Biomedical subjects

J Theze

Publications and source records attributed to J Theze.

At least 19 recordsLinked to original sources

PubMed1992

Hyper-IgM immunodeficiency syndrome: influence of lymphokines on in vitro maturation of peripheral B cells.

Peripheral B cells from six patients affected with the hyper-IgM immunodeficiency syndrome, characterized by an absence of IgG and IgA in serum with a concomitant elevated level of IgM, were analyzed for phenotypic and functional characteristics. We report that although the membrane antigenic pattern expression was characteristic of mature B cells, B cells from most patients exhibited an impairment in their in vitro response to several lymphokines, such as recombinant interleukin 2 (rIL-2) and low molecular weight B-cell growth factor (BCGF), that induce proliferation of anti-mu-activated B cells. This impairment was also found in response to a lymphokine mixture from a CD2-activated T-cell clone. The decrease in lymphokine-induced B-cell proliferation was accompanied by a low B-cell differentiation, whether patients' B cells were stimulated by the T-cell clone supernatant or rIL-2 and rIL6, lymphokines able to support differentiation of Staphylococcus aureus Cowan I (SAC)-activated B cells. In addition, none of the lymphokines tested were able to induce patients' B cells to switch from IgM-secreting cells to IgG- and IgA-secreting cells. We conclude that this syndrome is associated with a defect in lymphokine-dependent maturation of B lymphocytes, although the T- or the B-cell origin of the defect still cannot be determined.

Antibody-Producing Cells↗

PubMed1992

Molecular area involved in the in-vitro dimerization of the murine p55 IL-2 receptor.

In order to study structure-function relationships of the M(r) 55,000 subunit of the murine IL-2R (p55 IL-2R) by epitope mapping, we have expressed the p55 IL-2R molecule in a cell-free translation system. Under these in vitro conditions, we detected the expected p55 IL-2R polypeptide initiated at Met 1 and, in addition, two internally initiated molecules at Met 64 and Met 105. In this report we describe that from such a mixture, containing three molecular species of p55 IL-2R, mAb 135D5 immunoprecipitated the polypeptide initiated at Met 105 although this N-terminally truncated form of p55 IL-2R does not contain its epitope located between amino acids 72-88. This observation can be taken as a further evidence for the formation of p55 IL-2R dimers. Finally, we identified the region implicated in the formation of p55 IL-2R dimers close to the transmembrane region of the molecule.

Animals↗

PubMed1992

Antibodies of HIV-1 positive subjects and experimentally immunized primates and rodents bind to sequence divergent regions of the third variable domain (V3) of gp120.

Several motifs have been found to be the target of the neutralizing antibody response to HIV, the human immunodeficiency virus. One of the well characterized motifs maps to a loop within the third hypervariable region (V3) of the exterior envelope glycoprotein gp120 at amino acid positions 308-331 and is referred to as the principal neutralizing determinant (PND). The sequence of this V3 loop raises the question of the immunogenicity and the degree of diversity of the antibody response to the PND. We show here that this neutralization-related motif is highly immunogenic in HIV-positive subjects and in experimentally immunized primates and rodents submitted to various anti-HIV immunization regimens. In probing the diversity of the antibody response to PNDs corresponding to 11 HIV sequence-divergent isolates in serum samples of 101 HIV-positive individuals we found that human antibodies exhibit binding affinity to up to nine PND synthetic peptides. This antibody binding was in all cases tested inhibitable by the homologous PND synthetic peptide. We additionally demonstrate that this antibody cross-reactivity towards sequence-divergent PNDs is detectable in the sera of mice and chimpanzees experimentally immunized against a single HIV-1 isolate. Finally, we noticed that there is a hierarchy of reactivity among the various PNDs wherein the synthetic peptide corresponding to the MN isolate was generally the most prominently recognized by antibodies of human, non-human primate, and rodent origins. Based on these findings and on features of the sequences analyzed we suggest that, despite its overall sequence variability, the PND encompasses conserved amino acid positions or epitopes that are the targets of antibodies recognizing sequence-divergent isolates. We also propose that the high positive charge density of the most frequently recognized PNDs and the high antigenicity value of some of their residues are critical to the broad immunoreactivity of this neutralization-related motif.

Acquired Immunodeficiency Syndrome↗

PubMed1992

Monomorphic organization of human diversity (DH) heavy chain variable genes.

