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M Larché

Publications and source records attributed to M Larché.

At least 37 records · Page 2Linked to original sources
PubMed1999

Immunoglobulin E-independent major histocompatibility complex-restricted T cell peptide epitope-induced late asthmatic reactions.

Intradermal administration of short overlapping peptides derived from chain 1 of the cat allergen Fel d 1 (FC1P) that did not cross-link IgE, elicited isolated late asthmatic reactions with no visible early or late cutaneous response in 9/40 cat-allergic asthmatics. Four of the nine were human histocompatibility leukocyte antigen DR13-positive, as compared with only 1/31 nonreactors. The other five reactors expressed either DR1 or DR4. To confirm major histocompatibility complex restriction, fibroblast cell lines transfected with HLA-DR molecules were used to present FC1Ps to cat allergen-specific T cell lines derived from subjects before peptide injection. FC1P3 (peptide 28-44 of Fel d 1 chain 1) was recognized in the context of DR13 alleles (DRB1*1301, 1302) and induced specific T cell proliferation and IL-5 production. T cells from a DR1(+) responder proliferated and produced IL-5 in the presence of FC1P3 and DR1 (DRB1*0101) fibroblast cell lines, whereas T cells from a DR4(+) subject recognized FC1P2 (peptide 22-37) when presented by DRB1*0405. We conclude that short, allergen-derived peptides can directly initiate a major histocompatibility complex-restricted, T cell-dependent late asthmatic reaction, without the requirement for an early IgE/mast cell-dependent response, in sensitized asthmatic subjects.

Adult↗
PubMed1998

Costimulation through CD86 is involved in airway antigen-presenting cell and T cell responses to allergen in atopic asthmatics.

Atopic allergic asthma is characterized by activation of Th2-type T cells in the bronchial mucosa. Previous reports have suggested an important role for costimulation through the CD28/CTLA4-CD80/CD86 pathway in allergen activation of T cells in animal models of inhaled allergen challenge. However, human allergen-specific lines and clones were reported to be costimulation independent. We therefore examined CD80 and CD86 dependence of allergen-induced T cell proliferation and cytokine production in peripheral blood and bronchoalveolar lavage from atopic asthmatic subjects and controls. Both allergen-induced proliferation and IL-5 production from PBMC were inhibited by CTLA4-Ig fusion protein and anti-CD86, but not anti-CD80 mAbs. When allergen-specific CD4+ T cell lines from peripheral blood were examined, proliferation and cytokine production were found to be independent of CD80 or CD86 costimulation. However, when cells obtained directly from the airways were examined, allergen-induced proliferation of bronchoalveolar lavage T cells from atopic asthmatic subjects was inhibited by anti-CD86 but not anti-CD80. In addition, bronchoalveolar lavage-adherent cells from asthmatic, but not control subjects showed APC activity to autologous T cells. This was also inhibited by anti-CD86 but not anti-CD80. Thus allergen-induced T cell activation and IL-5 production in the airway in asthmatic subjects is susceptible to blockade by agents interfering with costimulation via CD86, and this may hold therapeutic potential in asthma.

Abatacept↗
PubMed1997

Expression of IL-4 and IL-5 mRNA and protein product by CD4+ and CD8+ T cells, eosinophils, and mast cells in bronchial biopsies obtained from atopic and nonatopic (intrinsic) asthmatics.

We recently demonstrated bronchial mucosal expression of IL-4 and IL-5 at the mRNA and protein level in both atopic and nonatopic (intrinsic) asthma. In this report, using double immunohistochemistry (IHC) and in situ hybridization (ISH), we show that 70% of IL-4 and IL-5 mRNA+ signals co-localized to CD3+ T cells, the majority (>70%) of which were CD4+, although CD8+ cells also expressed IL-4 and IL-5 mRNA. The remaining IL-4 and IL-5 mRNA signals co-localized to mast cells and eosinophils. The cellular distribution of these mRNA species did not differ between atopic and nonatopic asthmatics. In contrast, double IHC showed that IL-4 and IL-5 immunoreactivity was predominantly associated with eosinophils and mast cells, with few IL-5 or IL-4 immunoreactive CD3+ T cells detectable. However, total IL-4- or IL-5-positive cells detected by IHC were <40% of the total mRNA+ cells, raising the possibility that insufficient cytokine protein accumulated within T cells to enable detection by IHC. We conclude that: 1) in atopic and nonatopic asthma CD8+ T cells, in addition to CD4+ T cells, mast cells and eosinophils express mRNA for IL-4 and IL-5; 2) whereas IL-4 and IL-5 mRNA expression was associated mainly with T cells, immunoreactivity for the corresponding protein products was detectable predominantly in eosinophils and mast cells; and 3) this discrepancy may be partly attributable to the relative insensitivity of double IHC technique that does not allow detection of cytokine protein in T cells where, unlike eosinophils and mast cells, there is no facility for storage and concentration in granules.

