Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The purpose of the present investigation was to examine the production of specific salivary antibodies after oral immunization of axenic mice (ICR/CD-1) with formalinized Escherichia coli (ATCC 11775). Three aspects of the humoral response were studied: (i) the sequential appearance of anti-E. coli antibodies; (ii) classes of antibodies produced in response to the antigen; and (iii) antibody specificity. Antibody levels were determined by passive hemagglutination with soluble lipoplysaccharide and bacterial agglutination, using preparations of somatic O and flagellar H antigens. A short latent period of 1 to 3 days was observed when saliva samples were assayed for anti-lipopolysaccharide and anti-O antibodies. The salivary antibody titers peaked at 11 days after initiation of the immunization regimen. Only two of six mice exhibited a change in serum antibody levels against these antigens. The predominant class of early antibody in saliva was immunoglobulin (Ig)G; however by 7 days IgA WAS found to comprise the major portion of specific immunoglobulins. Serum antibodies directed against falgellar antigenic determinants were primarily of the IgM class, whereas the salivary antibodies were IgG in nature.
 ...
PMID:Sequential appearance of salivary antibodies after oral immunization of axenic mice. 109 5

Mouse spleen cells, cultured on surfaces coated with antigen-antibody complexes, are inhibited from responding to the B-cell mitogens, lipopolysaccharide, lipid A, Pneumococcal polysaccharide SIII, and poly I:C. The response to the T-cell mitogen, concanavalin A, is also substantially inhibited by immobilized antigen-antibody complexes, but specific inhibition of the response to phytohemagglutinin is minimal. Control experiments showed that immobilized complexes prepared from IgG F(ab')2 fragments and IgA antibodies (both of which fail to bind to Fc receptors when complexed to antigen) did not show significant inhibitory activity when compared with the inhibition observed with complexes prepared from whole IgG. Suspensions of antigen-antibody complexes prepared from the same antigen and intact IgG antibody did not inhibit mitogenesis. None of the mitogens used could be demonstrated to compete with the binding of aggregated immunoglobulin to the B-cell Fc receptor. It appears that the interaction of Fc receptor-bearing lymphocytes and/or macrophages with immobilized complexes prevents lymphocyte activation by mitogens. It is suggested that the mechanism(s) involved may be relevant to antibody feedback control of the humoral immune response.
 ...
PMID:Inhibition of lymphocyte mitogenesis by immobilized antigen-antibody complexes. 118 5

Outer membrane proteins (OMP) of Porphyromonas endodontalis HG 370 (ATCC 35406) were prepared from the cell envelope fraction of the organisms. The cell envelope that had been obtained by sonication of the whole cells was extracted in 2% lithium dodecyl sulfate and then successively chromatographed with Sephacryl S-200 HR and DEAE-Sepharose Fast Flow. Two OMP fractions, OMP-I and OMP-II, were obtained, and their immunochemical properties and induction of specific antibodies were examined. The OMP-I preparation consisted of a major protein with an apparent molecular mass of 31 kDa and other moderate to minor proteins of 40.3, 51.4, 67, and 71.6 kDa, while the OMP-II preparation contained 14-, 15.5-, 27-, and 44-kDa proteins as revealed by sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis. OMP-I was found to form hydrophilic diffusion pores by incorporation into artificial liposomes composed of egg yolk phosphatidylcholine and dicetylphosphate, indicating that OMP-I exhibited significant porin activity. However, the liposomes containing heat-denatured OMP-I were scarcely active. Spontaneous and antigen-specific immunoglobulin M (IgM)-, IgG-, and IgA-secreting spot-forming cells (SFC) enzymatically dissociated into single-cell suspensions from chronically inflamed periapical tissues and were enumerated by enzyme-linked immunospot assay. In patients with radicular cysts or dental granulomas, the major isotype of spontaneous SFC was IgG. In radicular cysts, the OMP-II-specific IgG SFC represented 0.13% of the total IgG SFC, while the antigen-specific IgA or IgM SFC was not observed. It was also found that none of these mononuclear cells produced antibodies specific for OMP-I or lipopolysaccharide of P. endodontalis.
 ...
PMID:Immunochemical and biological characterization of outer membrane proteins of Porphyromonas endodontalis. 132 59