While recent evidence indicates that human immunoglobulin heavy chain variable (VH) genes exhibit a high degree of heterogeneity, little is known concerning the polymorphism of the diversity (DH) gene complex. This locus comprises two clusters, major and minor, which are physically linked with the VH locus. In assessing the variability of the human major and minor DH clusters, we found no evidence for a substantial restriction site polymorphism. We also noted that, in contrast to what was found in the Japanese population, the DH1 gene is not deleted in an appreciable proportion of the European population. We propose that, because DH genes impart the critical functions associated with the third complementarity-determining region, the genomic organization of the human DH locus has been evolutionarily conserved through selection pressure mechanisms.

Antibody Diversity↗

PubMed1991

Structure-function study of the p55 subunit of murine IL-2 receptor by epitope mapping.

Using a cell-free translation system we have expressed the Mr 55,000 subunit of the murine IL-2R (p55 IL-2R), which binds IL-2 with low affinity (Kd = 10 nM). Mutants and truncated forms of p55 IL-2R have been used to map the epitopes recognized by three anti-p55 IL-2R mAb: 135D5, 7D4, and 2E4. The mAb 135D5 inhibits IL-2 binding to p55 IL-2R and recognizes an epitope located between amino acids 64 to 125. This epitope can be mimicked by a synthetic peptide corresponding to the region defined by residues 72 to 88. However, the mAb 7D4 and 2E4 do not affect the IL-2 binding to p55 IL-2R. These mAb recognize an epitope of p55 IL-2R lying between residues 125 to 212 that can be mimicked with a peptide corresponding to amino acids 188 to 208. A strong correlation emerged between the experimental results on epitope mapping and predictions of potential antigenicity of murine p55 IL-2R. In addition, we described two internal initiation sites of p55 IL-2R mRNA under the in vitro conditions used leading to the production of significant amounts of N-terminal truncated p55 IL-2R proteins.

Amino Acid Sequence↗

PubMed1991

Probing VH gene-family utilization in human peripheral B cells by in situ hybridization.

Recent studies on the genomic organization of the human Ig VH locus have revealed the presence of an important proportion of VH pseudogenes and a high degree of interspersion among VH gene-family members. The mechanisms of selection of VH genes expressed by differentiating B cells remain to be elucidated. We have made use of RNA-RNA in situ hybridization to probe the repertoire of VH gene-families assembled in peripheral B cells of normal adults. Cells were in vitro activated with mitogens and then hybridized to [35S]-labeled anti-sense RNA probes specific for C mu and C gamma genes, and for the six known human VH gene-families. We found that the numbers of cells expressing C mu and C gamma mRNA were similar to the total numbers of cells expressing members of the six VH gene-families. Therefore, the six known VH gene-families represent essentially the human VH locus. We also found that expression of VH gene-families does not closely correlate with their relative genomic complexity. This apparently biased expression may suggest that in some VH gene-families the ratio of pseudogenes/functional genes is particularly high, and/or that regulatory mechanisms play a major role in shaping the available VH gene repertoire in differentiating B cells.

Antibody Specificity↗

PubMed1991

Concomitant histamine, interleukin 4, and interleukin 6 production by hematopoietic progenitor subsets in response to interleukin 3.

Murine interleukin 3 (IL-3) induces a strong, concomitant increase in histamine, interleukin 6 (IL-6), and interleukin 4 (IL-4) synthesis by progenitor-enriched bone marrow cell populations, whereas interleukin 2 (IL-2) or interferon-gamma (IFN-gamma) are undetectable. This phenomenon is observed between 4 and 12 h after exposure to the growth factor and attains maximal cytokine and histamine levels within 24 and 48 h, respectively. None of these mediators is produced by lymphoid populations such as lymph node cells or by granulocytes. Splenocytes secrete only low histamine and IL-6 levels, in accordance with the lower incidence of progenitors in the spleen, whereas total bone marrow cells generate substantial amounts of the three mediators even before enrichment. Histamine, IL-4-, and IL-6-producing cells copurify with immature cells and cannot be separated from each other throughout the sorting procedures used herein. They are concentrated in the low-density layers (buoyant density 1.069-1.086 g/cm3) of a discontinuous Ficoll gradient (less than 4% of the total bone marrow) together with the majority of hematopoietic progenitors (marrow-repopulating ability [MRA] cells, spleen colony-forming units [CFU-S] day-8 and day-12, granulocyte-macrophage colony-forming units [CFU-GM], and mast cell precursors). Their lightscatter characteristics are those of relatively large, granular cells. They do not belong to the most primitive stem cell subset (MRA and part of CFU-S day-12), but to a population with high mitochondrial activity identified by their important rhodamine retention (colony-forming unit cells [CFU-C], blast cells). In addition, we provide evidence that histamine, IL-4, and IL-6 do not depend on each other for their respective expression. Taken together, our data are consistent with the notion that in certain conditions, immature hematopoietic cells are a potent source of histamine and cytokines.