Adult↗
PubMed1997

IL-5 secretion by allergen-stimulated CD4+ T cells in primary culture: relationship to expression of allergic disease.

BACKGROUND: IL-5-producing allergen-specific T cells are thought to play a prominent role in the pathogenesis of allergic inflammation. We hypothesized that T cell allergen-driven IL-5 synthesis is elevated in patients with atopic disease as compared with that in atopic patients free of disease and nonatopic control subjects. OBJECTIVES: The purpose of this study was to compare IL-5 and interferon-gamma (IFN-gamma) secretion and proliferation by peripheral blood T cells from sensitized atopic patients with asthma, rhinitis, and no symptoms and from nonatopic control subjects in response to the allergen Dermatophagoides pteronyssinus (Der p) and the control recall antigen Mycobacterium tuberculosis purified protein derivative (PPD). METHODS: To measure allergen-induced IL-5 production and proliferation, we developed a short-term culture technique that required a single antigenic stimulation of freshly isolated peripheral blood mononuclear cells (PBMC). With this technique, we measured Der p- and PPD-induced IL-5 production and proliferation in PBMC from atopic patients with asthma who were allergic to Der p, atopic patients with rhinitis, atopic patients with no symptoms, and a group of nonatopic normal control subjects. In four experiments, CD4+ or CD8+ T cells were depleted from PBMC to confirm that IL-5 synthesis was T cell dependent. RESULTS: T cell IL-5 production, but not IFN-gamma production, in response to Der p was elevated in atopic patients with asthma and atopic patients with rhinitis compared with findings in atopic patients with no symptoms or nonatopic control subjects. IL-5 production was abrogated by depletion of CD4+, but not CD8+, T cells. In subjects with asthma, allergen-driven IL-5 production correlated with bronchial hyperreactivity. Allergen-induced proliferation was also higher in patients with asthma than in atopic subjects with no symptoms or nonatopic controls. T cell IL-5 and IFN-gamma production and proliferation in response to PPD were similar regardless of atopic status or disease. CONCLUSIONS: Elevated IL-5 production is a characteristic of allergen-specific peripheral blood CD4+ T cells from sensitized patients with atopic disease but not atopy per se.

Allergens↗
PubMed1996

A single strand conformation polymorphism study of CD40 ligand. Efficient mutation analysis and carrier detection for X-linked hyper IgM syndrome.

Mutations in the gene for CD40 ligand are responsible for the X-linked form of hyper IgM syndrome. However, no clinical or laboratory findings that reliably distinguish X-linked disease from other forms of hyper IgM syndrome have been reported, nor are there tests available that can be used to confidently provide carrier detection. To identify efficiently mutations in the gene for CD40 ligand, eight pairs of PCR primers that could be used to screen genomic DNA by single strand conformation polymorphism (SSCP) were designed. 11 different mutations were found in DNA from all 13 patients whose activated T cells failed to bind a recombinant CD40 construct. The exact nature of four of these mutations, a deletion and three splice defects, could not be determined by cDNA sequencing. In addition, SSCP analysis permitted rapid carrier detection in two families in whom the source of the mutation was most likely a male with gonadal chimerism who passed the disorder on to some but not all of his daughters. These studies document the utility of SSCP analysis for both mutation detection and carrier detection in X-linked hyper IgM syndrome.

Base Sequence↗
PubMed1996

Enhanced in vivo immunogenicity induced by an antibody to the IL-4 receptor-associated gp200-MR6 molecule.