Lymphokine directed isotype switching is preceded by the induced expression of the corresponding germline Ig heavy chain constant region (CH) gene. This association favors a model in which lymphokine induced germline CH gene expression promotes switch recombination by increasing the accessibility of the switch region to a recombinase(s). An important prediction of this model is that the induction of germline CH RNAs represents increased specific de novo transcription. To test if this prediction is fulfilled by the switch commitment factors, IL-4 and transforming growth factor-beta (TGF-beta), we have utilized a B cell line, 1.29, that switches from IgM to IgE and IgA in vitro. In this cell line, IL-4 and TGF-beta increase germline C epsilon and C alpha RNA levels respectively, predominantly by elevating transcription of these genes. Transcription of germline C epsilon and C alpha genes appears to be independently regulated and is not affected by lipopolysaccharide or IL-5. These results are discussed in the context of the molecular events necessary to commit a B cell to an isotype switch.
 ...
PMID:Transcriptional regulation of the germline immunoglobulin C alpha and C epsilon genes: implications for commitment to an isotype switch. 136 52

Various surface structures can be expressed in Bacteroides fragilis, but little is known about capsular structures in other non-spore-forming anaerobes. Fimbriae have been isolated from Bacteroides fragilis and Porphyromonas gingivalis. The importance of iron-repressible outer membrane proteins as virulence factors in Bacteroides fragilis is under study. The low endotoxic activity of Bacteroides fragilis lipopolysaccharide can be attributed to the chemical composition of this organism's lipid A. A tissue culture system for the demonstration of Bacteroides fragilis enterotoxin has recently been described. The toxins A and B of Clostridium difficile are immunologically distinct. The importance of IgA proteases and other enzymes as virulence factors in anaerobic bacteria remains unclear.
 ...
PMID:Virulence factors in anaerobic bacteria. 136 45

T cell-dependent B cell activation and the induction of isotype switching require antigen and direct contact with helper T (Th) cells. During activation, B cells can switch from the expression of IgM to that of IgG, IgE or IgA, depending on the lymphokines secreted by the Th cell with which they interact. Studies of lipopolysaccharide (LPS)-activated B cells have suggested that lymphokines regulate isotype switching via a transcriptional mechanism that increases the accessibility of downstream CH genes to a switch recombinase(s). To assess the roles of T cell contact and lymphokines in isotype switching, we have examined the accessibility model for the regulation of isotype switching to IgG1 in the context of cognate interactions between Th cells and normal B cells. We demonstrate that Th2 cells that secrete IL-4 can induce expression of germline gamma 1 transcripts in B cells. The steady-state level of germline gamma 1 transcripts induced by Th2 cells is enhanced as compared with the level induced by IL-4 alone or Il-4 and LPS also alters the relative usage of the germline gamma 1 transcription initiation sites. Enhanced expression of germline gamma 1 transcripts requires direct contact between T and B cells suggesting a role for T cell contact-mediated signals in regulating the accessibility of switch regions.
 ...
PMID:IL-4-induced expression of germline gamma 1 transcripts in B cells following cognate interactions with T helper cells. 137 44

Enzyme-linked immunosorbent assays were developed separately for the three main parts of the Pseudomonas aeruginosa lipopolysaccharide (LPS) molecule, namely, lipid A, core, and O polysaccharide. Anti-lipid A, anticore, and anti-O polysaccharide antibodies were measured in serum samples from 12 patients with cystic fibrosis (CF) in a longitudinal study covering the period before P. aeruginosa infection was established through at least 5 years of chronic infection. The serum antibody response to all parts of the P. aeruginosa LPS molecule increased during the course of chronic infection. The increase in anti-lipid A antibodies was specific for P. aeruginosa lipid A, since no increase in anti-Escherichia coli lipid A antibodies was seen. Immunoglobulin G, A, and M (IgG, IgA and IgM) antibodies were all involved in the specific systemic response to P. aeruginosa lipid A, core, and the O polysaccharides. IgG and IgA levels in particular increased during the course of infection and were significantly higher than the antibody increase seen with age in a healthy control group. The local immune response in the lungs was investigated by measuring IgG, IgA, and IgM antibodies to the separate parts of the P. aeruginosa LPS molecule in sputum samples from 18 CF patients with at least a 5-year history of chronic P. aeruginosa infection. Antibodies detected in sputum were mainly anti-lipid A and anti-O polysaccharide antibodies of the IgG and IgA isotypes. Very high IgA anti-lipid A titers were detected in sputum samples from some CF patients.
 ...
PMID:Antibody responses to lipid A, core, and O sugars of the Pseudomonas aeruginosa lipopolysaccharide in chronically infected cystic fibrosis patients. 137 55

