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E de Vries

Publications and source records attributed to E de Vries.

At least 19 recordsLinked to original sources
PubMed1992

T cell receptor-alpha beta lacking the beta-chain V domain can be expressed at the cell surface but prohibits T cell maturation.

A TCR-beta gene lacking V domain sequences (delta V-TCR-beta) was inserted into the germline of mice. Expression of the transgene inhibited endogenous TCR-beta, but not TCR-alpha gene rearrangement and expression. The mutated TCR-beta gene affected alpha beta T cell development: the common thymocyte pool was normal in cell number, with cells expressing CD4 and CD8, but the mature, "CD3bright" population expressing either CD4 or CD8 molecules was reduced by 90%. To help understand these effects on TCR-beta gene rearrangement and T cell development, biosynthesis of the delta V-TCR-beta protein was analyzed in a tumor cell line derived from a transgenic mouse. Despite absence of the V domain, the delta V-TCR-beta chain paired with endogenous TCR-alpha chains and assembled with CD3 gamma, -delta, -epsilon, and -zeta components in the endoplasmatic reticulum, followed by transport through the Golgi complex to the plasma membrane. Therefore, assembly of the complex, and even cell surface expression, may be relevant for allelic exclusion of the TCR-beta gene. In the common thymocyte population, the CD3 components, endogenous TCR-alpha, and the delta V-TCR-beta gene product were expressed at the RNA level, but endogenous TCR-beta was not. The TCR-alpha delta beta/CD3 complex was present at the cell surface at low levels and was functional in terms of anti-CD3-induced Ca2+ mobilization. The observed arrest of alpha beta T cell development at the CD4+8+ thymocyte stage indicates that ligand recognition by the TCR, with contribution of the beta-chain V domain, is not required for transition of CD4-8- thymocytes to the CD4+8+ phenotype, but necessary for entry into the "single positive," CD3bright differentiation stage.

Animals↗
PubMed1991

DNA polymerase delta: gene sequences from Plasmodium falciparum indicate that this enzyme is more highly conserved than DNA polymerase alpha.

Genes encoding proteins homologous to the catalytic subunits of DNA polymerase alpha and delta have been cloned from the human malaria parasite Plasmodium falciparum. These are among the first cellular replicative DNA polymerase genes to be cloned and their sequences allow us to make new statements about the relative degrees of conservation of these two enzymes. The most important finding was that P. falciparum Pol delta showed considerable homology to the only other Pol delta enzyme for which published sequence is available, that of S. cerevisiae, displaying an overall amino acid identity of 45% and identity over a highly conserved central region of 59%. In contrast, the level of identity shown over the equivalent central region of Pol alpha between the P. falciparum and S. cerevisiae sequences is only 32%. The sequence data also allowed us to examine the degree of conservation in putative exonuclease domains of Pol delta. The Pol delta gene of P. falciparum maps to chromosome 10 and evidence is presented for the presence of different sized Pol delta mRNA's in the asexual and sexual erythrocytic stages of parasite development.

Amino Acid Sequence↗
PubMed1991

Purification and characterization of DNA polymerases from Plasmodium berghei.

DNA polymerases from the malaria parasite Plasmodium berghei were purified more than 50-fold. Several distinct enzymatic activities were isolated that could be distinguished by the use of various specific DNA polymerase inhibitors. In particular, subdivision into an aphidicolin-sensitive and an aphidicolin-resistant group was possible. Further analysis allowed a better comparison with host DNA polymerases and indicated that one aphidicolin-sensitive DNA polymerase resembled DNA polymerase alpha displaying processive DNA synthesis and using RNA primers, whereas another aphidicolin-sensitive DNA polymerase was distributive and only used DNA primers. Marked differences from the host enzymes do exist, however, such as insensitivity to BuPdGTP. Another P. berghei DNA polymerase was isolated that showed characteristics of a DNA polymerase beta-like enzyme, but which differed from host DNA polymerase beta in its insensitivity to dideoxynucleotides.

Animals↗
PubMed1991

Inhibition of the growth of Plasmodium falciparum and Plasmodium berghei by the DNA polymerase inhibitor HPMPA.

