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D J Charron

Publications and source records attributed to D J Charron.

At least 37 records · Page 2Linked to original sources
PubMed1987

Molecular localization to a unique DR beta-chain of the restriction element of an anti-influenza T cell clone.

The DR beta-chains of a panel of DRw13 cells were characterized by two-dimensional polyacrylamide gel electrophoresis in order to identify the molecule bearing the restriction element of a DR-restricted proliferative and cytotoxic T cell clone COT C2 specific for DRw13 and the influenza A virus. Because in different DRw13 haplotypes one DRw13 beta-chain can be associated with other distinct DRw13 beta-chains, such complex associations allowed us to determine the ability of a given DR beta-chain to present the antigen or COT C2. The presence of the DR beta-chain 6B5, and only this chain, is associated with the ability to induce the proliferation of clone COT C2 whatever the second DR beta-chain associated with 6B5 is, namely 6B4 or 6B3. The DRw13 cells that express 6B4 or 6B3 but not 6B5 could not present the antigen to COT C2. Moreover, ILR2, a monoclonal antibody that precipitated 6B5, blocked the proliferation of COT C2, whereas 7.3.19.1, a monoclonal antibody that precipitated only 6B4 and 6B3, could not block the proliferation of this clone. Thus, the DRw13 beta-chain 6B5 appears as the unique class II element that restricts the response of the T cell clone COT C2.

Antibodies, Monoclonal↗
PubMed1987

[Demonstration of new class I antigens in man].

The hypothesis of new class I antigens has been postulated in man, and several antigen systems have been proposed: HT (Gazit), TC (TCA, TCB) (Van Leeuwen). The present study describes a new class I antigenic marker system, expressed selectively on PHA-activated T lymphocytes and on lymphoblastoid B cell lines. These markers correlated at the cellular activation stage, have been called: human activation or HA markers. 7% of the sera from multiparous women present anti-HA antibodies. The definition of class I molecule (dimer 41K - 12K) has been established by a structural analysis of the molecule; the responsible gene, located on the 6th chromosome could be close to the HLA-A gene. The equivalence with the mouse Qa markers is postulated, but remains to be totally demonstrated.

B-Lymphocytes↗
PubMed1986

Biochemistry of HLA-DRw6: evidence for seven distinct haplotypes.

The DRw6 specificity, which has a frequency of 11% in the Caucasian population, cannot be positively defined, since no monospecific allo-antiserum is available. This particular status among DR specificities led us to study the DRw6 haplotypes at the molecular level. We performed 2D-PAGE analysis of HLA-DR molecules in 44 different DRw6 haplotypes. The data were obtained from six homozygous typing cells, eight families informative for the segregation of the DRw6 haplotype, and 15 unrelated donors. Five unique beta-chain electrophoretic patterns were detected, indicating the existence of five structurally distinct DRw6 beta-chains. Each haplotype expresses one or two beta-chains. The different combinations of the DR beta-chains present in a single haplotype allow to characterize seven unique DRw6 haplotypes. In contrast to what has been previously found for DR2 and DR4, there is no DR beta-chain common to all the DRw6 cells. Correlation of the biochemical data with the recent serologic (DRw13 vs DRw14) and cellular (Dw9, Dw18, Dw19) splits of the DRw6 specificity will be discussed.

Antibodies, Monoclonal↗
PubMed1986

A quantitative dot immunobinding assay for human HLA class II antigens using nitrocellulose membrane filters.

A quantitative method for the evaluation of human HLA-DR antigen expression has been developed. Cell membrane proteins were solubilized in Nonidet P-40 or deoxycholic acid detergent and diluted in a Triton X-100 containing sample buffer. The samples were subsequently spotted on a nitrocellulose membrane filter and fixed by immersion in isopropyl alcohol-acetic acid solution. The membrane was saturated in a 5% BSA blocking buffer and sequentially incubated with specific monoclonal anti-HLA-DR antibody, and 125I-labelled protein A. Each spot was then assayed for radioactivity in a gamma scintillation counter. Immunoadsorbant purified HLA-DR antigen was used to standardize the method and a reference dosage curve was established with serial dilutions of the purified HLA-DR antigen. The method permitted the detection of HLA-DR antigens with reproducibility in the ng range, in cellular extracts, physiological and pathological fluids, and in fractions eluted from affinity columns.

Cell Line↗
PubMed1986

Despite lack of monospecific anti-DRw13 sera, a corresponding class II determinant can be defined by a DRw13 restricted anti-influenza virus T cell clone.

