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 immunoglobulin M (IgM) and the IgG1, IgG2ab, and IgG3 subclasses of plaque-forming cells (PFC) specific for lipopolysaccharide (LPS) were measured after immunization of mice with LPS alone and compared with the responses to LPS in combination with nonbacterial proteins and with bacterial membrane phospholipid vesicles or two major outer membrane proteins from Proteus mirabilis. The relative numbers of IgG PFC belonging to the IgG1, IgG2, or IgG3 subclasses induced by immunization with LPS alone depended upon the type of LPS administered. Phospholipids and the proteins effected characteristic alterations in not only the strength but also the subclass of the IgG responses to LPS. The results suggest that the hydrophobic-hydrophilic nature or state of aggregation of the preparations plays a role in the induction of IgG1 and IgG2 subclasses of PFC specific for LPS. Complex formation with LPS and adjuvant was apparently necessary to obtain these effects.
 ...
PMID:Alteration of the immunoglobulin G subclass responses in mice to lipopolysaccharide: effects of nonbacterial proteins and bacterial membrane phospholipids or outer membrane proteins of Proteus mirabilis. 618 89

In the response to NP-lipopolysaccharide or NP-Ficoll predominantly anti-NP antibodies of the IgM class are produced in mice with lower amounts of IgG3 and IgG2b but little or no IgG1 and IgG2a. In contrast, in the primary T-dependent response to NP-keyhole limpet hemocyanin (KLH) or NP-chicken gamma globulin high amounts of all IgG isotypes are induced. To investigate whether isotype-specific T cells are responsible for these differences we carried out cell transfer experiments using carrier-specific T cell lines. Two such lines were established and one of the two could be cloned. Upon activation by antigen the T cell lines induced unprimed syngeneic splenic B cells to proliferate and differentiate into antibody-secreting cells in vitro in an antigen-nonspecific way. Antigen-specific activation of unprimed B cells in a cell transfer system in vivo showed that high concentrations of hapten-specific antibodies of all IgG isotypes are induced through both carrier-specific T helper lines. The isotypic pattern of these antibodies is similar to that produced via heterogeneous splenic T cells in the cell transfer system, or in normal animals on immunization with the same antigen. These results suggest that isotype-specific T cells are not required for the production of IgG isotypes in a primary anti-NP response and thus not responsible for the differences seen in isotypic patterns between T-dependent and T-independent responses.
 ...
PMID:Heterogeneous and monoclonal helper T cells induce similar anti-(4-hydroxy-3-nitrophenyl)acetyl (NP) antibody populations in the primary adoptive response. I. Isotype distribution. 619 16

The ability of antisera against lipopolysaccharide (LPS) raised by immunization with gram-negative bacteria to prevent LPS toxicity and death from gram-negative bacteremia is well established. To demonstrate conclusively that the protective antibody is specific for LPS, we tested an anti-LPS monoclonal antibody (mAb) in three animal models. 7G is an IgG3 mAb directed against an oligosaccharide side chain determinant of LPS from E. coli 0111:B4. This anti-LPS mAb increased the LD50 of 0111:B4 LPS in mice and protected rabbits against the dermal Shwartzman reaction elicited by 0111:B4 LPS. 7G mAb also protected mice against lethal infection with mucin-enhanced E. coli 0111:B4. Pretreatment with 250 micrograms of 7G increased the LD50 by more than 1.5 logs. These studies prove that oligosaccharide side chain-specific antibody to LPS confers protection against LPS toxicity in vivo and against experimental gram-negative infection. In addition, these studies suggest the potential of anti-LPS monoclonal antibody as therapy for gram-negative infection.
 ...
PMID:An immunoprotective monoclonal antibody to lipopolysaccharide. 620 51

