Serum antibody to retroviral gag proteins in systemic sclerosis.
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Antibodies↗
Biomedical subjects
H Dang
Publications and source records attributed to H Dang.
Percutaneous removal of transvenous pacing lead perforating the heart, pericardium, and pleura.
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Adult↗
Structural and functional analyses of a yeast mitochondrial ribosomal protein homologous to ribosomal protein S15 of Escherichia coli.
We have purified a small subunit mitochondrial ribosomal protein, MRPS28p, from the yeast, Saccharomyces cerevisiae. Sequence from the amino terminus of MRPS28p was used to design a degenerate oligonucleotide that was complementary to the MRPS28 gene. The MRPS28 gene was isolated and its sequence determined. The MRPS28 sequence encodes a 28 kDa protein that has a region of homology with ribosomal protein S15 of E. coli. This region spans the entire length of the E. coli protein, but as MRPS28p is larger, includes only the portion of the MRPS28p sequence from amino acids 150 to 238. Based on this homology, we predict that MRPS28p, like E. coli S15, interacts directly with small subunit rRNA and functions as an early protein in ribosome assembly. Cells carrying a disrupted chromosomal copy of MRPS28 are unable to respire and spontaneously lose portions of their mitochondrial genomes at a high frequency. These phenotypes are consistent with an essential role for MRPS28p in the assembly and/or function of the mitochondrial ribosome.
Amino Acid Sequence↗
Discoordinate expression of the yeast mitochondrial ribosomal protein MRP1.
We have examined expression of the protein coded within the MRP 1 locus of Saccharomyces cerevisiae. Direct evidence is provided for the assignment of the MRP1 gene product as a protein component of the small subunit of mitochondrial ribosomes. Further studies examined the extent to which the expression of the MRP1 protein is coordinated with the expression of other mitochondrial ribosomal components coded in the nuclear and mitochondrial genomes. Extra copies of the MRP1 gene were introduced into yeast cells to perturb expression from MRP1 relative to other mitochondrial ribosomal components to determine whether forms of regulation function to limit the accumulation of either MRP1 mRNA or protein under these conditions. Increases in MRP1 gene dosage were accompanied by substantial increases in both MRP1 mRNA and protein, indicating that their accumulation was not linked to the level of expression of other mitochondrial ribosomal components. This conclusion was confirmed by additional studies that showed that the accumulation of the MRP1 protein was unaffected in cells that did not express mitochondrially-encoded rRNAs. These results contrast with previous studies on the expression of two other mitochondrial ribosomal proteins indicating that regulatory properties of mitochondrial ribosomal proteins are quite diverse.
Genes, Fungal↗
Anti-peptide antibodies detect a lupus-related interspecies idiotype that maps to H chain CDR2.
Antibodies to the small nucleoprotein Sm occur spontaneously in human and murine systemic lupus erythematosus. Human and mouse monoclonal anti-Sm autoantibodies designated 4B4 and Y2 share an idiotype (Id) determinant located on the Ig H chain. To understand the molecular basis of this cross-reactivity, the VH regions of both antibodies were sequenced and analyzed for homology. The antibodies showed only 49.6% homology. The second complementary determining region (CDR2) was the most likely candidate for the Id site. To investigate this possibility, rabbit antiserum was made against a peptide corresponding to the CDR2 of 4B4. This antiserum was specific for the immunizing peptide and reacted weakly to a peptide corresponding to the CDR2 of Y2. Anti-CDR2 antibody bound to 4B4 and Y2 but not to other human and mouse mAb. Binding was directed at the H chain when analyzed by Western blots. Anti-CDR2 antibody blocked anti-Id antibody binding to 4B4 and Y2 by 58% and 24%, respectively. These studies suggest that this interspecies Id maps to the H chain CDR2 and that a conserved Id can occur within molecules that are otherwise radically different.
Amino Acid Sequence↗
Detection of serum antibodies to retroviral proteins in patients with primary Sjögren's syndrome (autoimmune exocrinopathy).