The study of a T3+ T4+ T8- human T cell clone COTC2 with both specific proliferative response and cytolytic activity for influenza A virus infected cells reveals that: the restricting element of this clone is strongly associated with DRw13 molecule(s) as seen by the study of a large panel of antigen presenting cells (APC) and by the observation that monoclonal antibodies (MoAb) specific for DR molecules inhibit its proliferative activity while anti-DQ MoAb do not. These results indicate that there exists a DRw13 associated determinant that can be defined at the functional level by COTC2 recognition despite the absence of monospecific anti-DRw13 serum. In contrast to the results found by other groups, the restriction of this DRw13 restricted clone follows the DRw13 serological definition irrespective of the DW type of the APC. These results indicate that the polymorphism of HLA class II molecules can be further defined at the functional level by monoclonal populations of T cells in conjunction with molecular definition.

Antibodies, Monoclonal↗
PubMed1986

Expression of MHC class II and Tac antigens on IL2-activated human T cell clones that can stimulate in MLR, AMLR, PLT and can present antigen.

The expression of interleukin 2 (IL2) receptor and HLA-DR, DQ, and DP antigens on the surface of four diphtheria toxoïd (DT)-specific T lymphocyte clones (TLC) and two TLC specific for an allogeneic EBV-transformed cell line was investigated with the use of monoclonal antibodies (MoAbs) that recognize defined molecules or epitopes. Incubation of a resting TLC with IL2 resulted in a 10- to 30-fold increase in the level of DR, DQ, and Tac antigen expression. On the other hand, incubation of an activated TLC with IL2 decreased for 1 to 6 hr the level of expression of these three antigens. Anti-FA MoAbs did not react with any of the TLC tested suggesting that the expression of DR, DQ, and DP antigens is dissociated on activated TLC. Surface-marker analysis with anti-DR MoAbs indicated that DR epitopes were differently expressed at some activation stages of the TLC. Functional studies showed that activated TLC can stimulate in MLR, AMLR, and PLT. These proliferative responses were inhibited by preincubating the TLC with anti-DR MoAbs suggesting that the stimulatory determinants were predominantly DR molecules. In addition, some TLC can act as antigen presenting cells in DT-specific proliferative responses. These results indicate that MHC class II molecules on activated T lymphocytes may be relevant for the control of specific immunologic responses in vivo.

Antibodies, Monoclonal↗
PubMed1986

Restriction of the in vitro anti-mannan antibody response by HLA-DQ molecules.

In humans, the in vitro antibody response directed towards mannan, a polysaccharide extracted from the cell wall of Candida albicans, has been previously shown to be dependent on the presence of T lymphocytes and monocytes. Evidence is now given for the existence of a genetic restriction governing this response since antibody production is achieved provided that monocytes and T lymphocytes on one side and monocytes and B lymphocytes on the other side are of the same origin. In order to delineate the restriction element governing these interactions, blocking experiments have been designed using well-defined monoclonal antibody, anti-HLA class II molecules. The results clearly indicate that the restriction element belongs to the HLA-DQ molecular series, as shown in T-cell proliferation and antibody production assays in the presence of either T cells or T-cell supernatants. Incubation of isolated cell populations (T, B lymphocytes and monocytes) with the monoclonal antibody have indicated that DQ determinants are involved in the mannan presentation by monocytes to T and B cells. The HLA-DQ mediated restriction of the in vitro immune response to mannan has been observed in all the subjects tested, suggesting that mannan epitopes are preferentially, or even only, recognized in association with an unique group of HLA-class II molecules, namely HLA-DQ.

Antibodies, Monoclonal↗
PubMed1986

New class I in man: serological and molecular characterization.

New class I antigens in linkage disequilibrium with HLA-A antigen are demonstrated in PHA T and EBV preferential target cells using human alloantisera. These new antigens are defined as class I antigens by immunoprecipitation of a 41-12 k dimer. The molecule is shown to be distinct from the HLA-A, -B, -C molecule and in particular from the A3 molecule as in sequential immunoprecipitations, the depletion of the HLA-A, -B, -C molecule or A3 molecule (44-12 k) has no effect on the new molecule (41-12 k). Being present on the PHA T cells and lymphoblast lines, these antigens are considered as new epitopes involved in the the cell activation process.

B-Lymphocytes↗
PubMed1985

Analysis of HLA-DR antigen glycosylation by serial lectin affinity chromatography.

