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Biomedical subjects

S Avrameas

Publications and source records attributed to S Avrameas.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1990

IgG autoantibody activity in normal mouse serum is controlled by IgM.

In the serum of normal BALB/c mice, IgG antibody reactivity to mouse actin and tubulin, DNA, and TNP groups was very low compared to that of the IgM. This activity was considerably increased when IgG was separated, by affinity chromatography on protein A-Sepharose, whereas no difference in the IgM activity was observed. Addition of IgM to IgG isolated from the same serum resulted in the inhibition of IgG binding to these Ag. Isolation of IgG antibodies on actin, TNP, and tubulin immunoadsorbents has indicated that at least part of the IgG antibodies is polyreactive. In order to understand this inhibition better, experiments with F(ab')2 fragments of IgG were performed. IgM inhibited the binding of F(ab')2 to the antigens in a dose-dependent manner and reacted with immobilized F(ab')2. IgM isolated on F(ab')2 immunoadsorbent, as compared to the initial IgM preparation, were less active toward the Ag but more inhibitory for IgG binding to the Ag. In some pathologic situations, IgM failed to inhibit some IgG antibody activities. The anti-DNA IgG activity from (NZB x NZW)F1 mice was not affected by autologous IgM. Similarly the anti-tubulin IgG from mice infected with Trypanosoma cruzi were less inhibited by IgM from autologous serum than antitubulin IgG from normal mice. These results are compatible with the existence in normal mice of an idiotypic-like network, regulating via an IgM population in the serum, the binding of IgG autoantibodies to self Ag. Modifications of this idiotype-anti-idiotype system might lead to the expression and/or expansion of autoreactive IgG-producing clones.

Actins↗
PubMed1990

Comparison between autoantibodies arising during Trypanosoma cruzi infection in mice and natural autoantibodies.

The autoantibodies induced in (C57BL/6 x BALB/c)F1 mice during Trypanosoma cruzi (CL strain) infection were analyzed and compared with natural autoantibodies present in healthy mice. Mice were killed at intervals after infection and their sera were tested by enzyme immunoassay against a panel of self- and non-self-Ag: actin, myoglobin, myosin, tubulin, DNA, and TNP-OVA. The level of IgM and IgG autoantibodies against all Ag started to increase from day 15 until 6 wk after the parasite infection. The high level of all autoantibodies persisted 3 mo postinfection, and 1 yr later, half of the mice still had elevated levels of IgM and IgG autoantibodies, particularly antitubulin IgG antibodies. IgM and IgG were isolated from pools of normal and infected mouse sera and their binding capacity to all Ag was compared. The titers of infected mouse sera were increased and the slopes of both IgM and IgG binding curves of autoantibodies to actin, myosin, and tubulin were greater than those of control mouse sera, indicating higher affinities. The average dissociation constant of the IgG2a autoantibody to mouse tubulin was 5 times lower than that of natural antitubulin IgG2a antibodies. Furthermore, absorption of the IgG from infected mouse sera onto a tubulin immunoadsorbent removed half the reactivity with tubulin and also with myosin, actin and parasite extracts. The eluted antibodies bound the same Ag. When IgG were further analyzed by Western blot on proteolytic fragments of tubulin, we found that antibodies from both groups bound to the same broad spectrum of polypeptide bands. However, additional fragments were recognized by antibodies from infected mice. All these results indicate that the autoantibodies naturally present in mice are significantly affected after infection with T. cruzi, in quantity as well as in specificity and affinity.

Animals↗
PubMed1990

Idiotypic interactions between normal human polyspecific IgG and natural IgM antibodies.

Pooled normal human polyspecific IgG (IVIg) contain anti-idiotypes against a variety of autoantibodies from patients with autoimmune diseases and IgG autoantibodies present in IVIg. The present study indicates that IVIg may also react through idiotypic/anti-idiotypic interactions with human natural IgM antibodies. Sixty-four percent of IgM secreted by B lymphoid cell lines derived from B cells of healthy elderly donors and 18% of IgM secreted by cloned EBV-transformed cord B cells that were tested, bound through their variable region to F(ab')2 fragments of IVIg. The binding to 2,4,6-trinitrophenyl (TNP) of a polyreactive IgM with anti-TNP specificity, was inhibited by F(ab')2 fragments from IVIg, indicating the presence in IVIg of anti-idiotypes that may interfere with the antibody-combining site of polyreactive IgM antibodies. The ability of IgM antibodies to interact with idiotypes on IVIg was not related to the degree of polyreactivity of natural antibodies. Our observations further document that IVIg contain antibody specificities against Ig from normal individuals and suggest that IgG originating from the physiologically expressed repertoire may modulate the expression of the potential B cell repertoire. The results may be relevant to the suppressive effect of IVIg in autoimmune diseases.

