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D S Pisetsky

Publications and source records attributed to D S Pisetsky.

At least 109 records · Page 6Linked to original sources
PubMed1993

Stimulation of in vitro proliferation of murine lymphocytes by synthetic oligodeoxynucleotides.

To elucidate the properties of mitogenic nucleic acids, the ability of oligodeoxynucleotides to stimulate the in vitro proliferation of murine lymphocytes was investigated. The compounds tested were a series of oligodeoxynucleotides, synthesized with either phosphodiester or phosphorothioate chemistry and containing (dG) and (dC) alone or together. Among oligodeoxynucleotides tested, phosphorothioates were more active than phosphodiesters and stimulated thymidine incorporation under the same conditions as mitogenic non-mammalian DNA. Mitogenesis was unaffected by depletion of T cells, suggesting B cells as the predominant cell type stimulated. These results indicate that mitogenic nucleic acids need not have an extended polymeric structure and raise the possibility that antisense compounds have immunologic activity, at least in animal models.

Animals↗
PubMed1993

Autoantibodies and their significance.

In systemic lupus erythematosus, autoantibodies have structural features that indicate in vivo selection by a T cell-dependent, antigen-driven process. The B-cell component of these responses resembles a conventional antibody response, whereas the T-cell component may involve diverse stimulatory mechanisms and levels of regulatory control. Characterizing T-cell epitopes of autoantigens has been difficult because these molecules are ubiquitous and exist inside the cells as multicomponent, macromolecular complexes. Autoantibodies can mediate disease manifestations by various mechanisms, with variable region structures determining the pattern and severity of tissue injury.

Animals↗
PubMed1993

Effect of sex on the induction of anti-DNA antibodies in normal mice immunized with bacterial DNA.

Immunization of normal mice with bacterial DNA elicits a significant IgG anti-DNA response and has been explored as a model of systemic lupus erythematosus. To determine whether this induced response is influenced by sex, we have measured anti-DNA levels in normal male and female BALB/c mice immunized with single stranded DNA from E. coli as complexes with methylated bovine serum albumin (mBSA) in adjuvant. By ELISA assays, anti-DNA levels of immunized females were approximately 16-fold higher than those of immunized males; levels of antibodies to the mBSA carrier were similar, however. The antibodies from females and males showed a similar degree of cross-reactivity when assayed using other natural and synthetic DNA antigens, including mammalian DNA. These findings suggest the potentiation of anti-DNA production in females by antigen-specific mechanisms and provide further evidence that immunization with bacterial DNA replicates features of autoantibody production in SLE.

Animals↗
PubMed1993

The effects of nonsteroidal antiinflammatory drug therapy in early rheumatoid arthritis on serum levels of soluble interleukin 2 receptor, CD4, and CD8.

OBJECTIVE: Cell surface molecules can be shed by activated T lymphocytes and measured in serum to assess in vivo T cell activation. To evaluate the relationship between these serum markers and disease activity in rheumatoid arthritis (RA), we determined levels of soluble interleukin 2 receptor (sIL-2R), CD4 (sCD4), and CD8 (sCD8) in sera from a well characterized group of 26 patients with active RA treated with a nonsteroidal antiinflammatory drug (NSAID) alone. METHODS: A retrospective, blinded determination of sIL-2R, sCD4, and sCD8 levels in serum samples from patients with early, active RA participating in 2 trials of NSAID therapy. Commercially available enzyme linked immunosorbent assays were employed. Data analysis included nonparametric techniques and correction for multiple comparisons. RESULTS: The patients with RA had significantly elevated levels of sIL-2R at baseline compared with age matched healthy controls. During NSAID therapy, mean sIL-2R levels among responders decreased to lower levels while nonresponder levels increased, although these trends did not reach statistical significance. Patients with RA did not differ from controls in baseline measures of serum sCD4 or sCD8 levels. Moreover, the serum sIL-2R, sCD4, and sCD8 levels among patients did not vary significantly from their baseline measures during NSAID therapy, irrespective of response. CONCLUSION: Our results suggest that elevated levels of serum sIL-2R in early RA likely reflect generalized immune system activation, not always associated with elevated serum sCD4 or sCD8 levels or varying with other measures of disease activity in RA.