Animals↗

PubMed1990

Human severe combined immunodeficiency disease: phenotypic and functional characteristics of peripheral B lymphocytes.

Human severe combined immunodeficiency disease (SCID) includes an X-chromosome-linked type characterized by a complete absence of mature T cells, hypogammaglobulinemia but normal or elevated number of B cells, suggesting that the disease results from a block in early T cell differentiation. It has been shown that B cells from obligate carrier women of this disorder exhibit the preferential use of the nonmutant X chromosome as the active X (as shown for T cells), suggesting that the SCID gene product has a direct effect on B cells as well as on T cells. To examine this question, we analyzed the phenotypic and functional characteristics of peripheral B cells from nine infants with SCID. We found a constant absence of spontaneously expressed activation Ag on B cell membrane from all SCID patients tested which contrasts with the phenotypic pattern exhibited by age-matched infants whom all cells bearing surface Ig express the 4F2 Ag and to a lesser extent the transferrin receptor. Concurrently, B cells from SCID patients have a profound impairment in their responses to stimuli that induce in vitro B cell proliferation and differentiation. Although rIL-2 and low-Mr B cell growth factor are potent inducers of proliferation on age-matched infants' B cells, they are poorly efficient in inducing proliferation of anti-mu-activated SCID B cells. This impairment is not related to the resting B cell phenotype of SCID B cells as shown by comparison with normal resting B cells. Furthermore, we observed an apparent block in B cell differentiation inasmuch as neither rIL-2 nor rIL-6 could support SAC-activated SCID B cell differentiation, both lymphokines being very efficient in inducing SAC-activated age-matched infants' B cell or purified resting B cell differentiation. These results suggest that the SCID gene defect has a direct effect on B cells and is required during B cell maturation.

Antigens, CD↗

PubMed1989

Activation by IL-2, but not IL-4, up-regulates the expression of the p55 subunit of the IL-2 receptor on IL-2- and IL-4-dependent T cell lines.

We have investigated the effects of IL-2 and IL-4 on different parameters of T cell activation using three T cell lines. The Th cell line L14 and the cytotoxic T cell line C30.1, both grown in IL-2-containing medium, and a line derived from C30.1 cells (line 1) cultured in IL-4 for a prolonged period were studied. All three cell lines could be activated with IL-2 or IL-4. T cell stimulation by either IL-2- or IL-4-induced identical patterns of cell size enlargement and transferrin receptor expression. However, only IL-2 up-regulated cell-surface expression of the p55 subunit of the IL-2R (p55 IL-2R) as measured by flow cytometry and RIA. This difference was also reflected by the accumulation of soluble p55 IL-2R in the culture medium. No significant increase in expression of membrane or soluble forms of p55 IL-2R was detected after IL-4 stimulation. mAb specific for p55 IL-2R which block IL-2-induced T cell growth did not affect IL-4-mediated T cell proliferation indicating that p55 IL-2R is not involved in IL-4-mediated T cell growth. Analysis of IL-4R expression performed on line 1 using biotinylated IL-4 revealed that IL-4, but not IL-2, is capable of increasing IL-4R expression. Together these results suggest that during IL-2- or IL-4-induced T cell proliferation, each lymphokine specifically up-regulates its own receptor.

Animals↗

PubMed1989

Human B cell activating factor (BCAF): production by a human T cell tumor line.

In a previous study, we demonstrated that supernatants from human T cell clones stimulated by a pair of anti-CD2 monoclonal antibodies cause resting human B cells to become activated and to proliferate in the absence of any other signals. The activity responsible for these effects was shown to be different from already characterized lymphokines and in particular from IL-2 and IL-4, and was named B Cell Activating Factor or BCAF. In this paper, we describe the production of BCAF by a human T cell tumor line T687 after phorbol myristate acetate (PMA) stimulation; this production can be potentiated by phytohemagglutinin (PHA). We further show that the stimulatory phase can be separated from the secretory phase thereby avoiding contamination of BCAF-containing supernatant by PMA and PHA. Supernatants produced under these conditions do not contain either IL-4 or IFN but contain traces of lymphotoxin and 2 to 10 ng/ml of IL-2. The T687 cell line will allow us to obtain a large volume of supernatant for biochemical study and purification of the molecule(s) responsible for BCAF activity.

B-Lymphocytes↗

PubMed1986

Supernatant from a cloned helper T cell stimulates most small resting B cells to undergo increased I-A expression, blastogenesis, and progression through cell cycle.

