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S Avrameas

Publications and source records attributed to S Avrameas.

At least 55 records · Page 3Linked to original sources
PubMed1993

Specific and natural antibody production during Salmonella typhimurium infection in genetically susceptible and resistant mice.

Genetically susceptible (C57BL/6) and resistant (CBA) mice were infected with an avirulent strain of Salmonella typhimurium and studied over a 35-day period for the production of antibodies directed against bacterial antigens including lipopolysaccharide (LPS) (specific antibodies) and antibodies directed against self antigens [natural antibodies (NAb)]. Antibodies directed against LPS and self antigens were detected by enzyme immunoassay (EIA) and those directed against other bacterial antigens by immunoblotting. We found that serum natural antibody titres in C57BL/6 and CBA mice were similar and correlated with the bacterial load in the spleen and liver. In C57BL/6 mice, anti-LPS antibodies remained polyreactive and of the IgM isotype. In contrast, CBA mice, after an early increase in polyreactive IgM anti-LPS antibodies, mounted a specific anti-LPS IgG antibody response. The immunoblotting results demonstrated that the IgM polyreactive antibodies in the resistant and susceptible mice recognized bacterial antigens of different molecular weights and that CBA, but not C57BL/6 mice, were able to produce IgG antibodies recognizing bacterial components. Our results suggest that the synthesis of antibodies directed against bacterial antigens and natural antibodies follow, at least partially, distinct pathways, but they do not allow us to determine whether these two antibody populations are produced by the same or distinct B-cell subpopulations.

Animals↗
PubMed1992

Natural mouse IgG reacts with self antigens including molecules involved in the immune response.

IgG isolated on protein A-Sepharose from pools of normal sera from various mouse strains were examined by immunoblotting for reaction with self antigens. Homogenates of the major mouse organs, i.e. brain, skin, spleen, kidney, adrenals, thymus, heart, muscle and liver were used as the source of autoantigens. IgG stained at least 220 bands on the immunoblots. The antigens corresponding to these bands were tentatively identified by molecular mass estimation and referenced to computerized mouse protein data banks. IgG mainly recognized enzymes but it also stained intracellular structural constituents and surface molecules implicated in the functioning of the immune system. The validity of this identification was confirmed by analyzing purified antigens from mouse or other animal species by immunoblotting and enzyme immunoassays. Furthermore, extracts of 125I-surface-labeled cells were immunoprecipitated with IgG in the liquid phase or immobilized on beads. The proteins precipitated migrated to the same positions as those precipitated by specific monoclonal antibodies (mAb), such as class I alpha chain and beta 2-microglobulin, class II alpha and beta chains, CD3, CD4 and CD8 antigens. The results obtained with several enzyme immunoassay procedures using cell membrane extracts, specific mAb and normal IgG further supported the specific interaction of IgG with Ia, CD4 and CD8 molecules. Affinity chromatography indicated that at least 20% of normal mouse IgG possess polyreactive autoantibody function. Dissociation constants of these IgG were calculated for some autoantigens and found to be in the range of 2 x 10(-6)-7 x 10(-6) M. It is concluded that normal mouse IgG exhibit autoreactivities similar to those previously described for IgM.

Animals↗
PubMed1992

Molecular characterization of the variable regions of a mouse polyreactive IgG2b antibody with rheumatoid factor activity.

The complete nucleotide sequences of heavy and light chains of a mouse polyreactive IgG2b antibody were determined. This antibody, obtained after primary immunization of BALB/c mice with human lymphoblastoid cells, possess anti-HLA-DR and anti-rheumatoid factor activities and reacts with various self and nonself antigens. The VL and VH segments were found to belong to the VK8 and VH7183 families, respectively. The VH segment shared a high percentage of sequence similarity (95%) with previously described germline genes. The VK segment had 98.9% of sequence similarity with a consensus sequence VK8 of antibodies with anti-phosphorylcholine activity. Furthermore, the framework regions 2 and 3 of the VL segment were very similar to the framework regions 2 and 3 of other antibodies known to possess rheumatoid factor activity. We postulate that during immunization, the presence of HLA-DR antigens selects precursors having configurations similar to that of the germline, and induces some somatic mutations that do not significantly affect antibody polyreactivity.

Amino Acid Sequence↗
PubMed1992

Autoantibodies and circulating immune complexes in sera from patients with hepatitis B virus-related chronic liver disease.