Adult↗
PubMed1993

Characterization of glomerular thromboxane receptors in murine lupus nephritis.

Renal thromboxane (Tx) production is increased in the MRL-lpr murine model of lupus nephritis. To investigate the relationship between increased Tx production and number and affinity of Tx receptors, we measured binding of the Tx receptor antagonist [3H][SQ295481S-1 alpha,2 beta(5Z),3 beta,4 alpha]-7-(3-((2-((phenyl- amino)-carbonyl)hydrozino)methyl)-7-oxabicyclo-(2.2.1)heptan -2-yl)-5-heptenoic acid in glomerular preparations from MRL-lpr mice and both MRL(-)+/+ and LG/J controls. Renal Tx binding was first characterized in normal LG/J mice. In these animals, glomerular binding was specific, saturable and reversible. Scatchard analysis revealed a single class of high-affinity binding sites. We next evaluated Tx production and binding in 12- and 16-week-old MRL-lpr mice and MRL(-)+/+ controls. To assess renal Tx production, excretion of TxB2 was measured in urine. Urinary TxB2 was increased in MRL-lpr mice at 16 weeks of age. This increase in urinary TxB2 was associated with a reduction in density of glomerular Tx binding sites compared to either 12-week-old MRL-lpr mice or MRL(-)+/+ controls. Ligand binding affinity was similar in all groups. To investigate if this alteration in binding was specific for Tx, glomerular binding of [3H]angiotensin II was measured. In MRL-lpr mice, the number and affinity of glomerular angiotensin binding sites were similar at 12 and 16 weeks of age. Thus, in this murine model of lupus nephritis, enhanced renal Tx production is temporally associated with a decrease in glomerular Tx binding sites without a change in receptor affinity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Genetic analysis of MRL-lpr mice: relationship of the Fas apoptosis gene to disease manifestations and renal disease-modifying loci.

In MRL mice, the mostly recessive lpr mutation results in both the accumulation of CD4-, CD8-, CD3+ T cells in lymphoid tissue and many features of generalized autoimmune disease, including immune complex glomerulonephritis. To positionally clone the lpr mutation and analyze the effects of background genes, backcross offspring were examined from the cross: (MRL/MpJ-lpr x CAST/Ei)F1 x MRL/MpJ-lpr. The lpr gene was found to be closely linked to a mouse chromosome 19 marker defined by a variation of a Fas gene restriction fragment. Our results identified differences in RNA expression and differences in the genomic organization of the Fas gene between normal and lpr mice, and confirm the recent report that a mutation in the Fas apoptosis gene is the lpr mutation. However, our results also indicate that the Fas gene is expressed in spleen cells from normal mice, and spleen and lymph node cells from mice with a second mutation at the lpr locus (lprcg). Together these results suggest that altered Fas transcription results in the failure of lymphocytes to undergo programmed cell death and may lead to an altered immune cell repertoire. This mechanism may explain certain central and peripheral defects in tolerance that are present in autoimmune disease. The current study also demonstrates the profound effect of background genes on the degree of nephritis, lymphadenopathy, and anti-DNA antibody production. Of major note, our studies suggest the identification of chromosomal positions for genes that modify nephritis. Analysis of the backcross mice for markers covering most of the mouse genome suggests that over 50% of the variance in renal disease is attributable to quantitative trait loci on mouse chromosomes 7 and 12. Moreover, this study provides a model for dissecting the complex genetic interactions that result in manifestations of autoimmune disease.

Animals↗
PubMed1992

Analysis of the expression of CD5 by human B cells and correlation with functional activity.

