Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024141 (systemic lupus erythematosus)
 44,322 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A sensitivie and simple procedure for the detection and quantitation of soluble complement (C)- fixing immune complexes in sera of patients with various disease states has been developed by utilizing C receptors on Raji cells. These cells lack membrane-bound immunoglobulin but have receptors for IgG Fc, C3b, C3d, and possibly with other C proteins. Uptake experiments showed that both aggregated human gamma globulin (AHG) and 7S IgG bound to receptors for IgG Fc; however, AHG reacted with C bound to cells only via receptors for C and this binding was much more efficient than via IgG Fc receptors. AHG was used as an in vitro model of human immune complexes and its uptake by Raji cells was quantitated by 125I-radiolabeled antihuman IgG. The limit of sensitivity of this test was 6 mug AHG/ml serum. The ability of Raji cells to detect AHG in serum depended on the amount of radioactive antibody used and the size of aggregates. The presence of an excess of C somewhat inhibited binding of AHG containing C to Raji cells. The efficient binding of AHG by receptors for C on Raji cells was used for the detection and quantitation of immune complexes in human sera. Raji cells were incubated with sera to be tested and then reacted with excess radiolabeled antihuman IgG; the amount of radioactivity bound to the washed cells was determined and referred to a standard curve of radioactive antibody uptake by cells previously incubated with increasing amounts of AHG in serum. Thereby immune complexes were detected and quantitated in serum hepatitis, systemic lupus erythematosus, vasculitis, subacute sclerosing panencephalitis, dengue hemorrhagic fever, and malignancies.
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PMID:The Raji cell radioimmune assay for detecting immune complexes in human sera. 12 62

The fixation of complement to the circulating platelet in immune thrombocytopenia was detected by measurement of one of the complement components, C3, on the surface of platelets from patients with idiopathic thrombocytopenic purpura (ITP) and systemic lupus erythematosus (SLE) using the anti-C3 consumption assay. The surface IgG was determined simultaneously using the previously described anti-IgG consumption assay. Washed platelets from normal controls had 3.5 fg (10(-15) g) of C3, or about 11,000 molecules, per platelet, an amount comparable to the IgG (4.1 FG, or 15,000 molecules, per platelet). For most patients with ITP both C3 and IgG were increased on the platelet surface, although for 5 of 16 patients only IgG was increased. Two patients with SLE and thrombocytopenia had an increase in both C3 and Ig, six patients with SLE who were not thrombocytopenic had normal amounts of membrane-bound C3 and IgG. In 5 patients, 3 with ITP and 2 with collagen vascular disease, both surface immunoproteins decreased with successful treatment of the thrombocytopenia.
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PMID:Platelet-bound complement (C3) in immune thrombocytopenia. 56 91

The effect of low-density lipoprotein (LDL) on the binding of DNA and DNA-anti-DNA immune complexes to cultured human skin fibroblasts was examined. Using radioisotope analysis, ELISA and indirect immunofluorescent staining, a correlation between plasma membrane-bound DNA or DNA-anti-DNA immune complexes and cell-associated LDL was established. It was demonstrated that cytotoxicity and internalization of DNA-anti-DNA immune complexes may be LDL mediated. The data obtained suggest that the binding of the major part of DNA and immune complexes bound to surface of normal skin fibroblasts is due to the formation of a DNA-LDL-LDL receptor linkage. A possible role of LDL-containing immune complexes in the pathogenesis of systemic lupus erythematosus is discussed.
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PMID:LDL-mediated interaction of DNA and DNA-anti-DNA immune complexes with cell surface. 200 80

The enhanced HLA class I (Bg) on red blood cells (RBC) of many patients with systemic lupus erythematosus has allowed a significant correlation to be made between their HLA-B types and haemagglutination reactivity with lymphocytotoxic anti-HLA-B sera stimulated by pregnancy alone. Therefore the class I expression on these RBC relates to classical, rather than non-classical, class I gene products. Studies of class I expression on RBC by means of monoclonal antibodies (MAb) to epitopes on the heavy polypeptide chain and beta 2-microglobulin (beta 2m) have suggested that the complete extracellular structure is present. The specific effect of chloroquine in 'stripping HLA' from RBC had been assumed to support the concept that HLA class I was adsorbed from plasma. However, from our data, we conclude that HLA class I is an intrinsic membrane component. We suggest that the action of chloroquine is to remove beta 2m alone, which prevents normal class I expression and also results in conformational changes to the class I heavy chain, but that it is not capable of removing the membrane-bound heavy chain.
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PMID:HLA class I (Bg) antigens on red cells of SLE patients: a serological study with polyclonal and monoclonal antibodies. 276 4