Primary Sjögren's syndrome (SS) is considered a benign autoimmune disease; it is characterized by lymphoid infiltration of salivary and lacrimal glands, often accompanied by the presence of serum autoantibodies, particularly anti-Ro (SS-A) and anti-La (SS-B). There are important immunologic similarities between primary SS and acquired immunodeficiency syndrome. To investigate for a possible immune response to retroviral proteins in primary SS, we performed immunoblotting against human immunodeficiency virus-1 (HIV-1) proteins using sera from 47 patients with primary SS. Moderate-to-strong reactivity, suggesting the presence of serum antibodies, was found in 14 patients (30%). Of 120 normal subjects, only 1 showed moderate positivity. All 14 positive SS sera reacted against p24 (gag) but failed to react against gp41 or gp120 (env). This response did not reflect hypergammaglobulinemia since immunoglobulin concentrations among the 29 SS patients studied were the same in sera that contained and sera that did not contain anti-gag reactivity. Two sera also reacted against p17 gag. Four reacted against HIV-2 core proteins, but none reacted with core proteins of human T lymphotropic virus-I. Only 1 of the 14 sera reacted against Ro (SS-A), and 1 other reacted against La (SS-B). These results identify a subset of SS patients characterized by 1) the presence of serum antibodies to HIV-1 group-specific, but not type-specific, proteins, and 2) the relative absence of anti-Ro (SS-A) and anti-La (SS-B) autoantibodies. In this latter respect, these SS patients constitute a subpopulation that resembles patients with HIV-induced SS-like disease.
Adult↗
Accelerated expression of anti-Sm and Y2 idiotype differ in dependence on T cell subsets in MRL/+ mice.
We investigated the role of MRl T cells in the induction of anti-Sm antibodies and Y2 idiotype. Four injections of Sm antigen in Freund's complete adjuvant were required to induce peak amounts of specific anti-Sm antibody in young BALB/c and MRL/+ mice. The Y2 idiotype was expressed in MRL/+ mice but not in BALB/c mice. Expression of both anti-Sm, predominantly IgG2a heavy chain, and Y2 idiotype was augmented in MRL/+ mice after two injections of Sm if, prior to immunization, mice received splenic T cells from naive MRL/lpr or immunized, but not naive MRL/+ mice. These results suggest that the lpr gene contributes to the ability of autoimmune T cells to augment the anti-Sm antibody response. Treatment of primed MRL/+ donor T cells with anti-CD4, but not anti-CD8, antibodies and complement removed the ability to augment anti-Sm antibody production. In contrast, augmentation of Y2 idiotype production was abrogated by pretreatment of donor T cells with either anti-CD4 or anti-CD8. These results suggest that, while MRL/+ CD4+ T cells play an important role in anti-Sm antibody production, additional interaction between CD4+ and CD8+ T cells augments Y2 expression.
Animals↗
A conserved idiotype and antibodies to retroviral proteins in systemic lupus erythematosus.
22 of 61 systemic lupus erythematosus (SLE) patients produced antibodies to the p24 gag protein of HIV-1 demonstrated by Western blotting. 20 of these 22 patients (91%) also express the 4B4 idiotype (Id 4B4) previously identified on a human anti-Sm monoclonal antibody called 4B4. This represents an enrichment for this Id (seen in only 52% of SLE patients generally). Eight of these 22 SLE patients also have anti-Sm antibody activity. Sm partially inhibits the antibody binding of p24 gag suggesting immunologic cross-reactivity between the retroviral antigen p24 gag and the autoantigen Sm. Anti-Id 4B4 also inhibits p24 gag antibody binding by as much as 40%. Finally the monoclonal antibody 4B4 showed cross-reactivity to Sm and p24 gag. The following points emerge from our studies: (a) SLE patients make antibodies to p24 gag of HIV-1, (b) there is a relationship between immunity to p24 gag and a conserved idiotype, and (c) anti-Sm antibodies can cross-react with p24 gag.
Autoantigens↗
VH sequence of a human anti-Sm autoantibody. Evidence that autoantibodies can be unmutated copies of germline genes.
The utilization of germline genes for the synthesis of autoantibodies has been suspected for many years based on the presence of cross-reactive idiotypes among patients as well as in some healthy first-degree relatives of patients with several autoimmune diseases including SLE. One such system of idiotypes involves anti-Sm antibodies, which are highly specific for SLE. To definitively establish the utilization of germline genes in the Sm system, we produced human-human B cell hybridomas from a patient with SLE who had circulating anti-Sm antibodies. One stable hybridoma designated 4B4 secretes an IgM-kappa mAb that binds Sm and shares idiotypic determinants with other anti-Sm antibodies. A second anti-Sm antibody (3C3), isolated from the same patient was also studied. Oligo(dT) priming was used to produce cDNA corresponding to full length IgM. Sequence analysis revealed that the VH gene segment (1-96) of 4B4 is identical to a VH sequence previously detected in a fetal liver cDNA library by Schroeder and his co-workers as well as a germline VH recently described by Berman and his associates. The identity of a lupus mAb and sequences derived from unrelated individuals provides strong evidence that this autoantibody is a direct copy of a germline gene.
Amino Acid Sequence↗
Autostimulatory growth factors produced by Sjögren's syndrome B cell lines.