Sera from 56 patients with hepatitis B virus-related chronic liver disease (CLD) and 30 normal individuals as controls were examined by enzyme immunoassay (EIA) for the presence of autoantibodies directed against actin, tubulin, myosin, double-stranded (ds) DNA, polymerized human albumin, thyroglobulin, and trinitrophenyl coupled to bovine serum albumin (TNP-BSA). Patients with CLD had consistently elevated levels of IgG, IgA, and IgM antibodies directed against all the panel antigens. The percentage of patients with autoantibodies of the IgA class was particularly high: respectively, 88 and 78% of the patients had strikingly high levels of anti-actin and anti-TNP-BSA IgA autoantibodies. High amounts of IgA and IgG antibodies to polymerized albumin as well as IgG to thyroglobulin were also detected. Circulating immune complexes (CIC) were isolated from patients' sera and their autoantibody activities were tested on the same antigen panel. The autoantibodies thus detected were of the same class and possessed the same activities, although at higher values than those present in the homologous sera. These results indicate that, regardless of their origin, autoantibodies are present in high amounts in the sera of these patients. Moreover, autoantibodies participating in the formation of CIC might play a pathological role.

Actins↗
PubMed1992

Characterization of a murine immunoglobulin VH gene segment in subgroup III: a new member of the 7183 gene family.

A new gene for the variable region of the immunoglobulin heavy chain (VH gene) has been isolated from BALB/c adult liver DNA using a cDNA plasmid probe containing a mouse VH sequence. The complete nucleotide sequence of this germline gene (VH10-19), shows that it belongs to the 7183 gene family. The VH gene appears to contain an intervening 104-base-long sequence and displays the same recombination signal sequences that those observed in the germline 81X. The presence of an internal heptamer at the 3' end of the VH10-19 coding region let an alternative recombination event that could increase the representation of this gene in the immature repertoire.

Amino Acid Sequence↗
PubMed1992

Spontaneous IgM autoantibody production in vitro by B lymphocytes of normal human neonates.

Human neonate B lymphocytes display unique phenotypic and functional characteristics: in addition to CD1c antigens, CD5+ and CD5- subsets both express activation markers such as CD23 and Bac-1. They proliferate strongly in the presence of various lymphokines (rIL-2, rIL-4, low molecular weight BCGF), but differentiate poorly in the presence of the same lymphokines, pokeweed mitogen and Epstein-Barr virus. It has also been reported that human neonate B lymphocytes produce polyreactive autoantibodies after in vitro activation by Staphylococcus aureus Cowan I and transformation by Epstein-Barr virus. We now show that, in the absence of in vitro stimulation, human neonate B lymphocytes produce polyreactive antibodies of the IgM isotype against several autoantigens. The B lymphocytes involved expressed membrane IgD, IgM, CD23 and CD11b molecules; CD5 expression was variable. This phenotype was consistently found on a minority of B lymphocytes and is similar to that of polyreactive autoantibody-producing B cells in mice. We also found that autoantibody production in vitro could occur in the absence of any T helper effect. The function of these autoantibodies is not clearly established, but their occurrence in a large proportion of human neonates strongly suggests that they play an important role in the development of the immune system.

Adult↗
PubMed1992

Natural autoantibodies in schizophrenia.

Autoantibodies reacting with cell constituents other than antinuclear antibodies have seldom been reported in the literature on schizophrenia. Serum of 41 DSM-III-R schizophrenic patients was examined for the presence of various autoantibodies and compared with that of healthy volunteers (n = 10) and hospitalized controls. Titers of IgG, IgA and IgM autoantibodies directed against actin, tubulin, myosin, DNA, thyroglobulin, elastin, albumin, DNA and trinitrophenyl groups were determined using enzyme immunoassay. IgG and IgA titers were significantly decreased in schizophrenic patients. These results contrast with those obtained with various other autoimmune and nonautoimmune diseases in which titers are either unchanged or increased. A significant increase of various autoantibody levels was observed in the paranoid subgroup of schizophrenics compared with the disorganized subgroup. These autoantibodies possess characteristics similar to those of natural autoantibodies, which seem to play several biological roles.

Adolescent↗
PubMed1992

Preliminary results towards ciguatoxin immunodetection.

Due to the lack of purified ciguatoxin (CTX), monensin was used as a model for developing an enzyme immunoassay to detect CTX. Specific antibodies directed against monensin have been produced in rabbits and mice using a monensin-protein immunogen obtained in bulk quantities. Rabbit polyclonal and mouse monoclonal (MAb) antibodies of high specificity and affinity have been produced. Using MAb 2H8, in a competitive micro-ELISA performed in Terasaki plates, the detection limit for free monensin was 75 pg. No cross-reactivity was detected against CTX but a procedure requiring only 100 micrograms of hapten is under current investigation with a brevetoxin (PbTx-3), another marine toxin with a polyether backbone structure similar to CTX and recently commercially available.