Four murine IgG1 monoclonal antibodies, each with specificity for a human tumour-associated antigen, have been tested for their in vivo immunogenicity using a rabbit model. Surprisingly, one of these antibodies, MR6, was significantly more immunogenic than the remaining three reagents. This enhanced MR6 immunogenicity was not restricted to the immunoglobulin molecule itself, but also applied to a hapten (fluorescein isothiocyanate, FITC) when conjugated to the monoclonal antibody. In addition, the secondary immune response to an independent antigen, human haemoglobin, was higher when the antigen was administered simultaneously with MR6 than when co-injected with an isotype-matched control monoclonal antibody. The presence of the target antigen, gp200-MR6, on both rabbit and human leucocytes and epithelium, and its known association with human IL-4 function, raises the possibility that antibody MR6 may not only target immunogens to antigen-presenting cells, but may also enhance the ability of these cells to present antigen to the immune system. Antibodies to the gp200-MR6 may therefore find important clinical application as in vivo adjuvants.

Animals↗
PubMed1994

Inhibition of alloreactivity by mAb MR6: differential effects on IL-2- and IL-4- producing human T cells.

mAb MR6 has previously been shown to block both IL-4-induced T cell proliferation and IL-4-dependent IgE production, suggesting a functional association between the antigen detected by MR6 (gp200-MR6) and the human IL-4 receptor. In this study the potential modulatory effects of mAb MR6 on IL-4 function have been further analysed in alloantigen-specific assays for cytotoxic and Th cell maturation, mature cytotoxic T cell killing, helper cell proliferation, and generation of IL-2- and IL-4-producing Th cells in a mixed lymphocyte reaction (MLR). Our data show that mAb MR6 has an inhibitory effect on both clonal expansion and maturation of cytotoxic T lymphocyte precursors within the alloreactive T cell population. mAb MR6 had no effect on the maturation of Th lymphocyte precursors (assayed by IL-2 production). However, this mAb had striking differential effects on cytokine production in MLR cultures, showing total ablation of IL-4 but no alteration of IL-2 levels in the supernatant medium. The absence of IL-4 from culture supernatants could be due to the fact that mAb MR6 is blocking cytokine production, that it is speeding up IL-4 internalization and utilization or that it inhibits the expansion of the T cell subset(s) that secretes IL-4. The data demonstrate that the action of mAb MR6 is focused on the IL-4-producing population and raise the possibility that gp200-MR6 may play an important role in this aspect of IL-4 function.

Antibodies, Monoclonal↗
PubMed1994

Immunological events underlying the induction of T cell non-responsiveness.

T lymphocytes recognise antigen in the form of short peptides complexed with the class I and II products of the Major Histocompatibility Complex (MHC). Cellular activation follows T cell recognition of peptide-MHC complexes at immunogenic cell surface concentrations together with the participation of the appropriate costimulatory signals. Interaction of TCRs and peptide-MHC complexes under inappropriate conditions may result in antigen-specific non-responsiveness, commonly referred to as anergy. Here we review some recent model systems which have been employed to study the phenomenon of anergy and the use of peptides to induce antigen-specific non-responsiveness both in vitro and in vivo.

Allergens↗
PubMed1994

Hyper IgM syndrome associated with defective CD40-mediated B cell activation.

Recent studies show that most patients with X-linked hyper IgM syndrome have defects in the gene for CD40 ligand. We evaluated 17 unrelated males suspected of having X-linked hyper IgM syndrome. Activated T cells from 13 of the 17 patients failed to bind a soluble CD40 construct. In these patients, the sequence of CD40 ligand demonstrated mutations. By contrast, T cells from the remaining four patients exhibited normal binding to the CD40 construct. Sequencing of the cDNA for CD40 ligand from these patients did not show mutations. The possibility that hyper IgM syndrome in these four patients was due to abnormalities in the B cell response to CD40-mediated signals was examined. Peripheral blood lymphocytes were stimulated with anti-CD40 alone, IL4 alone or anti-CD40 plus IL4. In comparison with B cells from controls or patients with hyper IgM syndrome and mutant CD40 ligand, B cells from the patients with hyper IgM syndrome and normal CD40 ligand were defective in their ability to secrete IgE (P < 0.02) or express activation markers, CD25 and CD23 (P < 0.02) in response to stimulation with anti-CD40. The failure of these B cells to respond to CD40-mediated activation could not be attributed to a generalized deficiency in B cell activation because IL4 induced normal up-regulation of CD23 and CD25 expression. These findings indicate that hyper IgM syndrome may result from defects in expression of CD40 ligand by activated T cells or defects in CD40-mediated signal transduction in B cells.