The acyclic adenosine analogue (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine [HPMPA] belongs to a class of nucleoside analogues originally described as having potent activity against a broad spectrum of DNA viruses. We examined the effects of this class of drugs on the growth of cultured Plasmodium falciparum. Strong inhibition was observed by HPMPA (ID50 = 47 nM) at concentrations more than 1000-fold less than the cytotoxic dose for human cells. 3-deaza-HPMPA was even more strongly inhibitory (ID50 = 8 nM), whereas several other acyclic nucleosides were not effective. In mice infected with Plasmodium berghei, increase of parasitaemia can be blocked for 4-6 days by a single injection of HPMPA. Repeated drug administration blocks parasite growth for prolonged periods at doses that are clinically feasible. We also determined the inhibition of several purified Plasmodium DNA polymerases by diphosphorylated HPMPA (HPMPApp). DNA polymerase alpha-like enzymes of P. falciparum and P. berghei are inhibited with an IC50 = 40 microM and a gamma-like DNA polymerase from P. falciparum is even 40-fold more sensitive to the drug. The inhibition by HPMPApp is competitive with dATP, strongly suggesting that Plasmodium DNA polymerases are targets for this class of nucleotide analogue.

Adenine↗
PubMed1990

BMA031, a monoclonal antibody suited to identify the T-cell receptor alpha beta/CD3 complex on viable human T lymphocytes in normal and disease states.

Two types of T lymphocytes can be discriminated on the basis of expression of either the classical T-cell receptor (TCR) alpha beta or the more recently identified TCR gamma delta. Whereas TCR alpha beta + lymphocytes are known to respond to recognition of antigen in the context of major histocompatibility complex molecules by proliferation, lymphokine secretion, and/or cytotoxicity, the potential ligand specificities and functions of TCR gamma delta + cells have not been completely unraveled. Antibodies specific for either receptor type are important tools to elucidate the role TCR gamma delta + cells play in the immune system. They can be used to quantify TCR gamma delta + cells and TCR alpha beta + cells in normal and disease states, to isolate both T-cell subsets, and to perform in vitro functional assays. Only few antibodies reactive with common determinants on either TCR alpha beta or TCR gamma delta are available. Generally, the monoclonal antibody (mAb) WT31 is used for definition of viable human TCR alpha beta + cells. However, WT31 has recently been shown to cross-react with TCR gamma delta. We describe an mAb, BMA031, that combines the unique features of reactivity with intact viable cells and true specificity for a common determinant on the TCR alpha beta/CD3 complex. Its performance in immunofluorescence staining and immunochemistry has been compared with that of WT31 and anti-TCR gamma delta mAbs, using TCR alpha beta and TCR gamma delta expressing cells isolated from blood and bone marrow of healthy individuals and immunodeficient patients.

Animals↗
PubMed1990

Characterization of the dermal infiltrates in Jessner's lymphocytic infiltrate of the skin, polymorphous light eruption and cutaneous lupus erythematosus: differential diagnostic and pathogenetic aspects.

In the present study a comparative immunohistochemical study was performed on skin biopsies from of patients with Jessner's lymphocytic infiltration of the skin (LIS), polymorphous light eruption (PLE), discoid lupus erythematosus (DLE) and subacute cutaneous lupus erythematosus (SCLE) using a large panel of monoclonal antibodies against T cell differentiation antigens (CD3, CD4, CD8), immunoregulatory T cell subsets (CD7, 4B4, 2H4, Leu 8), B cells (CD22), activated cells CD25, OKT9, HLA-DR), Langerhans cells (CD1) and macrophages (Leu-M5). The results showed many similarities between LIS and PLE. The most important differences between these conditions and CDLE/SCLE were the high proportions of cells reactive with monoclonal antibody Leu-8 and the absence of T cells expressing HLA-DR antigens in LIS and PLE, suggesting absence of local T cell activation in these conditions. The differential diagnostic and pathogenetic aspects of these findings will be discussed.

Antibodies, Monoclonal↗
PubMed1989

HeLa nuclear protein recognizing DNA termini and translocating on DNA forming a regular DNA-multimeric protein complex.

