition of Intralipid at various concentrations to lymphocyte cultures of both patients and normal volunteers did not effect 3H-thymidine incorporation in the lymphocytes. Similarly, in vivo infusion of Intralipid in normal subjects did not have any effect on lymphocyte performance. This study shows that: 1. effective TPN can correct some alterations in immune parameters; 2. Intralipid does not seem to have any effect on the parameters measured in the present work.

Adult↗
PubMedDate not supplied

Cellular and humoral responses following one year of hyposensitization with aqueous and tyrosine adsorbed Dermatophagoides pteronyssinus extracts.

The present study compared the influence of hyposensitization treatment with a tyrosine adsorbed house dust mite solution (Migen) and an aqueous house dust mite (HDM) solution on the immunological parameters in 41 adult asthma and rhinitis patients. The immunological parameters included total IgE, spec. IgE and spec. IgG antibody determination, circulating immune complexes (CIC), lymphocyte response to Dermatophagoides pteronyssinus and to candidin and streptokinase-streptodornase (SKD). The two groups were compared to a control group of 123 non-allergic subjects. An increase in spec. IgG antibodies was found, with no change in the total and spec. IgE antibodies. The one year hyposensitization treatments had no influence on the appearance and level of CIC. A positive lymphocyte test to HDM antigen was found in 62% of the controls and in 70% of the treated patients. The response was significantly greater in the allergic patients than in the controls. Under the influence of hyposensitization, an early increase of the lymphocyte response to HDM, followed by a decrease, was noticed, whereas the response to candidin and to SKD remained unchanged. The present study demonstrated that the tyrosine adsorbed HDM extract had the same immunological consequences as the aqueous solution.

Adolescent↗
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[Impairment of humoral immunity in aging].

1) Aging is associated with a hypergammaglobulinemia consistng of an increase in the serum IgG and IgA, plus a reduction in the IgM. This is associated with an increase of the B lymphocyte circulating pool, and an increase of the ratio IgG-B cells; 2) There is a reduction of the serum concentration of natural isoagglutinins. 3) The secondary IgG response against diphteria toxin (DT) is similar in 15 young and 15 old subjects. 4) There is a reduction of the IgE response against DT in old subjects.

Aged↗