The interaction of the mouse hepatitis virus (MHV) nucleocapsid protein (N) and viral RNA was examined. Monoclonal antibody specific for N protein coimmunoprecipitated MHV genomic RNA as well as all six MHV subgenomic mRNAs found in MHV-infected cells. In contrast, monoclonal antibodies to the MHV E2 or E1 envelope glycoproteins, an anti-I-A monoclonal antibody, and serum samples from lupus patients did not immunoprecipitate the MHV mRNAs. Moreover, the anti-N monoclonal antibody did not coimmunoprecipitate vesicular stomatitis virus RNA or host cell RNA under conditions which immunoprecipitated all MHV RNAs. These data suggest a specific interaction between the N protein and the virus-specific mRNAs. Both the membrane-bound and cytosolic small MHV leader-specific RNAs of greater than 65 nucleotides long were immunoprecipitated only by anti-N monoclonal antibody. These data suggest that an N binding site is present within the leader RNA sequences at a site at least 65 nucleotides from the 5' end of genomic RNA and all six subgenomic mRNAs. The larger leader-containing RNAs originating from mRNA 1 and mRNA 6, as well as the MHV negative-stranded RNA, were also immunoprecipitated by the anti-N monoclonal antibody. These data indicate that the MHV N protein is associated with MHV-specific RNAs and RNA intermediates and may play an important functional role during MHV transcription and replication.
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PMID:Interactions between coronavirus nucleocapsid protein and viral RNAs: implications for viral transcription. 284 40

The 4-aminoquinolines chloroquine (CQ) and hydroxychloroquine (HCQ), and previously the 9-aminoacridine mepacrine (quinacrine) (MP), have been widely used in the treatment of inflammatory disorders such as rheumatoid arthritis and systemic lupus erythematosus. Their effects are believed to be mediated through phagocytic cells but the precise biochemical basis remains uncertain. We have investigated the effects of these drugs on monocyte superoxide anion (SO) generation elicited by 5 different stimuli-opsonised zymosan (STZ), FMLP, A23187, TPA and fluoride--and sought correlations with effects on two processes which have been linked with monocyte activation, namely arachidonate (AA) release and transmethylation of phosphatidyl ethanolamine (PE) to phosphatidylcholine (PC). In all experiments conditions were adjusted to achieve leucocyte concentrations of drug comparable to those found during in vivo therapy. Neither CQ nor HCQ had any marked effect on SO release induced by TPA, A23187 or fluoride ion, excluding a significant effect on protein kinase C (PKC), calmodulin-dependent kinase(s) or the membrane-bound, superoxide generating NADP(H) oxidase. In contrast MP inhibited the response to TPA and A23187. Each drug also had different effects on surface receptor-dependent responses; thus HCQ inhibited FMLP- but not STZ-induced SO release, whereas CQ and MP inhibited the response to both stimuli. Each drug also displayed different effects on AA release and phospholipid (PL)-methylation; MP and HCQ, but not CQ, inhibited STZ-stimulated AA release while MP and CQ but not HCQ inhibited basal rates of PL-methylation in mononuclear cells (MNC). However, only MP inhibited PL-methylation in an enriched monocyte population. We conclude that despite their close structural similarity, MP, CQ and HCQ each have different metabolic effects and their actions cannot simply be attributed to inhibition of lysosomal functions. Other possible mechanisms of action are discussed. The selective effects of each drug also provide further evidence for multiple pathways of monocyte activation.
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PMID:Differential effects of mepacrine, chloroquine and hydroxychloroquine on superoxide anion generation, phospholipid methylation and arachidonic acid release by human blood monocytes. 301 54

Acquired abnormalities of platelet aggregation have been reported with increasing frequency. We studied five patients (including two with systemic lupus erythematosus and one with compensated chronic idiopathic thrombocytopenic purpura) in whom platelet aggregation responses to collagen, epinephrine and ADP are impaired; in all cases, we found that levels of platelet-associated immunoglobulin G (IgG) were increased. In all five patients substances stored in platelet-dense granules (ATP, ADP, serotonin and calcium) were diminished. The content of the alpha-granule substance, beta-thromboglobulin, was also decreased in most cases, whereas the levels of two secretable acid hydrolase enzymes (beta-glucuronidase and beta-N-acetyl glucosaminidase) were within normal limits. These findings are similar to those observed in subtypes of congenital storage pool deficiency. However, in contrast to the congenital disorder, a membrane-bound (nonsecretable) acid phosphatase was also decreased in the patients with acquired storage pool deficiency. These findings suggest that impaired platelet aggregation on an acquired basis may, in some patients, be due to immune platelet damage resulting in a distinctive type of platelet storage pool deficiency.
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PMID:Acquired storage pool deficiency with increased platelet-associated IgG. Report of five cases. 644 50