Employing an exonuclease III protection assay we detected a protein in crude HeLa nuclear extracts binding, with apparent sequence specificity, to molecular ends of adenovirus type 2 (Ad2) DNA. This protein, designated nuclear factor IV (NFIV), was purified to homogeneity and was shown to be a hetero-dimer of 72,000 and 84,000 Mr. Binding to terminal Ad2 sequences was strongly enhanced by the presence of either of the sequence-specific DNA-binding proteins nuclear factor I and nuclear factor III. These proteins appeared to function as blockades for translocation of NFIV on DNA, thus producing apparent sequence specificity. In the absence of such a blockade, NFIV moved freely, without energy input, on any double-stranded DNA forming a regular DNA-multimeric protein complex as shown by methidiumpropyl EDTA footprinting and electron microscopy. Binding is completely dependent upon the presence of molecular ends. Evidence was obtained for a two-step mechanism in which termini are recognized by NFIV and used as a starting point for subsequent translocation. The possible functions of the protein in adenovirus DNA replication and in cellular processes requiring DNA termini are discussed.

Base Sequence↗
PubMed1989

Potentiation of the stimulatory capacity of pokeweed mitogen via its binding to autologous erythrocytes.

The effect of human erythrocytes (E) on blastogenesis and immunoglobulin (Ig) production induced by pokeweed mitogen (PWM) in cultures of human peripheral blood mononuclear cells (PBMC) was investigated. The stimulation of PBMC with PWM was markedly enhanced in the presence of E, and PWM bound to E, followed by thorough washing (E-PWM), was even more effective in inducing blast cell formation and Ig production. Blast cell responses after stimulation with E-PWM were on average two times higher than those seen after stimulation with comparable dilutions of fluid-phase PWM. The PWM that remained in solution after incubation with E (Sup E-PWM) had little mitogenic capacity and inhibited the blast cell response induced by fluid-phase PWM. Transwell culture experiments demonstrated that the enhancement of the blast cell response of PBMC by E-PWM could be induced by PWM that was released from E-PWM, whereas the enhancement of Ig production was found to be dependent on the presence of PWM on E. Both for blast cell formation and Ig production, it was found that the enhanced stimulation with E-PWM depended on the presence of monocytes.

Erythrocytes↗
PubMed1988

Distinct molecular forms of human T cell receptor gamma/delta detected on viable T cells by a monoclonal antibody.

A second type of TCR molecule has been identified on human and murine T lymphocytes, which involves the protein products of the gamma and delta genes. T lymphocytes bearing this receptor may constitute a separate cell lineage with a distinct immune function. We have produced an mAb, which specifically detects human TCR-gamma/delta in native as well as denatured states, this in contrast to previously used anti-gamma chain peptide sera, which only reacted with denatured protein. The receptor occurs in different molecular forms, with or without interchain disulphide bonds, in which a delta chain may or may not be detected by cell surface iodination. The mAb is reactive with all these receptor forms. Therefore, this antibody could be used to determine the expression of TCR-gamma/delta on viable human T lymphocytes. In normal individuals, TCR-gamma/delta was found on a subset composing 2-7% of CD3+ lymphocytes in peripheral blood and 0.1-1.0% in thymus. The majority of these cells do not express the CD4 or CD8 antigens, although a significant percentage of CD8+ cells was found. TCR-gamma/delta+ cells in peripheral blood are resting lymphocytes, as judged by ultrastructural analysis. T cell clones with different receptor types can display MHC-nonrestricted cytolytic activity, which is shown to be induced by the culture conditions, most likely by growth factors such as IL-2. This strongly suggests that TCR-gamma/delta does not play a role in target cell recognition in MHC-nonrestricted cytotoxicity. The anti-TCR-gamma/delta antibody can specifically induce cytotoxic activity in clones expressing the receptor, but in addition inhibit growth factor induced cytotoxicity, which indicates a regulatory role of the TCR-gamma/delta/CD3 complex in MHC-nonrestricted cytotoxicity.

Adult↗
PubMed1988

Human parvovirus B19 DNA in synovial fluid.

We describe a 33-year-old woman with a serologically proven human parvovirus B19 infection, who developed synovitis. Using a dot-blot hybridization technique, we detected B19 DNA in her synovial fluid. To our knowledge, this is the first report of the isolation of B19 from synovial fluid.