B cells expressing the CD5 marker in the mouse have been suggested to be a separate lineage and a major source of autoantibody production. In man, this relationship is less clear. Studies were therefore undertaken to determine whether human CD5+ B cells represent a distinct lineage of cells that differ in patterns of antibody production from CD5- B cells. In normal B cell populations, CD5 was expressed by a mean of 24.0 +/- 2.8% (n = 10) of CD20+ B cells. Of note, an increased frequency of CD5+ B cells was not found in patients with systemic lupus erythematosus (mean of 17.9 +/- 2.8%, n = 16). Analyzing CD5+ B cells for cell membrane Ig isotype expression demonstrated similar frequencies of IgG and IgA expressing cells as were found on the CD5- B cell population, although the frequency of IgM+ cells was slightly increased. Incubation of CD20+ B cells with phorbol myristate acetate (PMA) for 72 hr increased the frequency of CD5 expressing B cells by more than threefold. CD5 expression was also increased by coculture with anti-CD3-activated T cells and most markedly by simultaneous stimulation with both PMA- and anti-CD3-activated T cells (greater than 50% positive). Analysis of CD5- B cells clearly indicated that stimulation with PMA or anti-CD3-activated T cells induced the majority to become CD5+ transiently. Functional analysis of Ig production by CD5+ and CD5- B cells stimulated with anti-CD3-activated T cells indicated that both populations in normals produced IgM and a variety of autoantibodies in comparable amounts, whereas the CD5- B cells produced greater quantities of IgG. B cells were activated with anti-CD3-stimulated T cells followed by separation into CD5+ and CD5- populations. The largest amount of Ig was produced by CD5- B cells that were induced to express CD5, although all populations produced some Ig. These data suggest that CD5 behaves as an activation marker on human B cells rather than as a marker for a distinct lineage of cells. Moreover, CD5 expression does not appear to identify a population of resting B cells with a greater capacity to produce antibodies to DNA or other autoantibodies.

Antibody Formation↗
PubMed1992

Patterns of heavy and light chain utilization in the antibody response to single-stranded bacterial DNA in normal human subjects and patients with systemic lupus erythematosus.

Although anti-DNA antibodies are generally considered to be specific markers for systemic lupus erythematosus (SLE), antibodies binding DNA from certain bacterial species can be found in the sera of normal subjects. To characterize the immunochemical properties of these antibodies, the IgG subclass and light chain profile of antibodies to single-stranded micrococcal DNA (MC DNA) in the sera of normal subjects and patients with SLE was determined. The anti-MC DNA response in normal sera was predominantly of the IgG2 subclass with a marked predominance of kappa light chains. In contrast, anti-MC DNA antibodies in SLE sera exhibited all IgG subclasses with a predominance of the IgG1 subclass and both kappa and lambda light chains were represented. These results suggest that antibodies to bacterial DNA in the sera of normal subjects and patients with SLE differ in patterns of immunoglobulin gene expression; the restricted response of normal subjects may be related to the binding to a discrete DNA determinant.

Antibody Formation↗
PubMed1992

Effect of anti-CD4 antibody treatment on inflammatory arthritis in MRL-lpr/lpr mice.

MRL-lpr/lpr mice develop an inflammatory arthritis in association with other manifestations of autoimmunity. Although a variety of immune cell disturbances have been described in these mice, the relationship of these abnormalities to the pathogenesis of arthritis has not yet been determined; the role of T cells is especially unclear since synovial hypertrophy and joint erosions have been noted in some studies in the absence of a significant T cell infiltrate. Therefore, to determine if T cells are required for arthritis in MRL-lpr/lpr mice, we evaluated the effects of prolonged treatment with a monoclonal anti-CD4 antibody. Knee joints from treated mice had markedly reduced arthritis compared to saline-treated control animals as measured by the degree of synovial hypertrophy and inflammation. Nephritis in these mice was concomitantly reduced. In contrast, rheumatoid factor levels were not affected by CD4+ cell depletion, despite significant effects on anti-DNA. These results indicate that in MRL-lpr/lpr mice anti-CD4 therapy can inhibit arthritis, suggesting an important role of T cells in the pathogenesis of this lesion.

Animals↗
PubMed1992

A defect in the humoral immune response to protein antigens and haptens in immunoglobulin mu heavy-chain transgenic mice.