Animals↗
PubMed1992

[Antibacterial resistance induced by injection of ascitic fluid (with IgM partially removed) and natural monoclonal antibodies of human origin in rainbow trout].

Human monoclonal immunoglobulins M from myeloma shown to have the typical polyspecificity of natural antibodies, were precipitated from the ascitic fluid that originally contained them. The IgM and their supernatant were injected in parallel, intraperitoneally into rainbow trout (Oncorhynchus mykiss) to test passive protection against experimental furunculosis. Protection was observed in both cases (significant protection at 2%). However, only trout treated with IgM were still protected against polybacterial cross-infections which occurred 10 days later (significant protection at 1%). These results confirm the passive mammalian protection conferred by biologic fluids injected in vivo in fish and provide further evidence for participation of natural antibodies in antibacterial defences.

Animals↗
PubMed1991

Ig repertoire of human polyspecific antibodies and B cell ontogeny.

A total of 463 EBV Ig-secreting clones were derived from embryonic tissues, cord blood, and adult peripheral blood. Subcloning and analysis of the H and K loci (germline vs rearranged DNA status) of 44 primary clones insured clonality in at least 92% of cases. Whatever the cell origin, a somewhat constant proportion of clones (i.e., 11 to 16%) expressed polyspecific antibodies when tested on a panel of nine Ag, including self-Ag. The VH and VK repertoires have been studied using VH1-VH6 and VK1-VK4 family-specific probes. For all EBV clones the VH and VK utilization was similar to that of the normal untransformed population. A correlation was observed between the level of expression and the gene number for VH, whereas a clear distortion appeared for VK. Moreover, the usage pattern of VH and VK families of the polyspecific clones did not significantly differ from that of clones of unknown specificity, suggesting that polyspecificity was not linked to a restricted repertoire.

Adult↗
PubMed1991

Comparison of natural antibodies to autoantibodies arising during lupus in (NZB x NZW)F1 mice.

Autoantibodies arising in (NZB x NZW)F1 (B/W) mice during the lupus-like syndrome were studied and compared to natural antibodies present in normal mice. The antibody activities were tested in sera, circulating immune complexes (CIC) and kidney eluates, using an enzyme immunoassay against a panel of self and non-self antigens: actin, myosin, tubulin, DNA, myoglobin, spectrin and trinitrophenylated bovine serum albumin (TNP/BSA). In the B/M mouse sera, IgM antibodies reacting with all the panel of antigens (PAg) and comparable to those of normal mice, increased moderately from 5 to 9 months and markedly during the last stage preceding death (10 months), when particularly high levels of anti-DNA, anti-tubulin and anti-myoglobin antibodies were noted. Polyreactive IgM antibodies present in CIC were moderately increased while those present in complexes deposited in kidneys were strongly enhanced after the 8th month. IgG antibodies showed an early increase (2 months) in B/W sera for anti-TNP activity, which remained more or less constant until death, while a later (5-6 months) and greater increase of activity, mainly directed against DNA but also against the other antigens of the panel, was observed. In CIC, IgG, mainly anti-DNA but also anti-TNP, were enhanced at the end of the disease while at the same time IgG reacting with all the PAg were found in kidney deposits. Isolation of antibodies from sera on a DNA-immunoadsorbent demonstrated that eluted IgM reacted with all the PAg but mainly with DNA, while IgG reactivity was more restricted to DNA and to a lesser degree to TNP. The D23 idiotype, characteristics of natural polyspecific antibodies, was expressed on IgM and IgG autoantibodies from B/W mice and was enhanced, particularly in kidneys, at the end of the disease. These results demonstrate that natural antibodies are a part of the population of increased autoantibodies in this disease and could participate with IgG anti-DNA antibodies in lupus.

Animals↗
PubMed1991

Visualization of natural autoantibody polyreactivity by rotary metal-shadowing electron microscopy.

Immune complexes formed by mouse polyspecific natural autoantibodies and various structurally different antigens, such as DNA, tubulin and myosin, were analysed by rotary-shadowing electron microscopy. Each of the four natural IgM autoantibodies studied (E7, D23, 3C3 and M2-9) recognized multiple epitopes on the myosin molecule. These results, confirmed by immunoblotting experiments using myosin subfragments as antigens, strikingly contrasted with those obtained with an induced myosin-specific IgG antibody which interacted with a single myosin antigenic site. Based on the measurements of the antibody position on the antigen, made on a series of electron micrographs, two negatively charged myosin peptides were prepared by solid phase synthesis. Polymeric forms of one of the two peptides interacted with the positively charged CDR part of E7 and inhibited the binding of E7 and M2-9 to myosin. The importance of charge in the observed cross-reactivities was further supported by enzyme immunoassays showing that most, but not all, antigen/natural autoantibody interactions were sensitive to increasing concentrations of NaCl.