Adult↗
PubMed1988

Anti-pokeweed mitogen antiserum inhibits and enhances blastogenesis of mononuclear cells induced by pokeweed mitogen.

The interaction between pokeweed mitogen (PWM) and peripheral blood mononuclear cells (PBMC) was investigated using rabbit anti-PWM antiserum (anti-PWM) and 125I-PWM. Incubation of PBMC with PWM in the presence of anti-PWM resulted in an inhibition of the mitogenic effect of PWM. Anti-PWM predominantly blocked the interaction of PWM with monocytes, which is essential for optimal stimulation of lymphoid cells with PWM. Addition of anti-PWM to PBMC at several time-points after incubation with PWM showed inhibition of mitogenic activity when anti-PWM was added within 8 hours. However, enhancement of PWM-induced blast cell formation was found when anti-PWM was added after 48 hours. Further analysis revealed that the inhibition of PWM stimulation was mediated by the F(ab')2 part of anti-PWM IgG. On the other hand F(ab')2-anti-PWM was not able to enhance the effect of PWM. Incubation of PBMC with 125I-PWM and anti-PWM simultaneously, decreased the binding of PWM to both lymphocytes and monocytes. In contrast, addition of anti-PWM 48 hours after the incubation of PBMC with PWM resulted in an increased binding of PWM to monocytes. These results show that anti-PWM can modulate the lymphocyte reaction to PWM and suggest two possible mechanisms by which PWM can stimulate PBMC, both of which are dependent on the interaction of PWM with monocytes.

Antibodies↗
PubMed1988

Characteristics of the mitogenic activity found in the supernatant of pokeweed mitogen stimulated human mononuclear cells.

Human peripheral blood mononuclear cells were stimulated with pokeweed mitogen (PWM), washed, and cultured in fresh mitogen-free culture medium; a second set of peripheral blood mononuclear cells was used to assess the mitogenic activity of supernatants of these cultures. The effects of this stimulation resembled those of a normal PWM stimulation, including the formation of blast cells, proliferation of lymphoid cells, and immunoglobulin synthesis. Our findings led us to perform experiments to investigate the nature of this mitogenic factor. The molecular weight of the mitogenic activity was found in the region of 700 kD. Additional experiments indicated that human alpha 2-macroglobulin was not responsible for the high molecular weight of the mitogenic factor. Protein digestion or precipitation with trichloroacetic acid only partially abolished the mitogenicity of the mitogenic supernatant. Comparison of the molecular weight of the mitogenic factor with that of the PWM in culture medium showed that the mitogenic activity in the supernatants could be caused by PWM associated with a high molecular weight component.

B-Lymphocytes↗
PubMed1988

Effects of anti-rheumatic drugs on in vitro mitogenic stimulation of peripheral blood mononuclear cells.

The efficacy of bromocriptine, chloroquine, and Cs was quantitated in an in vitro system, with the use of mitogen-stimulated human PBMC. A concentration-dependent effect was found for each drug. Based on counts of blast cells, Cs was roughly 70 times more effective than either bromocriptine or chloroquine. Besides quantitative comparison of the effect of the drugs, the in vitro system permits conclusions concerning drug combinations. The effect of the combination of bromocriptine and Cs was equal to the expected effects of the separate drugs. However, the combined effect of chloroquine and Cs exceeded the sum of the effects of the individual drugs, which indicates synergy, not addition.

Arthritis, Rheumatoid↗
PubMed1987

Incorporation of 5-bromodeoxycytidine in the adenovirus 2 replication origin interferes with nuclear factor 1 binding.

We have studied the binding of nuclear factor 1 (NFI), a human sequence-specific DNA-binding protein, to a DNA fragment substituted in vitro with 5-bromodeoxycytidine (5-BrdC). Even at low substitution grades binding of NFI to its recognition sequence was considerably lower than with the unsubstituted control fragment. We developed a procedure to cleave substituted DNA specifically at a BrdC residue and searched for contacts between NFI and 5-BrdC residues by an interference assay. Surprisingly, no specific contacts were found in or near the recognition sequence. It appeared instead that interference was inversely related to the distance of a 5-BrdC residue from the NFI binding site. Models to explain these results, including a possible sliding mechanism, are discussed.

Adenoviridae↗