We have examined the antibody response in mice expressing a functionally rearranged mu Ig heavy chain derived from a hybridoma antibody with specificity for the hapten 4-hydroxy-3-nitrophenyl (NP). Transgenic mice and their normal littermates were immunized with the antigens NP-OVA, the synthetic polypeptide (Tyr,Glu)-Ala-Lys ((T,G)-A-L), or saline. The presence of serum antibodies to NP-BSA, OVA, (T,G)-A-L, and BSA was examined by ELISA. Sera were evaluated prior to immunization and at periods of up to 4 months following immunization. Prior to immunization, transgenic mice had high levels of IgM anti-NP antibody but no detectable antibody to the other antigens. Both the primary and secondary antibody responses of transgenic mice to NP, OVA, and (T,G)-A-L were depressed when compared with the response of non-transgenic mice. Because of reports that these transgenic mice have increased proportions of CD5 + B-cells, a subpopulation associated with the production of autoantibodies, we examined these mice for the production of both IgG and IgM rheumatoid factors and anti-DNA antibodies. Transgenic mice had a modest increase in the spontaneous production of IgM anti-DNA. These data demonstrate a functional defect in the humoral immune response of mu transgenic mice.

Animals↗
PubMed1992

Thromboxane receptor blockade reduces renal injury in murine lupus nephritis.

To investigate the role of thromboxane A2 (TxA2) in murine lupus, we assessed the effects of the specific thromboxane receptor antagonist GR32191 on immune complex glomerulonephritis in MRL-lpr/lpr mice. Forty mg/kg/day GR32191 was given by twice daily subcutaneous injection for eight weeks beginning at 12 weeks of age. This dose completely blocked the renal vasoconstriction produced by the thromboxane agonist U46619. After eight weeks of treatment, both glomerular filtration rate (GFR) (8.9 +/- 0.6 vs. 6.8 +/- 1.1 ml/min/kg; P less than 0.05) and PAH clearance (CPAH) (37.4 +/- 2.5 vs. 29.9 +/- 3.3 ml/min/kg; P less than 0.05) were significantly higher in mice given GR32191 compared to vehicle treated animals. Administration of GR32191 also reduced proteinuria from 18.1 +/- 11.6 to 3.7 +/- 1.3 mg/24 hours (P less than 0.05). In GR32191 treated MRL-lpr/lpr mice, renal hemodynamic function and proteinuria were not significantly different from congenic MRL-+/+ controls. Thromboxane receptor blockade had striking affects on renal histomorphology reducing both hyaline thrombi in glomeruli (P = 0.022) and interstitial inflammation (P = 0.006). Glomerular crescents and severity of vasculitis also tended to be reduced in mice receiving the thromboxane receptor antagonist. The overall histopathologic score in mice given GR32191 was significantly lower than vehicle treated animals (4.7 +/- 0.5 vs. 8.4 +/- 1.5; P = 0.016). These effects of GR32191 were associated with decreased excretion of thromboxane B2 (TxB2) in urine (292 +/- 37 vs. 747 +/- 155 pg/24 hr; P less than 0.005) as well as a modest reduction in glomerular deposits of IgG (semiquantitative score 2.6 +/- 0.2 vs. 3.5 +/- 0.2; P less than 0.02). Thus, chronic thromboxane receptor blockade markedly altered the course of renal disease in MRL-lpr/lpr mice, suggesting that TxA2 is an important mediator of renal dysfunction and injury in this murine model of lupus nephritis.

Animals↗
PubMed1992

Immunochemical properties of anti-DNA antibodies in the sera of patients with Escherichia coli bacteremia.

To assess the role of infection in anti-DNA antibody production, the DNA-binding activity of sera from patients with Escherichia coli bacteremia was analyzed. Among 8 patients with bacteremia documented by blood culture, 5 demonstrated increased levels of antibodies to single-stranded DNA from E. coli as measured by enzyme-linked immunosorbent assay. Sera from these patients also reacted with single-stranded DNA from other bacterial and mammalian species as well as certain synthetic polynucleotides including poly-dT and poly-dC. The isotype distribution of these antibodies and their avidity as assessed by competition enzyme-linked immunosorbent assay resembled, moreover, responses of patients with systemic lupus erythematosus. These results suggest that, during the course of infection with E. coli, some patients may produce antibodies with immunochemical properties similar to those arising in systemic lupus erythematosus.