The present investigation reports the production of monoclonal antibodies to antigenic determinants of the O-polysaccharide of Salmonella typhimurium lipopolysaccharide (LPS), and assesses the effectiveness of these antibodies in protecting C3H mice against the lethal effects of Salmonella infection. Hybridomas were generated by fusing spleen cells from (BALB/c X A/J)F1 (CAF1) mice hyperimmunized by i.v. injection with acetone-killed S. typhimurium SR-11 with X63-Ag8.653 murine myeloma cells. Hybridomas producing antibodies reactive with S. typhimurium SR-11 whole cells were subcloned, and seven of the resulting clones as well as one previously described clone were selected for use in the studies reported here. Monoclonal antibodies from these eight clones were of the IgG1 (1), IgG3 (6), or IgM (1) isotype and were specific for the O-polysaccharide region of Salmonella LPS, reacting with LPS from smooth S. typhimurium SR-11 and LT-2, but not with LPS from rough S. minnesota R60 (Ra), R345 (Rb), or R595 (Re). The effectiveness of each monoclonal antibody in protecting C3H/HeN and C3H/HeJ mice against the lethal effects of Salmonella infection was evaluated by comparing the median length of survival of groups of mice given antibody by i.p. injection before i.p. challenge with virulent S. typhimurium SR-11 to that of animals that received no antibody. Three out of eight monoclonal anti-O-polysaccharide antibodies, ST-1 (IgM), 10-5-47 (IgG3), and 10-5-6 (IgG3), provided significant (p less than 0.01) protection to C3H/HeN mice challenged with approximately 10(4) LD100 of Salmonella. Only antibodies ST-1 and 10-5-6, however, extended the median length of survival of C3H/HeJ mice beyond that of infected controls. Mouse antiserum prepared against S. typhimurium SR-11 was equally protective in C3H/HeJ mice. In an attempt to understand the contribution of antibody specificity to the relative differences in the protective capacities of the monoclonal antibodies, their reactivities with several Salmonella reference strains of different classical serotypes were examined. Although some differences in reactivity against the different strains were apparent, this approach was not adequate for defining the fine specificity of these monoclonal antibodies. The results of this study provide evidence that monoclonal antibodies with specificity to the O-polysaccharide region of Salmonella LPS can protect C3H mice against challenge with the homologous bacterial strain.
 ...
PMID:Monoclonal antibodies to Salmonella lipopolysaccharide: anti-O-polysaccharide antibodies protect C3H mice against challenge with virulent Salmonella typhimurium. 620 84

Polyclonal activation of resting B lymphocytes by either lipopolysaccharide or specific helper cells recognizing antigens on B cell membranes results in selective patterns of IgG subclass expression among plaque-forming cells. We have studied the IgG subclasses of plaque-forming cells generated in cultures of purified B cell blasts selected for reactivity to either LPS or helper cells, and restimulated by either lipopolysaccharide, specific helper cells, or as "bystanders", by nonspecific B cell growth factors. Development of IgG1 plaque-forming cells is observed only when clonal expansion is maintained by specific helper cells, whereas IgG3 secretion specifically requires stimulation by lipopolysaccharide and the absence of helper cell activity. Furthermore, exposure of resting B lymphocytes to specific helper cell induces, in 48 h, an irreversible loss of the potential to produce IgG3. Other than showing that helper cell-dependent B cell growth and maturation is more complex than previously suspected, these results suggest that differentiation signals or factors induce specific DNA recombination and deletion events.
 ...
PMID:Immunoglobulin C-gene expression. III. Possible induction of specific genetic events in activated B lymphocytes by the polyclonal stimuli driving clonal expansion. 621 8

It has been reported (Contemp. Top. Immunobiol. 1974. 3:41) that allotype-specific T suppressor cells can be induced after monoclonal anti-allotype treatment of neonatal (BALB/c X SJL)F1 (Igha/b) mice. Here we show that (BALB/c X CB20)F1 adult-derived spleen cells (SC) are, by contrast, potently suppressed by monoclonal allotype-specific reagents, (when transferred into irradiated BALB/c recipients) in the absence of primary T suppressor cell induction. Such suppression is only induced in activated B cells [exposed to lipopolysaccharide or sheep red blood cells (SRBC)], and is probably dependent on the isotype of the anti-allotype sera administered. For example, two independently produced IgG1 monoclonal reagents raised against the Igh-1b allotype were poorly suppressive or nonsuppressive, whereas an IgG3 and an IgG2a monoclonal antibody induced a 90% suppression of the target allotype in transferred adult SC. It was found that suppression was not due to a depletion of antigen-specific T cell help since: (a) the addition of SRBC-educated T cells did not break suppression and (b) suppressed SC were as good a source of T cell help as normal SC, in the response of virgin or memory B cell (Thy-1-depleted) responses to SRBC in vivo. Suppression was maintained in suppressed cells which had been rechallenged with SRBC after transfer into a second irradiated recipient, but was not induced in normal SC when these were admixed with an equal number from this suppressed SC population. These findings point to a possible mechanism for the regulation of B cell expression, through the formation of an antibody-Ig receptor complex at the surface of the B lymphocyte. After complexing the target cell is either deleted or inactivated. The response to SRBC was reduced or ablated for at least 70 days after treatment with a single dose of anti-allotype serum.
 ...
PMID:Antibody-mediated allotype suppression in adult mice: the role of antigen, effector isotype and regulatory T cells. 623 17

The induction of IgG synthesis by normal human lymphocytes in response to a range of B-cell activators has been studied by indirect cytoplasmic immunofluorescence using monoclonal antibodies to the four IgG subclasses. Considerable variation was found between cells from different donors tested with the same activator but the following trends were observed:- Epstein-Barr virus and Branhamella catarrhalis induced a predominantly IgG3 response, whereas the most prevalent cells in cultures stimulated with lipopolysaccharide and Staph. aureus were IgG2-positive; the subclass distribution obtained with pokeweed mitogen resembled that found in normal serum (IgG1 greater than 2 greater than 3 greater than 4).
 ...
PMID:The IgG subclass responses of human lymphocytes to B-cell activators. 631 31