The structure of the N-linked oligosaccharides of HLA-DR molecules from an HLA-DR homozygous B-lymphoblastoid cell line (CA) was characterized by serial lectin affinity analysis. Glycans lectin affinity profile were obtained for the HLA-DR complex and separated alpha- and beta-chains. Two structurally distinct glycosylation patterns were detected for the alpha-chain species, the alpha 1 with high-mannose- and complex-type oligosaccharides and alpha 2 with a complex-type one. In contrast, the beta-chain species contains only complex-type oligosaccharides. Further oligosaccharide heterogeneity is found for each alpha 1-, alpha 2- and beta-chain described. In contrast to murine and guinea-pig Ia antigens, no significant amount of glycopeptides with biantennary structure was found in HLA-DR.

Cell Line↗
PubMed1985

A defect in the regulation of major histocompatibility complex class II gene expression in human HLA-DR negative lymphocytes from patients with combined immunodeficiency syndrome.

Patients with an autosomal recessive combined immunodeficiency are characterized by an HLA negative phenotype of activated T and B lymphocytes. To determine the molecular basis of this syndrome we have studied the biosynthesis of class I and II antigens and the expression of relevant genes in these patients. The synthesis of the HLA A, B, and C heavy chain is markedly decreased, while beta 2 microglobulin is made in normal amounts. Biosynthesis of HLA-DR alpha-chain and beta-chain is abolished in the lymphocytes of these patients and there is a total absence of mRNA for either alpha-chains or beta-chains of HLA-DR. This indicates that the lack of class II antigen on these lymphocytes results from a block in the expression of HLA-DR genes. The Ii-chain, the invariant polypeptide associated intracellularly with HLA-DR, and its mRNA are made in normal amounts. Since the structural genes coding for class II polypeptides do not seem to be affected, the reported genetic defect in the patients concerns the regulation of the expression of HLA-DR genes.

Antigens, Surface↗
PubMed1984

Immunohistochemical study of Ia antigen in the normal and diseased human kidney.

The presence and distribution of Ia antigen in normal human kidneys and biopsy specimens from patients with renal disease were investigated by immunohistochemical techniques using two monoclonal antibodies to the nonpolymorphic determinants of human HLA-DR molecules. Ia antigen was found on the endothelium of glomerular and peritubular capillaries and of veins and vasa recta. Loss of endothelial staining was found in necrotic and sclerotic glomerular and tubulointerstitial lesions. Staining or decreased staining was also not found in the severe proliferative nephritis of systemic lupus erythematosus although endothelial cells could still be identified upon light microscopic examination of the same biopsy specimen. Resting and proliferating cells in mesangial areas did not stain with anti-Ia antibody and extracapillary proliferating cells did not express Ia antigen except for occasional cells in anti-GBM crescentic glomerulonephritis, suggesting that Ia-bearing cells are not involved in mesangial and most extracapillary proliferations in human glomerulonephritis. All clustered mononuclear cells infiltrating the renal interstitium stained with anti-Ia antibody regardless of the type of nephritis where infiltrates occurred.

Antibodies, Monoclonal↗
PubMed1984

Differential inhibition of human antigen-specific T cell clone proliferative responses by distinct monoclonal anti-HLA-DR antibodies.

The inhibition of diphtheria toxoid and varidase-specific T cell clones from a single DR 6/7 donor by eight distinct monoclonal anti-HLA-DR antibodies was tested in proliferative assays. These moAb were selected because they had been previously defined for their ability: 1) to react with Ia molecules; 2) to recognize similar or different epitopes; 3) to share or not share idiotypic specificities. Our results show a distinct inhibition pattern for each clone tested. Furthermore, the various moAb could be classified into three groups according to their inhibitory effect on T cell proliferation. These data suggest: a) an epitopic restriction by class II antigens of antigen-specific human T cell clone proliferation; and b) the recognition of functional epitopes on the human Ia-like antigens by some but not all moAb studied.

Antibodies, Monoclonal↗
PubMed1984

Differential expression of HLA-DR and HLA-DC/DS molecules in a patient with hairy cell leukemia: restoration of HLA-DC/DS expression by (12-0-tetradecanoyl phorbol-13-acetate), 5 azacytidine, and sodium butyrate.