Intercellular adhesion molecule-1 (ICAM-1) is a membrane-bound molecule that is primarily involved in cell-cell adhesive interactions of the immune system. The levels of soluble ICAM-1 (s-ICAM-1) shed into the circulation were studied in the sera of patients with systemic lupus erythematosus (SLE) by an enzyme linked immunosorbent assay. Serum concentrations of s-ICAM-1 were significantly increased in 61 patients with SLE compared to 51 controls (mean +/- SEM: 564 +/- 30 versus 348 +/- 17 ng/ml, p < 0.0001) and 41% of patients had higher serum levels than the normal cut off value of 584 ng/ml. Among the various clinical manifestations, skin involvement was significantly associated with high serum levels of s-ICAM-1. Individual values of serum s-ICAM-1 concentrations in patients with SLE correlated significantly with two different disease activity indices, as well as with the erythrocyte sedimentation rate and serum levels of soluble interleukin-2 receptors, but not with serum levels of anti-dsDNA antibodies or C4. No significant differences in s-ICAM-1 levels were found between patients receiving immunomodulatory treatment and those who were not. These findings suggest that s-ICAM-1 measurement may serve as an additional serologic marker of disease activity in patients with SLE. Further studies to determine whether increased s-ICAM-1 shedding has any pathogenetic significance or biological role in SLE are warranted.
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PMID:Increased levels of intercellular adhesion molecule-1 in the serum of patients with systemic lupus erythematosus. 790 80

Mice homozygous for the lymphoproliferation (lpr) mutation, which disrupts expression of the Fas cell surface molecule, develop an autoimmune syndrome with a spectrum of autoantibodies resembling human SLE. It is not known how the loss of Fas leads to autoantibody production. To study the fate of autoreactive B cells in lpr/lpr mice, C57BL/6 (B6) strain transgenic mice expressing hen egg lysozyme (HEL) as a model autoantigen in soluble or membrane-bound forms and carrying HEL-specific Ig (Ig) transgenes were mated onto the congenic B6-lpr/lpr background. Despite the absence of Fas, elimination of self-reactive lpr/lpr B cells recognizing membrane-bound autoantigen occurred as efficiently as in autoreactive B cells bearing the wild-type (+/+) Fas gene. Functional inactivation of autoreactive B cells binding soluble HEL also occurred normally in most young lpr/lpr animals. Nevertheless, breakdown of B cell tolerance to soluble lysozyme occurred in one of eight young lpr/lpr animals and in four of seven old animals with lymphadenopathy. Interestingly, the presence of the rearranged Ig transgenes markedly delayed the onset of lymphadenopathy. These results demonstrate that Fas is not an essential molecule in the biochemical pathways mediating autoreactive B cell elimination or inactivation. The breakdown of tolerance observed in a considerable fraction of older animals nevertheless confirms that autoantibody production in this model of SLE involves a defect in active censoring of autoreactive B cells. The possible basis for that defect is discussed.
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PMID:Effects of the lpr mutation on elimination and inactivation of self-reactive B cells. 807 85

Complement receptor 1 (CR1) is present on erythrocytes (E-CR1), various leucocytes, and renal glomerular epithelial cells (podocytes). In addition, plasma contains a soluble form of CR1 (sCR1). By using a specific ELISA, CR1 was detected in the urine (uCR1) of normal individuals (excretion rate in 12 subjects, 3.12 +/- 1.15 micrograms/24 h). Contrary to sCR1, uCR1 was pelleted by centrifugation at 200,000 g for 60 min. Analysis by sucrose density gradient ultracentrifugation showed that uCR1 was sedimenting in fractions larger than 19 S, whereas sCR1 was found as expected in fractions smaller than 19 S. The addition of detergents reduced the apparent size of uCR1 to that of sCR1. After gel filtration on Sephacryl-300 of normal urine, the fractions containing uCR1 were found to be enriched in cholesterol and phospholipids. The membrane-association of uCR1 was demonstrated by analyzing immunoaffinity purified uCR1 by electron microscopy which revealed membrane-bound vesicles. The apparent molecular mass of uCR1 was 15 kD larger than E-CR1 and sCR1 when assessed by SDS-PAGE and immunoblotting. This difference in size could not be explained on the basis of glycosylation only, since pretreatment with N-glycosidase F reduced the size of all forms of CR1; however, the difference in regular molecular mass was not abrogated. The structural alleles described for E-CR1 were also found for uCR1. The urine of patients who had undergone renal transplantation contained alleles of uCR1 which were discordant with E-CR1 in 7 of 11 individuals, indicating that uCR1 originated from the kidney. uCR1 was shown to bind C3b-coated immune complexes, suggesting that the function of CR1 was not destroyed in urine. A decrease in uCR1 excretion was observed in 3 of 10 patients with systemic lupus erythematosus, corresponding to the three who had severe proliferative nephritis, and in three of three patients with focal sclerosis, but not in six other patients with proteinuria. Taken together, these data suggest that glomerular podocytes release CR1-coated vesicles into the urine. The function of this release remains to be defined, but it may be used as a marker for podocyte injury.
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PMID:Identification of membrane-bound CR1 (CD35) in human urine: evidence for its release by glomerular podocytes. 811 81


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