Antibody Specificity↗
PubMed1990

Poly(Glu60Ala30Tyr10) (GAT)-induced IgG monoclonal antibodies cross-react with various self and non-self antigens through the complementarity determining regions. Comparison with IgM monoclonal polyreactive natural antibodies.

Previous studies have shown that the antibodies of the preimmune repertoire are able to bind to various auto- and xenoantigens including chemical haptens. Sequence analysis of two such murine monoclonal IgM natural autoantibodies showed that they are encoded by unmutated germ-line variable regions of the light and heavy chain (V alpha and VH) genes which were also found in various murine immune responses, like phenyl-oxazolone, dinitrophenyl, arsonate, phosphorylcholine and influenza virus hemagglutinin. These data raised the question as to whether induced antibodies possessing germ-line sequence are also able to react with autoantigens. To study this problem, anti-poly(Glu60Ala30Tyr10) (GAT) and anti-alprenolol (Alp) monoclonal antibodies, carrying similar VH and V alpha genes and the same IgG1 isotype, were examined for their capacity to react with several self and non-self antigens. The results showed that: (a) the anti-GAT antibodies tested reacted with different autoantigens, such as murine tubulin, actin and myosin as well as trinitrophenyl (TNP) and bovine serum albumin. Similarly, one of the anti-Alp showed weak reactivities for myosin, DNA, actin and TNP; (b) in contrast two other anti-Alp antibodies did not react with any of the tested antigens. Since the major differences between the oligoreactive anti-GAT and the monoreactive anti-Alp antibodies are in the complementarity determining regions (CDR) our results suggest that the observed cross-reactions are mediated by hypervariable loops. Sequence comparison of these antibodies indicate a possible correlation between cross-reactivity and the presence of aromatic and charged amino acids in the CDR.

Amino Acid Sequence↗
PubMed1990

Antibodies to viral antigens, xenoantigens, and autoantigens in Alzheimer's disease.

Sera from 19 patients with Alzheimer's disease (AD) and 21 control subjects were studied by immunofluorescence and enzyme immunoassay for antibody activity against various viruses and 12 self- and non-self-antigens. Total IgG mean level was significantly higher in the AD group; the IgG level was above 15 g/L in 52.8% of AD patients versus 14.3% of control subjects. Antiviral antibody titers showed no significant differences except for antibodies to herpes simplex virus-1, which were increased in control group. In contrast, autoantibodies were more frequently found in AD patients, and the prevalence of antibodies to spectrin, peroxidase, and thyroglobulin was significantly increased. Thus, in our series, autoimmune but not antiviral responses were heightened in at least 42% of AD patients (versus 9% of the control group) suggesting the existence of two subpopulations in the AD group.

Adult↗
PubMed1990

IgA polyspecific autoantibodies in IgA nephropathy.

The specificity of circulating and kidney-bound IgA during IgA nephropathy is still a matter of discussion. In the present study, high levels of IgA antibodies directed against a panel of self and non-self antigens were found in the serum from patients with IgA nephropathy and were eluted from four out of the seven kidney biopsies studied. After immunoadsorption of pooled selected serum samples on TNP and actin-coated columns, polyspecific IgA antibodies were eluted. This supports the hypothesis that IgA-bearing B cells clones most probably producing polyspecific antibodies are a major feature of human IgA nephropathy. These findings also suggest that it may be hazardous to draw conclusions from the finding of apparently monospecific IgA antibodies in this condition.

Adolescent↗
PubMed1990

A concurrent increasing of natural antibodies and enhancement of resistance to furunculosis in rainbow trout.

In order to compare the respective roles of specific response and non-specific mechanisms in the enhancement of resistance to furunculosis, 2 groups of rainbow trout (Oncorhynchus mykiss) were immunized with supernatants of Aeromonas salmonicida or Escherichia coli cultures. The fish received 4 weekly intraperitoneal injections (70 micrograms of crude proteins). One control group was injected with phosphate-buffered saline, while another was untreated. Specific agglutinins were produced only in the fish immunized with A salmonicida supernatant. Polyspecific natural antibodies were measured using different antigens in an enzyme immunoassay. A significant rise (up to 3 times the mean titer of untreated controls) was observed in the 3 injected groups (even with PBS), which also displayed significant protection against experimental furunculosis (32 to 42% mortality versus 72% in controls). Thus, although the exact significance of natural antibodies still has to be confirmed, the importance of natural defenses and the difficulty in clearly inducing specific protection against furunculosis are confirmed.

Aeromonas↗
PubMed1989

Immunochemical studies of a murine polyreactive IgG2b autoantibody with rheumatoid factor activity.