Helper T cell clone 52.3 supernatant (52.3 SN) was previously shown to be able to stimulate gradient-purified murine resting B cells in the absence of any additional stimulus. However, the proportion of cells that were accounting for the thymidine uptake and the Ig production was unknown. In this paper, we have studied induced changes that can be measured at the single cell level, and have thus determined the frequency of resting B cells that respond to 52.3 SN. Results indicate that 52.3 SN induces an increased I-A expression and a cell size enlargement on virtually all resting B cells. A significant proportion (30%) of these cells later becomes large blasts. Acridine orange staining revealed that in the presence of 52.3 SN a large fraction of the resting B cells undergoes the G0 to G1 transition. Furthermore, 52.3 SN is able to induce at least 20% of the cells to continue through the cell cycle into S phase as indicated by propidium iodide staining of DNA. Finally, a fraction of the 52.3 SN-stimulated cells differentiate to Ig-producing cells. Our present results suggest that resting B cells express functional receptors for some lymphokines and that these lymphokines can act in the absence of membrane Ig occupancy. Our findings further support the existence of a B cell-activating factor acting in a MHC-unrestricted manner and responsible for the entry of resting B cells into cell cycle. The relationship between this factor and other lymphokines is discussed.

Acridine Orange↗

PubMed1985

LPS and specific T cell responses: interleukin 1 (IL 1)-independent amplification of antigen-specific T helper (TH) cell proliferation.

Lipopolysaccharide (LPS) fraction of endotoxin induces a significant potentiation of the antigen-specific proliferative response of T helper (TH) cell lines. This effect was obtained with LPS from different bacterial sources and reproduced with the lipid A moiety of endotoxin. Purified adherent spleen cells used as antigen-presenting cells (APC) support this LPS-enhanced TH cell proliferation. In addition, the effect of endotoxin on specific TH cell responses was found to be absolutely dependent on the interaction between TH lymphocytes and APC through antigen-specific recognition. Thus, it was not observed in the absence of specific antigen or when monoclonal antibodies against class II MHC products or against L3T4 antigens were used to inhibit the T cell-APC interaction. Similarly, it was found that APC from the B6.CH-2bm12 mutant do not support the LPS-mediated enhancing effect. Furthermore, interleukin 1 (IL 1) appears not to be involved in LPS-mediated enhancement, and this effect is not reproduced by muramyl dipeptide (MDP)-mediated activation of APC.

Adjuvants, Immunologic↗

PubMed1978

Idiotypic analysis of anti-GAT antibodies. I. Presence of common idiotypic specificities in both responder and nonresponder mice.

The synthetic terpolymer of L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) induced anti-GAT antibodies in D1.LP mice. Some of these antibodies shared common idiotypic specificities. The interaction between idiotypic antibody and anti-idiotypic antiserum was specifically inhibited by GAT and the closely related polymer of L-glutamic acid and L-tyrosine (GT) but not by the copolymer of L-glutamic acid and L-alanine (GA). The binding of labeled GAT by the anti-GAT antibodies was also specifically inhibited by the anti-idiotypic antiserum. These results indicated a close association of idiotypic determinants with the antibody-combining sites. Furthermore, such active site-related common idiotypic specificities were found in individual sera of both responder mice (D1.LP) and nonresponder mice (DBA/1) immunized with GAT and GAT-MBSA, respectively, indicating that both responder and nonresponder mice carry B cells with common clonotypes.

Alanine↗

PubMed1978

Modulation of immune responses by suppressor T cells.

The activity of suppressor T cells has been demonstrated in almost every phase of the immune response. These regulatory cells modulate both humoral and cell-mediated immunity utilizing antigen-specific and nonspecific mechanisms. For comparative purposes two murine models are described, the nonspecific suppressor T cell stimulated by the mitogen concanavalin A and the antigen-specific suppressor T cell stimulated by injection of the synthetic terpolymer acid 60-L-alanine30-L-tyrosine10 (GAT) in nonresponder mice. These two T cells are similar to expression of Ly alloantigens, ability to inhibit antibody responses, and the mediation of suppression, at least in part, by soluble products. However, differences in radio-resistance and antigenic specificity of the suppressor T cells, as well as differences in molecular characteristics of the soluble factors and their targets suggest that these T cells regulate the immune response by different mechanisms. The relationship of these two suppressor T cells to other nonspecific and antigen-specific suppressor T cells is discussed.

Alanine↗

PubMed1978

Antigen-specific T cell-mediated suppression. II. In vitro induction by I-J-coded L-glutamic acid50-L-tyrosine50 (GT)-specific T cell suppressor factor (GT-T8F) of suppressor T cells (T82) bearing distinct I-J determinants.