Sjögren's syndrome (SS) is a systemic autoimmune disorder characterized by polyclonal hypergammaglobulinemia, autoantibody formation, and intense tissue infiltration by lymphoid and plasma cells. These patients have a predisposition to the development of monoclonal immunoglobulins and B cell lymphomas. To study the role of B cells in this disease, we established B cell lines from three patients with benign primary SS. These B cell lines grew spontaneously without any stimulation and expressed EBV nuclear antigen. The lines secreted an autostimulatory factor which had properties of a B cell growth factor. Peripheral blood B cells from SS patients, after culture for 3 days, secreted a similar factor which stimulated the proliferation of established SS B cell lines. These results suggest that circulating B cells in SS produce an autocrine growth factor that may contribute to lymphoproliferation and ultimately to the emergence of B cell lymphomas.
B-Lymphocytes↗
Characterization of the IL-2-receptor on rheumatoid arthritis synovial fluid T cells.
We studied the hypoproliferative response of synovial fluid (SF) T cells in rheumatoid arthritis (RA) using a mitogenic monoclonal antibody (MoAb) specific for the T-cell antigen receptor-associated CD3 complex. RASF T cells are defective in their proliferative response and in the induction of the Tac (p55) component of the IL-2-receptor (IL-2-R) when stimulated with anti-CD3 monoclonal antibody (MoAb). However, fresh RASF T cells bear demonstrable IL-2-R in cross-linking experiments which are not seen in unstimulated peripheral blood (PB). These receptors are functional since RASF T cells proliferate in response to recombinant IL-2 (rIL-2) better than fresh PB T cells from either normal or RA patients. Scatchard analysis indicates increased (4-fold) numbers of high affinity IL-2-R on (phytohaemagglutinin) PHA-activated RASF T cells as compared with comparably activated RAPB T cells. Phorbol myristate acetate (PMA) induces Tac antigen expression in RASF but does not lead to proliferation. The hyporesponsiveness of RASF T cells does not appear to result from lack of IL-2-R, lack of IL-2-R inducibility, or proliferative potential.
Adult↗
Autostimulatory factor produced by B-cell lines from patients with Sjögren's syndrome.
Sjögren's syndrome (SS) is an autoimmune disease with a predisposition to transform into a B-cell lymphoma. Stable B-cell lines were established (without exogenous stimulation other than fetal bovine serum) from the peripheral blood of three SS patients. These cell lines secreted immunoglobulin (either IgG, IgM or both) and expressed cytoplasmic immunoglobulin. They were positive for the B-cell markers Leu 12 and Leu 16, and also for HLA-DR and the transferrin receptor. The cells lacked CD3 and the IL-2 receptor. Supernatants from these cell lines had autostimulatory activity. When 24-h culture supernatants were added to freshly cultured peripheral blood mononuclear cells, the proliferation index was 2-3 times higher as compared to cells cultured with HB101 medium alone. This autostimulatory activity can be attributed to a B-cell growth factor since these supernatants were also able (1) to support the growth of BD9 cells and (2) to augment the proliferation of PB B cells preactivated with S. aureus Cowan strain I. Furthermore, the supernatants did not contain IL-1, IL-2, or gamma-interferon. Thus, B cells that grow spontaneously from the peripheral blood of SS patients spontaneously produce a B-cell growth factor. This factor could contribute importantly to the autoantibody production, tissue lymphoid infiltration and B-cell lymphoma seen in this disease.
B-Lymphocytes↗
Pupil-sparing oculomotor palsy caused by fusiform arteriosclerotic aneurysm of the basilar artery--a case report.
Paresis of the oculomotor nerve is a very rare complication of an unruptured arteriosclerotic fusiform aneurysm of the basilar artery. A handful of cases are described in the world literature. A fifty-four-year-old man with a history of hypertension and diabetes mellitus presented with painless partial oculomotor palsy of sudden onset. A cerebral angiogram demonstrated a tortuous fusiform deformity of the basilar artery and the origin of the posterior cerebral arteries, indicative of an arteriosclerotic aneurysmal dilation. A sudden onset of a pupil-sparing ophthalmoplegia is the typical history of a microvascular infarct of the third nerve, whereas pupillary sparing in aneurysmal oculomotor paresis is a very rare event. Special emphasis has been placed on the pupillary size as a guide for the indication of arteriography. The many exceptions to this rule suggest that cerebral arteriography may be indicated more often than generally believed.
Basilar Artery↗
Characteristics of a human monoclonal anti-Sm autoantibody expressing an interspecies idiotype.