Antibody responses to ingested antigens can be inhibited by a mechanism known as oral tolerance which acts to prevent excessive stimulation from luminal contents. Local IgA responses can be induced in this non-responsive environment and during intestinal inflammation, mucosal IgG responses can also be increased. The purpose of this study was to compare a panel of cytokines to factors from macrophage-T cell co-culture supernatants for their ability to enhance isotype and sheep red blood cell (SRBC)-specific plaque-forming cell responses in an in vitro model of oral tolerance. IL-2, IL-4, IL-5, and IL-6, which have been implicated in IgA regulation of lipopolysaccharide-stimulated B cells, were not capable of enhancing responses in tolerized cultures; however, transforming growth factor (TGF)-beta 1 had a dose-dependent ability to enhance responses to the T cell-dependent antigen SRBCs in this system. The enhancement was only seen when antigen was present and was neutralized by specific rabbit antiserum but not normal rabbit IgG. Similar treatment of soluble factors from the macrophage-T cell co-cultures did not inhibit their ability to enhance responses suggesting at least two distinct molecular mechanisms could augment responses in tolerized cultures. This was substantiated further by showing that TGF-beta 1 was not isotype-specific. In contrast, adsorption of the macrophage-T cell co-culture supernatants against monoclonal IgA or IgG removed isotype-specific binding factors which were necessary for the enhancement of IgA and IgG respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Transforming growth factor-beta 1 enhances IgG and IgA sheep red blood cell responses. 139 Apr 40

Patients with alcoholic liver cirrhosis (ALC) have high serum levels and spontaneous in vitro production of immunoglobulin (Ig) A. Deposits of IgA are also found in liver sinusoids. Increased interleukin 6 (IL-6) production is another feature of this disease. This study shows a linear correlation between increased lipopolysaccharide (LPS)-induced IL-6 production and increased spontaneous IgA and IgG secretion by peripheral blood mononuclear cells (PBMCs). PBMCs and purified monocytes isolated from healthy control subjects and patients with ALC contain elevated IL-6 messenger RNA levels and produce IL-6 in response to stimulation with soluble polymeric IgA (p-IgA) or attached monomeric IgA (m-IgA) but not with soluble m-IgA. The addition of monospecific antibody to human IL-6 inhibits spontaneous IgA production by PBMC. This inhibition is more pronounced in patients with ALC. These data provide evidence that IgA, possibly by attachment to cells possessing Fc alpha receptors and secreting IL-6, is involved in the production of this major mediator and the amplification of Ig secretion. Circulating IgA and IgA deposits could therefore initiate a process of autoamplification implicated in the development of hypergammaglobulinemia in ALC.
 ...
PMID:Immunoglobulin A and interleukin 6 form a positive secretory feedback loop: a study of normal subjects and alcoholic cirrhotics. 139 88

Selective IgM deficiency was diagnosed in a 3-month-old Standardbred colt that was referred for chronic respiratory tract disease. Immunoglobulin quantification revealed normal IgG and IgA concentrations, but undetectable IgM concentration. Stimulation of blood lymphocytes with the T-cell mitogens concanavalin A and phytohemagglutinin yielded results within the normal range. However, stimulation with the B-cell mitogen lipopolysaccharide produced no response. A B-cell defect similar to that associated with several immunodeficiency disorders in people was suggested as the cause of the IgM deficiency in this colt.
 ...
PMID:Selective IgM deficiency and abnormal B-cell response in a foal. 142 87


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>