Aged↗
PubMed1992

Autoantibodies and their idiotypes.

Antinuclear antibodies occur prominently in systemic lupus erythematosus and serve as markers of underlying pathogenetic disturbances. Although these antibodies display features indicative of genetic control and in vivo selection by self-antigen, other mechanisms shaping the B-cell repertoire may influence their production. Provocative new animal models provide systems for analyzing the cellular and genetic disturbances promoting these responses, as well as the role of pathogenic specificities in inducing tissue injury.

Animals↗
PubMed1992

Anti-DNA antibodies in systemic lupus erythematosus.

Anti-DNA antibodies are the serologic hallmark of systemic lupus erythematosus and important markers for diagnosis and prognosis. Although a number of mechanisms for anti-DNA production have been proposed, recent evidence from human as well as murine lupus indicate a prominent role of DNA antigen drive. To identify further the basis of this response, current research is focusing on the structural features of DNA associated with immunogenicity in both the normal and autoimmune settings. Elucidating these mechanisms should thus provide insights into the pathogenesis of systemic lupus erythematosus as well as the immunologic activity of nucleic acids.

Antibodies, Antinuclear↗
PubMed1991

Stimulation of in vitro murine lymphocyte proliferation by bacterial DNA.

Although DNA is generally considered to be a poor immunogen, recent evidence suggests that DNA from various species differ in their immunologic activity and that bacterial DNA, unlike mammalian DNA, can induce significant antibody responses in mice. To explore further the immunologic activities of bacterial DNA, its ability to stimulate in vitro proliferation of murine lymphocytes was tested. The stimulation of lymphocytes with highly purified ssDNA from Escherichia coli resulted in a dose-dependent response that was maximal at 48 h. Several lines of evidence indicate that DNA, rather than endotoxin contamination, induced this response: 1) LPS at doses equivalent to those detected in the DNA preparation caused significantly less proliferation than the DNA; 2) the response to DNA was insensitive to polymyxin B; 3) pretreatment of DNA with DNase completely abrogated the response; and 4) DNA induced the proliferation of cells from endotoxin-resistant C3H/HeJ mice. Furthermore, although DNA from three different bacterial species induced proliferation, mammalian DNA from three species were nonmitogenic. Depletion of T cells from lymphocytes did not reduce proliferation, suggesting that bacterial DNA directly triggered B cell proliferation. These studies provide further evidence that DNA are not uniform in their immunologic activities likely because of their content of nonconserved structural determinants.

Animals↗
PubMed1991

Anti-La antibody production by MRL-1pr/1pr mice. Analysis of fine specificity.

In evaluating the origin of autoantibodies, patterns of self-Ag recognition have been interpreted to reflect the relative role of Ag in stimulating a response. Few studies, however, have assessed whether human autoantibodies display patterns of autoantigen recognition similar to those of SLE-prone mice. In previous studies, anti-La antibodies from humans have been shown to bind multiple epitopes on recombinant human La Ag, including immunoreactivity with a large fragment, termed La C, representing the middle portion of the La sequence. We report herein for the first time that MRL-1pr mice also spontaneously produce antibodies to recombinant human La protein and resemble human autoantibodies in their reactivity with La C. To further investigate the fine specificity of this response, we tested for antibody binding to six synthetic La peptides representing sequences within La C. Whereas two of the synthetic La peptides reacted with MRL-1pr sera containing anti-La binding, low reactivity was observed with a large panel of human anti-La sera. Our results therefore show that patterns of La antigen recognition displayed by MRL-1pr antibodies differ from those of human autoantibodies, possibly reflecting differences between mouse and man in the induction of these responses.

Animals↗