Antigens, CD↗
PubMed1993

Fetal thymocyte potential for T cell receptor V gamma 3-J gamma 1 junctional modification.

Junctional modifications of T cell receptor (TcR) and immunoglobulin (Ig) gene joining regions provide great diversity to respective protein repertoires. The addition of non-germ-line-encoded nucleotides (N-regions) in the V-J gamma junction is one such modification which is developmentally regulated, rarely evident in the fetal animal, but common in the adult. A question has recently arisen as to whether developmentally patterned N-region additions in V-J gamma joins are a reflection of T cell progenitors which are committed to particular types of rearrangement prior to the event, or of changing environmental influences on uncommitted cell populations. To address this question with regard to the V gamma 3-J gamma 1 join, T cells were examined in the fetal thymic organ culture (FTOC), a system with which the environment of early progenitor cells could be deliberately altered. At various times following FTOC initiation, cells were isolated for examination by the polymerase chain reaction, cloning and sequencing. V gamma 3-J gamma 1 sequences within genomic DNA as well as cDNA were evaluated. Data from these studies revealed frequent N-region additions within V-J gamma joins among day 14 fetal thymocyte populations, a situation dissimilar from that in vivo. Also dissimilar from the in vivo situation was the degree of exonuclease activity evident in FTOC. The canonical V gamma 3-J gamma 1 join (a frequent junction lacking N-region addition) was recognized in all experiments, but was least common among DNA versus cDNA sequences. Results illustrate that early progenitor cell populations are not programmed to exclude junctional modifications from V gamma 3-J gamma 1 joins.

Animals↗
PubMed1993

Restricted usage of T-cell receptor V alpha sequence and variable-joining pairs after normal T-cell development and bone marrow transplantation.

TCR V alpha 3 and V alpha 5 transcripts in PBLs from healthy individuals of multiple age groups and from BMT recipients were analyzed. PCR, cloning, and sequencing studies revealed significant V-J junctional diversity among TCR transcripts from all tested blood samples, as provided both by N/P-region addition and exonuclease activity. However, results illustrated restrictions in TCR alpha diversity at several additional levels. First, V alpha 5 and V alpha 3 gene families, which were expected to be composed of multiple members, were dominated in each case by a single sequence at the transcript level. Second, restrictions existed in V-J pairing in that J alpha genes, which were encoded toward the 5' region of the locus, were rearranged frequently with V alpha 3 and rarely with V alpha 5. Conversely, J alpha genes encoded toward the 3' region of the locus preferentially rearranged with V alpha 5. Healthy individuals showed few differences with regard to V-J pairing patterns, while one of three BMT recipients demonstrated a skewed usage of 3' J alpha genes. In total, results demonstrated qualitative restrictions that may limit the working TCR repertoire in human peripheral tissues, both among BMT recipients and their healthy donors.

Adolescent↗
PubMed1992

Environmental influence on T cell receptor alpha gene rearrangement and expression in vitro.

Experiments were designed to test whether T cell progenitors are committed to particular T cell receptor (TcR) gene rearrangement and expression patterns (prior to rearrangement) or whether such patients are molded by the thymic microenvironment in which T cells develop. To this end, day 14 fetal thymocytes were removed from their normal environment and grown in organ culture (FTOC) for 5 to 12 days. RNA was extracted from organ-cultured cells, processed to cDNA, and TcR alpha sequences were amplified by the polymerase chain reaction for cloning and sequencing. By the examination of N-region additions and V-gene usage, and by the comparison of resultant patterns with those of early vs. adult stages of T cell differentiation in vivo, it was demonstrated that thymocytes in FTOC did not maintain early patterns of gene rearrangement. The thymocyte patterns were most dissimilar from those of normal, early ontogeny when interleukin-4 was added to FTOC. Taken together, results demonstrated the flexibility of T cell progenitors and that environment plays a critical role in the molding of TcR alpha rearrangement and expression patterns.

Animals↗
PubMed1992

Diversity of T-cell receptor alpha gene transcripts in the newborn and adult periphery.