Biosynthesis and molecular structure of major histocompatibility complex (MHC) class II antigens of DR2/DR7 hairy cells were analyzed by two-dimensional polyacrylamide-gel electrophoresis (2D-PAGE). Two anti-human Ia monoclonal antibodies (mAb) were used to immunoprecipitate DR and DR-linked DC/DS molecules. Monoclonal antibody VI 15 C recognizes DR (I-E-like) molecules and CA 2.06 precipitates DR and DR-linked DC/DS (I-A-like) molecules in DR7 allotypes. Studies were performed on a pure population of hairy cells before and after culture with phorbol ester: 12-O-tetradecanoyl phorbol-13-acetate (TPA), 5 azacytidine (5 Aza), sodium butyrate (NA-BU), and phytohemagglutinin (PHA-P). Before any treatment, hairy cells expressed and synthesized DR antigens: DR alpha and beta subunits appeared both qualitatively and quantitatively normal by 2D-PAGE profile. In contrast, the hairy cells failed to express and synthesized any DC/DS molecule. The lack of DC/DS molecular expression was restored after culture in presence of TPA, sodium butyrate, and 5 azacytidine, but not after PHA-P treatment. Differential molecular expression of MHC class II antigens in leukemic cells provides a model to define further discrete stages of hemopoietic differentiation and study the role of these molecules in the cellular interactions occurring during differentiation.

Antibodies, Monoclonal↗
PubMed1984

T-lymphocyte progenitors in man: biochemical characterization of a colony promoting activity (CPA) active on immature precursors.

PHA-stimulated lymphocyte supernatants (P-SUP) containing colony promoting activity (CPA) and interleukin-2 (IL-2) were found to drive T-lymphocyte precursor cells (OKT4-OKT8- blood cells) into colonies of mature T cells in agar. Ammonium sulphate precipitation followed by gel filtration on Sephadex G-75 showed that both IL-2 activity and CPA coeluted in the 21,000 MW fraction. Chromatofocusing on a PBE 94 gel equilibrated between pH 7.4 and 4.2 showed that CPA coeluted with the two main peaks of IL-2 (pI 7.2, pI 6.7). Adsorption of IL-2 activity by more than 97% on different T-cell lines did not completely abolish CPA. These results suggest that other(s) factor(s) with the same biochemical characteristics as IL-2 play a role in the induction of growth and differentiation of immature T-cell precursors.

Cell Differentiation↗
PubMed1983

Biochemical characterization of an invariant polypeptide associated with Ia antigens in human and mouse.

Ii, a 31,000 mol. wt polypeptide chain associated with murine and human Ia antigens was investigated for its labeling pattern, carbohydrate content and structural polymorphism. Two-dimensional gel electrophoretic analysis of tunicamycin treated cells from mouse and human lymphocytes shows that Ii contains two N-linked carbohydrate chains. Ii is a methionine rich polypeptide. Tryptic and chymotryptic two dimensional peptide maps of Ii chain associated with I-A and I-E subregion products are identical. This absence of polymorphism holds true when Ii chain is isolated from different mouse haplotypes. Human Ii chains from different HLA-DR types appear also invariant by peptide map analysis. By molecular weight, carbohydrate content, charge and tryptic and chymotryptic maps criteria, Ii of mouse and human are strikingly homologous.

Animals↗
PubMed1983

Syngeneic anti-idiotypes against monoclonal anti-HLA-DR antibodies: characterization of recurrent idiotopes.

Monoclonal anti-HLA-DR antibody (anti-DR mAb) reactivity was investigated at the idiotypic level; three syngeneic anti-idiotype (Id) sera were raised against three monomorphic anti-DR mAb (206, BM 50, and D 1.12). The syngeneic anti-Id responses exhibited some differences in their intensity and the idiotypic determinants recognized by the three anti-Id sera were localized, at least in part, on the antigen combining site of the respective anti-DR mAb. Idiotype analysis of 24 anti-DR mAb was performed with these anti-Id sera by Id-binding inhibition assays. Idiotypic cross-reactivity was demonstrated for 12 out of the 24 anti-DR mAb, indicating a large degree of idiotypic recurrence. Analysis of the cross-inhibition patterns led us to define at least five sets of recurrent idiotopes: one set cross-reacting with anti-206 Id, the second with both anti-BM 50 and anti-D 1.12 Id, the third with anti-BM 50 Id only, the fourth with anti-D 1.12 Id only, and a fifth set was shared by D 1.12 and NE 4. Eleven monomorphic anti-DR mAb and one polymorphic anti-DR 3 mAb (16.23) did not cross-react with the three anti-Id sera. These results suggest that the mouse antibody response to monomorphic determinants on human Ia antigens is based on a limited number of recurrent idiotopes. In two cases, recurrent idiotopes could be related to a similar anti-DR mAb fine specificity. These anti-Id provide useful reagents to classify and compare anti-DR mAb.

Animals↗