Actins↗
PubMed1991

Natural autoantibodies: from 'horror autotoxicus' to 'gnothi seauton'.

The immune system of normal unimmunized animals is characterized by the presence of B cells synthesizing and secreting mainly polyreactive, but also monoreactive, IgM and IgG natural antibodies that can react with a variety of self constituents. These antibodies, like the autoantibodies appearing in several immunopathological states, use the same genetic elements as the antibodies directed against environmental antigens, and seem to be encoded by unmutated germ-line genes. Accumulating evidence indicates that these natural auto-antibodies exert various biological roles, both related and unrelated to the immune system. In this article, Stratis Avrameas proposes that natural auto-antibodies, by interacting with the large number of self constituents present in an organism, establish an extensive dynamic network that contributes to the general homeostasis of the organism.

Animals↗
PubMed1991

Induction of high levels of IgG autoantibodies in mice infected with Plasmodium chabaudi.

This study analyzed the effect of infection of mice with a virulent strain of Plasmodium chabaudi on natural autoantibodies. Mice received appropriate treatments in order to survive and the serum autoantibodies were characterized either by enzyme immunoassays against a panel of self and non-self antigens or by Western immunoblots using fibroblast or red blood cell (RBC) extracts. IgM and mainly IgG antibodies directed against actin, myoglobin, myosin, spectrin, tubulin, and trinitrophenylated-ovalbumin were found a few days after the parasitemia peak, persisted for several weeks after parasite clearance, and returned to almost normal levels after 2 months. Following a challenge with parasitized RBCs, a similar increase in all antibodies was observed, their levels remaining high 20 days post-injection and still remaining at twice the normal level 1 month later. Western blotting detected autoantibodies to many membrane RBC proteins, e.g. spectrin, and band 3 and its related polypeptides, as well as against fibroblast constituents, such as tubulin, actin, and the 70 kd heat shock protein. Autoantibodies seemed to be polyspecific, since those eluted from infected mouse RBCs and the IgG antibodies from infected mouse sera affinity-purified on a mouse tubulin immunoadsorbent reacted with all antigens of the panel, including parasite extracts. Surprisingly, in mice which had recovered from infection, autoantibody levels, particularly anti-spectrin and anti-band 3, rose after the injection of a high dose of normal instead of parasitized RBCs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Biased amino acid distributions in regions of the T cell receptors and MHC molecules potentially involved in their association.

We have analysed, in the context of the available structural information, the frequency of occurrence of different amino acids in functional regions of both the class I MHC antigens and of the TCR alpha and beta chains. We found that in class I MHC molecules, charged residues are found frequently among those which are presumably dedicated to interactions with the TCR, while the aromatic side chain residues are found more in the interior of the groove. In the TCR, the Asn residue appears with high frequency in all the CDR equivalents. The TCR CDR3s of both alpha and beta chains are particularly rich in Gly, whereas the CDR1 and CDR2 loops exhibit strong biases in favour of charged residues. Accordingly, the interactions between the MHC molecule and the peptide antigen appear to be essentially mediated by hydrophobic interactions and hydrogen bonding, while electrostatic interactions between charged residues might be important in the association of TCR and MHC molecules. The observation that each CDR1 and CDR2 is biased towards a particular set of amino acids, taken together with the nature of the protruding residues on the MHC helices, allows us to propose, in the frame of a molecular model of the MHC-TCR complex, several plausible configurations.

Amino Acid Sequence↗
PubMed1991

Syngeneic albumin can be used as a carrier in neonatal mice.

Free native horseradish peroxidase (PO) or PO coupled to either syngeneic mouse serum albumin (PO-MSA) or to xenogeneic bovine serum albumin (PO-BSA) in sterile phosphate buffered saline (PBS), were injected repeatedly into newborn BALB/c mice. Serum antibody titres were evaluated by enzyme immunoassay on 30 and 60 of age and on d 75 and 88 after 1 or 2 booster injections respectively. The response to PO was found in all sera from neonatal immunized mice with all forms of PO, but only in control adult mice immunized by PO-BSA. Immunization with either PO-MSA or PO-BSA induced mainly IgG anti-PO antibodies of high avidity while immunization with free PO resulted in the induction of both IgM and IgG anti-PO antibodies of low avidity. A large number of hybridomas with anti-PO specificity were obtained from the spleen of mice injected with PO-MSA. The results indicate that neonatal immunization of mice with PO is an effective procedure, which is probably applicable to other proteins.

Animals↗