Recent studies have demonstrated that the diversity of T-cell receptor alpha (Tcra) gene expression may be confined by a developmental program for gene rearrangement. To examine the effect of age on Tcra gene usage in peripheral tissues, a comparison of Tcr transcripts from newborn and adult mouse splenocytes was made. RNA was first isolated from the spleens of newborn (within five days from birth) and adult B10.BR mice. The polymerase chain reaction was then used to assess the presence of Tcra-V1, Tcra-V2, and Tcra-V3 gene sequences within the two RNA pools. The Tcra-V2 transcript was frequent in both newborn and adult populations and was therefore selected for sequencing analyses, by which V-gene family member and J gene usage could be delineated. Forty-one sequences were obtained, demonstrating Tcra-V2 gene family structure in the B10.BR mouse. Six family members were identified, of which four were new. Although there were differences in gene usage between newborn and adult animals, some junctional diversity added to the repertoire of both populations. A striking feature of V-J joining, as illustrated by this study, was the restriction of combinations based on the J gene location within the Tcra locus. The Tcra-V2 gene of dominant expression in the newborn (B10.BR.6) rearranged exclusively with the 30 most 5' Tcra-J genes. The Tcra-V2 gene of dominant expression at the adult stage (B10.BR.1) rearranged exclusively with the 21 most 3' Tcra-J genes in the locus. Thus, V-J combinatorial diversity was restricted in both newborn and adult mice, yielding a trend from 5'-3' Tcra-J gene usage with age. Inherent restrictions in V-J combinations should now be considered with regard to antigen responsiveness, particularly in the young animal. Qualitative restrictions in Tcr repertoire, compounding low T-cell numbers in peripheral tissues, may well contribute to functional voids and immunodeficiencies in early life.

Age Factors↗
PubMed1991

Environmental and allele-specific influences on T cell receptor gene rearrangement: skewed alpha, delta, and gamma gene rearrangement patterns in chimeric mice.

This study was performed as a means to examine the effects of environment and stem cell origin on the molding of T cell receptor gene rearrangements during T cell development. Lethally irradiated adult mice were first reconstituted with (C57BL/6 x DBA/2)F1 stem cells, which derived either from a fetal liver or adult bone marrow source. The gene rearrangements in the irradiated thymi were then compared to those in normal fetal or adult thymi by hybridoma analysis. Results showed a general absence of gene rearrangements typical of the normal fetal thymus in both sets of chimeras. alpha and gamma gene rearrangements in chimeric mice matched normal adult patterns. However, chimeric thymocytes were unique in an unusually low frequency of rearrangements at the delta locus. The use of the bone marrow vs. fetal liver as stem cell sources in chimeric mice did not affect the patterns, indicating that environmental factors played a major role in the molding of gene rearrangement at multiple T cell receptor loci. Interestingly, the chromosomal sequence added an additional influence as homologous chromosomes showed allele-specific rearrangement patterns. We now question whether the unique patterns of rearrangement in irradiated adult thymi may substantially affect developing T cell populations in chimeric animals, particularly with regard to the gamma/delta T cell subset. Further analyses are warranted, both in experimental and clinical settings, regarding ultimate potentials for T cell diversity and function in transplantation recipients.

Alleles↗
PubMed1989

Elevated expression of the interleukin 4 receptor in carcinoma: a target for immunotherapy?

Studies using monoclonal antibody MR6, which is thought to bind to the interleukin-4 growth factor receptor (IL-4R), indicate that IL-4R molecules are upregulated in tumours of epithelial origin and that radiolabelled MR6 is effective as an in vivo tumour imaging agent. Immunohistochemical analysis of a wide range of solid tumours using monoclonal antibody MR6 has demonstrated elevated expression of the IL-4R on a variety of carcinomas. The equivalent normal tissue showed either weak or no expression of this molecule. No other tumours studied were positive. The molecular weight of the receptor on tumour cells was indistinguishable from that on normal tissue. These data raise the possibility that the IL-4R is the product of a novel oncogene such that elevated expression of this growth factor receptor could be involved in the process of carcinogenesis. Monoclonal antibodies to the IL-4R, such as MR6, may therefore be useful reagents not only for diagnosis and immunoscintigraphy, but also for in vivo antibody-guided therapy of epithelial cancers.

Blotting, Western↗