The induction of new suppressor T cells (Ts2) by suppressive extracts (TsF) from L-glutamic acid50L-tyrosine50 (GT) nonresponder mice was examined. Incubation of normal spleen cells with allogeneic GT-TsF for 2 days in vitro led to the generation of Ts2 cells able to suppress subsequent responses to the immunogen GT-methylated bovine serum albumin (GT-MBSA) in vivo. This induction occurred efficiently when TsF donor and target cells differed at all of H-2, including the I-J subregion. B10.BR (H-2k) GT-TsF, adsorbed on, then acid eluted from GT-Sepharose and anti-I-Jk [B10.A (3R) anti-B10.A (5R)]-Sepharose in a sequential fashion could induce BALB/c (H-2d) spleen cells to become Ts2 only if nanogram quantities of GT were added to the purified GT-TsF. This indicates a requirement for a molecule or molecular complex possessing both I-J determinants and antigen (GT)-binding specificity, together with GT itself, for Ts2 induction. The induced Ts2 are I-J+, since their function can be eliminated by treatment with anti-I-Jk plus C. These I-J determinants are coded for by the precursor of the Ts2 and do not represent passively adsorbed, I-J coded TsF, since anti-Ijk antiserum [(3R X DBA/2)F1 anti-5R] which cannot recognize the BALB/c (I-Jd) TsF used for induction still eliminates the activity of induced A/J (I-Jk) Ts2. These data provide further evidence for and information about the minimum of two T cells involved in antigen-specific suppressor T cell systems.

Animals↗

PubMed1977

Immunosuppressive factor(s) extracted from lymphoid cells of nonresponder mice primed with L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) III. Immunochemical properties of the GAT-specific suppressive factor.

The GAT-specific suppressor T-cell factor (GAT-TsF) extracted from lymphoid cells from GAT-primed, nonresponder DBA/1 mice has been partially characterized. It is a protein that has affinity for GAT and determinants encoded by the I region of the H-2 complex. On the basis of specificity and avidity, GAT-TsF resembles anti-GAT-MBSA antibodies produced by DBA/1 mice in spite of the fact that it is too small to be classical antibody and has no constant-region determinants of heavy or light chains. Further, GAT or a fragment of GAT is associated with the GAT-TsF. GAT-TsF has been partially purified from the crude extract by absorption to GAT-Sepharose and elution with 0.4 to 0.6 KCl. GAT-TsF purified on the basis of its affinity for GAT bears I-region determinants but not detectable GAT or GAT fragment.

Animals↗

PubMed1975

Evolution of biosynthetic pathways: immunological approach.

Through the use of specific immunoadsorbent columns, it is shown that Escherichia coli aspartokinase I-homoserine dehydrogenase I, aspartokinase II-homoserine dehydrogenase II, aspartokinase III, and homoserine kinase, enzymes involved in the same complex biosynthetic pathway, share antigenic determinants. This raises the question of a common origin for the four cibtenoirart kinases. (Aspartate kinase or ATP:L aspartate 4-phosphotransferase, EC 2.7.2.4; homoserine dehydrogenase or Lhomoserine:NADP oxidoreductase, EC 1.1.1.3; homoserine kinase or ATP:L-homoserine O-phosphotransferase, EC 2.7.1.39.)

Alcohol Oxidoreductases↗

PubMedDate not supplied

Induction of mouse p55 interleukin-2 receptor gene expression by IL-2 and IL-4 and characterization of its transcription initiation sites.

Two murine T cell lines (C30.1 and Line 1) were used to study the expression of the p55 interleukin-2 receptor gene. C30.1 is an IL-2-dependent T cell line that can be stimulated for a short period of time by IL-4. Line 1 cells are propagated in IL-4 but they also proliferate in response to IL-2. In both cell lines stimulation by IL-2 leads to a strong induction of p55 IL-2 receptor mRNA while stimulation by IL-4 leads only to a very moderate increase in expression of this mRNA. The induction of p55 IL-2 receptor mRNA by IL-4 is comparable to that of beta-actin mRNA. These data confirm that IL-2 upregulates p55 IL-2 receptor gene expression while IL-4, which also activates T cells, does not lead to specific induction of this gene. We have also determined the transcription initiation sites utilized by the p55 IL-2 receptor gene in C30.1 and Line 1 cells. Seven sites were identified, one of which predominates. Resting cells, or cells stimulated with IL-2 or IL-4, display the same pattern of transcription site utilization.

Animals↗