A human-human hybridoma secreting an anti-Sm mAb designated 4B4 was established by fusion of GM4672 (a lymphoblastoid B cell line) with PWM-activated mononuclear cells from a patient with active SLE. Competitive Ag inhibition assays showed that 4B4 was specific for Sm and did not bind with native or denatured DNA or RNA. Western blot analysis with 4B4 showed that this mAb binds to the B/B' ribonucleoprotein of the Sm/ribonucleo-protein complex. By competitive inhibition assay, 4B4 was demonstrated to partially share idiotypic expression with a mouse anti-Sm mAb designated Y2. This was demonstrated by the ability of each mAb (Y2 or 4B4) to inhibit a homologous anti-idiotypic antibody (either anti-Y2 or anti-4B4) better than the nonhomologous anti-idiotypic antibody. These results confirm previous findings that idiotypes related to Sm-binding are highly conserved in nature. Furthermore, this report is the first idiotypic analysis of a human anti-Sm mAb.
Animals↗
T-cell antigen receptor studies in mice expressing the lpr genetic defect.
Mice having the lpr genetic defect bear an expanding lymphoid T-cell population with unusual cell surface characteristics. Using SDS-PAGE analysis, the T cells from lpr mice were shown to have two forms of the T-cell antigen receptor. A conventional (nonreduced) 90-kDa receptor and a lighter 70- to 85-kDa form were both detected. The 70- to 85-kDa antigen receptor was also shown to be present on lpr thymocytes. Only the normal 90-kDa receptor was found in MRL-++ mice. Treatment of the receptor with N-glycanase shows that the 70- to 85-kD form may be a product of abnormal glycosylation. The low-molecular-weight antigen receptor on lpr T cells is unusual and might contribute in some way to the disordered immunoregulation and autoimmunity that occur spontaneously in these mice.
Animals↗
Contractile responses to adrenergic nerve stimulation are enhanced with removal of endothelium in rat caudal artery.
Removal of the endothelium from isolated perfused rat caudal arteries produced a two fold increase in the contractile response to transmural nerve stimulation. Pretreatment with 6-hydroxydopamine eliminated the contractile response to adrenergic nerve stimulation but failed to uncover any vasodilatory effect of electrical stimulation, either directly on smooth muscle or via non-adrenergic nerves. Endothelial removal also produced two and four fold enhancement of the contractile responses to the selective alpha 1- and alpha 2-adrenoceptor agonists methoxamine and B-HT 920. However, pKB values for prazosin and yohimbine versus both agonists indicate that both methoxamine and B-HT 920 are acting primarily at alpha 1-adrenoceptors in this tissue. These results provide evidence that endothelial factors released either at basal levels or by the stimulation of agonists play a significant physiological role in modifying the contractile responses of blood vessels.
Adrenergic alpha-Agonists↗
Abnormalities of T cell activation in the rheumatoid synovium detected with monoclonal antibodies to CD3.
The chronic inflammation of rheumatoid arthritis (RA) is associated with hypofunction of synovial fluid (SF) T cells. We studied the mechanisms leading to this abnormality using a mitogenic monoclonal antibody specific for the T cell receptor-associated CD3 complex. We found that SF cells are defective in their response to anti-CD3 antibodies as measured by proliferation, generation of natural cytotoxicity, and induction of the Tac (p55) component of the IL2 receptor. Nevertheless, these cells do bear functional IL2 receptors and are more responsive to IL2 than are resting peripheral blood T cells. In searching for a mechanism to explain the reduced IL2 production, we found that polyamines (whose oxidation products can down-regulate proliferation and IL2 production) are elevated in RA cells from both blood and SF. We postulate that the chronic activation of RA T cells triggers this feedback loop which constitutes a defensive mechanism aimed at reducing the T cell driven autoimmune and inflammatory process.
Adult↗
Expression of an interspecies idiotype in sera of SLE patients and their first-degree relatives.
Sera from 29 SLE patients and 81 first-degree healthy family members were tested for quantitative expression of a cross-reactive idiotype present on a murine monoclonal anti-Sm autoantibody (Y2). Forty-one percent of SLE patients and 27% of all relatives showed increased serum levels of the Y2 idiotype compared to 6% in a normal, unrelated control group. In addition, female relatives of SLE patients showed slightly increased levels of anti-Sm antibodies compared to male relatives (15% vs 3%). In one of the 28 families and three unrelated SLE patients studied, there was a significant correlation between the Y2 idiotype expression and expression of another idiotype present on anti-DNA antibodies (1341d). Affinity column absorption studies showed that these two idiotypes were present on different antibody molecules. This study demonstrates: (1) a genetic predisposition for an anti-Sm antibody idiotype expression in humans; and (2) that two different idiotypes may be under parallel or coordinate regulation.
Antibodies, Antinuclear↗