Mouse B lymphocytes can be activated polyclonally by bacterial lipopolysaccharide (LPS) to differentiate into plasmablasts. Within several days many cells perform immunoglobulin (Ig) class switching in vitro. We have purified LPS blasts expressing IgM or only IgG3 on the cell surface and analysed the DNA of these cells by Southern hybridisation blotting to detect rearrangement or deletion of CH genes. Quantitative evaluation of the Southern blots suggests that populations of surface IgG3+ (sIgG3+) cells from 6-day and sIgM+ cells from 8-day-old cultures contain only about half as many Cmu genes as spleen cells. Cmu deletion is nearly complete in populations of sIgG3+ cells from 9-day-old cultures. Therefore, upon stimulation with LPS, within a few days Cmu is deleted in most sIgG3+ cells from both chromosomes.
 ...
PMID:Deletion of Cmu genes in mouse B lymphocytes upon stimulation with LPS. 631 7

Injection of lipopolysaccharide into adult mice results in a rapid increase in the number of splenic IgM-secreting plaque-forming cells (PFC) so that by 60 h they represent roughly 20 times those present in normal mice. Although inhibited for the first two days, IgG3, IgG2b and IgG2a PFC are later selectively stimulated and, by 110 h, they reach numbers that are 100, 40 and 30 times, respectively, those of normal mice. IgG1 PFC are stimulated only marginally and 48 h after the maximal responses of the other IgG subclasses. IgA PFC are selectively inhibited and drop to 20% of normal numbers 4 days after injection. The ability of lipopolysaccharide to selectively stimulate B cells for the production of IgG3, IgG2b and IgG2a was further substantiated by studying athymic mice, and by using adoptive cell transfers that overcome regulatory influences limiting these responses in intact mice. Under these conditions, 16% of all spleen cells are PFC and up to 85% of all Ig-secreting cells are included in those three isotypes. Similar responses are also detected in bone marrow but they occur 24-48 h after the splenic responses, suggesting that bone marrow PFC are not induced in situ. These results demonstrate a selective in vivo isotype commitment in response to lipopolysaccharide that is polyclonal and, therefore, independent of V region specificities.
 ...
PMID:Isotype commitment in the in vivo immune responses. II. Polyclonal plaque-forming cell responses to lipopolysaccharide in the spleen and bone marrow. 633 52

B cell hyperactivity, a feature common to all lupus-prone murine strains, may be caused by hyperresponsiveness to, overproduction of, or bypassing of certain signals required for B cell activation, proliferation, and differentiation. In this study, we have compared the responses of B cells from three lupus-prone strains of mice (BXSB males, MRL and NZB/W females) and normal strains in a number of assays for which two or more signals are required to obtain a response. In medium to low density cultures of B cells from BXSB and NZB/W but not MRL/l lupus mice, the cells' proliferation induced by bacterial lipopolysaccharide (LPS) or anti-mu antibody was much higher than that of B cells from normal controls. At low B cell density, polyclonal activation by these substances and subsequent Ig secretion were dependent on accessory signals present in supernatants of concanavalin A-treated normal lymphocytes (CAS) or on the MRL/l proliferating T cell-derived B cell differentiation factor (L-BCDF) in both lupus-prone and immunologically normal mice. However, the responses of B cells from BXSB and NZB/W, but not MRL/l, mice to these accessory signals were higher than those of normal mice. Ig synthesis by fresh B cells of BXSB and NZB/W mice cultured in the absence of mitogens but in the presence of CAS or L-BCDF was higher than by similar cells from other strains, suggesting an increased frequency of B cells activated in vivo in these two autoimmune strains of mice. The patterns of IgG subclass secretion in response to LPS (without added CAS or L-BCDF) were abnormal in all lupus strains, with a predominance of IgG2b and/or IgG2a and low levels of IgG3, contrary to normal B cells for which IgG3 synthesis predominated. However, IgG1 synthesis in vitro by autoimmune and normal B cells alike was highly dependent on T cell-derived soluble mediators. Antigen-specific responses to SRBC in vitro of B cells from all lupus strains, like those of B cells from normal strains, required a minimum of three signals (antigen, LPS, T cell-derived antigen nonspecific helper factors). Yet, once triggered, B cells of BXSB and NZB/W mice gave higher responses than those of the other strains. We conclude that B cells of lupus mice have signal requirements similar to those of normal mice. Nevertheless, B cells of BXSB and NZB/W, but not MRL/l, lupus mice hyperrespond or process some accessory signals abnormally.
 ...
PMID:B cell dependence on and response to accessory signals in murine lupus strains. 640 39


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