The hybridoma, 62H3, which secretes a monoclonal IgG2b with anti-HLA-DR specificity, was expanded in pristane-primed BALB/c mice and the antibody was isolated from the ascitic fluid by affinity chromatography on Protein A-Sepharose. The purified IgG2b antibody was tested by an enzyme immunoassay for antibody activity against a panel of 40 self and non-self antigens. It was found to react strongly with beta-galactosidase, actin, glutamate dehydrogenase, rabbit and human IgG and di- and trinitrophenyl groups; and moderately with tubulin, insulin and phosphorylcholine; but it did not react with various other self and non-self antigens, such as DNA, albumin, keyhole limpet hemocyanin, hen lysozyme and horseradish peroxidase. Fab and Fc fragments were prepared from this IgG2b by papain proteolysis. The Fab fragment possessed the same spectrum of polyreactivities as the native IgG2b, whereas no activity was detected with the Fc fraction. In order to investigate the properties of the antigen binding site, the actin, TNP and rabbit IgG antibody activities were studied in more detail by enzyme immunoassay, Western blot and immunocytochemistry. The monomolecular nature of this multireactivity was confirmed by immunoabsorption analysis. Furthermore, 62H3 monoclonality was also verified by comparative isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis with other monospecific antibodies. The dissociation constants (Kd) of antigen-antibody equilibria in solution were measured. The Kd for actin was 1.11 +/- 0.24 x 10(-5) M and the Kd for TNP-BSA was 8.7 +/- 0.51 x 10(-7) M. No interaction with rabbit IgG could be detected in solution. These findings raise the question of the possible implication in autoimmune pathology or in normal physiology of IgG class polyspecific antibodies with solid-phase restricted cross-reactive rheumatoid factor activity.

Animals↗
PubMed1989

Anti-tubulin antibodies in rabbits before and after immunization with pig tubulin.

Sera from rabbits before and after repeated injections of pig tubulin in complete Freund's adjuvant were examined for antibody activity against pig and rabbit tubulins and against a panel of antigens: actin, myosin, DNA, TNP/BSA. Antibody activity against all the antigens of the panel (PAg) increased moderately after the first but not after subsequent injections. Antibody activity against pig and rabbit tubulins strongly increased after the second immunization when the maximum was reached. Isolation of anti-tubulin antibodies from normal or immune sera on tubulin-immunoadsorbent demonstrated the presence of three different antibody populations: (1) polyspecific IgM reacting with the PAg and the tubulins, present in substantial amounts in normal sera and moderately increased in immune sera; (2) small amounts of polyspecific IgG detected only in immune sera; (3) high amounts of specific IgG reacting with pig and rabbit tubulins, present in immune but not normal sera. Western blot analysis of the specific IgG population showed that it contained antibodies reacting with both native pig and rabbit tubulins, as well as antibodies recognizing only the 30,000 proteolytic fragment of pig, but not that of rabbit tubulin. The results indicate that the immunization of rabbits with heterologous tubulin induced specific IgG anti-tubulin antibodies which recognize the self and non-self antigens differently.

Animals↗
PubMed1989

Natural autoantibodies in nude and normal outbred (Swiss) and inbred (BALB/c) mice.

Spleen cells from adult unprimed outbred (Swiss) and inbred (BALB/c) mice, either normal (no) or athymic-nude (nu) as well as spleen cells from Swiss nude mice bearing two different human tumors (BUR and PINQ), were fused with the mouse non-secreting myeloma cell line P3X63 Ag8-653. The supernatants of immunoglobulin secreting hybrids, all containing IgM, were screened for antibody activity against macromolecular antigens (autologous: actin, tubulin, myosin, dsDNA) and haptens (TNP, NP, NIP and NBrP). Furthermore, their idiotypic determinants were analyzed using a rabbit anti-idiotype which recognizes a major cross-reactive idiotype (IdD23) of BALB/c natural polyreactive autoantibodies. In all the mice studied, we identified: (1) hybrids reacting strongly with one or more haptens (10.7 to 37.8%) and (2) hybrids secreting natural monoclonal autoantibodies (NMoAb) with broad reactivities (polyreactive and/or oligoreactive) against autoantigens and/or haptens (11.4 to 26.8%). The results indicate that: (1) cells secreting natural autoantibodies with broad reactivities exist in both normal and nude mice, independently of the genetic background (inbred/outbred) of the mouse. However, in nude mice, the natural autoantibodies exhibit a more restricted pattern of reactivity (oligoreactive) compared to those of normal mice, and do not express the common idiotype IdD23 of natural polyreactive autoantibodies. (2) Tumors grafted into nude mice seem to induce the expression of polyreactive autoantibodies bearing the IdD23.

Animals↗