Search PubMed⌕ Search

Biomedical subjects

J Pillot

Publications and source records attributed to J Pillot.

At least 109 records · Page 6Linked to original sources
PubMed1987

Restricted heterogeneity of polyclonal rheumatoid factors.

The electrophoretic pattern of rheumatoid factor (RF) was investigated in 40 polyclonal sera, by using radiolabeled IgG. Thirty sera specifically bound IgG aggregates, correlating with their RF titer. The binding pattern was monoclonal or oligoclonal. The molecules responsible were classic RF antibodies, as shown by using purified IgM, inhibition experiments, and by the optimal size of aggregates (2,000-4,000 kd). These data show that RF heterogeneity is restricted in polyclonal sera, and this can have a bearing on several mechanisms.

Antibodies↗
PubMed1987

Antibodies to synthetic peptides from the pre-S1 and pre-S2 regions of one subtype of the hepatitis B virus (HBV) envelope protein recognize all HBV subtypes.

Immunodominant B and T cell epitopes have been demonstrated recently on the preS1 and PreS2 regions of the hepatitis B virus (HBV) envelope protein. Synthetic peptide analogs corresponding to the preS2 region elicit virus-neutralizing antibodies and protect chimpanzees against HBV infection. Antibodies raised by immunization with peptides derived from the preS1 sequence block the site involved in HBV attachment to cell receptors, and are expected to be virus-neutralizing. Results presented here show that antisera raised against synthetic peptide analogs carrying the immunodominant epitope of the preS1 and preS2 sequence, respectively, and corresponding to two HBV subtypes, adw2 and ayw, each recognized preS1 and preS2 specific epitopes on all serological subtypes of the HBV envelope protein. Thus, the sequence variability within the preS1 and preS2 regions does not represent an impediment to the development of synthetic peptide or genetically engineered hepatitis B preS immunogens for worldwide immunization.

Amino Acid Sequence↗
PubMed1987

IgM reassociation in the absence of J-chain.

Human monoclonal IgM pentamers with different biophysical properties (euglobulin, pseudoglobulin or cryoglobulin) were reduced and reassociated in the absence of J-chain. Reassembly occurred for 50-82% of the monomers. The reassociated molecules consisted of covalent oligomers and pentamers. The deficiency of J-chain (estimated to be less than 0.17% of normal) was shown by alkaline-urea overloaded gel electrophoresis followed by silver staining. The addition of exogenous J-chain, from polymeric IgA or IgM, did not significantly modify the reassembly ratio. Thus J-chain does not seem to be an absolute requirement for IgM polymerization.

Humans↗
PubMed1987

Antigenic mapping of the surface proteins of infectious hepatitis B virus particles.

To identify further the surface proteins of the native virus, hepatitis B virus (HBV) particles purified from HBe antigen (Ag)-positive human sera were used as immunogens to produce murine monoclonal antibody (MAb)-secreting hybridomas. The specific binding of antibodies to the HBV envelope (env) proteins was determined in indirect radioimmunoassay and by Western blot analysis. Six MAbs directed against major hepatitis B surface antigen (HBsAg) recognized conformational epitopes on S proteins (P24s/GP27s). Three preS2-specific MAbs reacted with the middle env proteins (GP33s/GP36s) in the 22 nm HBsAg spherical particles. One MAb, F222, was found to react specifically with the two very large (VL) HBV surface proteins with Mr 54K and 66K. The epitope recognized by F222 was located on the protruding N terminus which, in the assembled virus particles, was readily split off by trypsin or V8 protease treatment. The presence of these VL proteins appeared to correspond to the presence of the large env proteins (P39s/GP42s). The data described here indicate that F222 probably recognized an assembled topographic site which could be involved in virus entry into hepatocytes. Moreover, our results suggest that the preS-coded part of the HBV env proteins, which is sensitive to proteases in vitro, could be unstable in vivo and stabilized by immunoglobulins.

Antibodies, Monoclonal↗
PubMed1987

In vivo and in vitro immunosuppressions in mice by a 100-110-Kd fraction from boar seminal plasma.

The activity of a 100-110-Kd immunosuppressive fraction (ISF), isolated from boar seminal plasma, was investigated in mice. In vitro, this fraction was found to inhibit a unidirectional mixed lymphocyte response and cell-mediated lymphocytotoxicity, as well as antisheep red blood cells (T-dependent) and antitrinitrophenylated lipopolysaccharide (T-independent) responses. The ISF also inhibited the macrophage phagocytosis of erythrocytes coated with IgG antibodies, but it did not suppress the natural killer activity. In vivo, ISF was found to lower both the primary responses to T-dependent and to T-independent antigens. Trypsin or pronase digestion of ISF provided active molecules of 30 Kd or 2-5 Kd respectively, thus showing that the activity is due to a protein. This ISF factor, capable of suppressing a wide variety of immune functions and remaining active after cleavage by proteases, could play a role in the lack of immune response against the spermatozoa present in the sow genital tract after intercourse. The use of this factor as a therapeutic agent in humans could eventually be considered after further molecular characterization.

Animals↗
PubMed1987

Reduction of the observed prevalence of so-called non-A non-B hepatitis using sensitive markers of HBV and herpes viruses infections.

In the absence of a specific marker, the observed prevalence of so called non-A non-B hepatitis depends on the sensitivity of the markers of the other viral infections known to induce hepatitis. We have reevaluated this prevalence after using sensitive markers of HBV (HBs monoclonal radioimmunoassay M-RIA and IgM anti-HBc), EBV (IgM anti-VCA), CMV (IgM anti-CMV) and HSV (IgM anti-HSV) in a group of 53 subjects usually considered as having acute or chronic hepatitis. Detection of IgM against HBc, CMV and HSV used immunocapture tests. Among the 37 patients with acute hepatitis, 11 (30 p. 100) were positive for at least one sensitive marker, including 10 markers of HBV (7 M-RIA and 3 IgM anti-HBc) and one IgM anti-CMV. Among the 16 patients with chronic hepatitis, one was positive for HBV by M-RIA; five patients had a false positive reaction to EBV (IgM anti-VCA) disappearing when rheumatoid factor was eliminated. This study shows that many cases of the so-called non-A non-B hepatitis are in fact due to HBV or to a variant of HBV. Definition of non-A non-B hepatitis must include subjects negative for HBV by M-RIA and IgM anti-HBc and negative for CMV by IgM anti-CMV.

Acute Disease↗
PubMed1987

[High prevalence of infection by hepatitis B virus and HIV in incarcerated French drug addicts].

This clinical and biological study was undertaken to assess the prevalence of infection by HIV, HBV and HDV in male drug abusers entering a prison. One hundred and thirteen drug users accepted to be tested: 14 (12 p. 100) were homosexual; 12 (11 p. 100) consumed more than 80 g per day of alcohol. The mean duration of drug addiction was 5 +/- 2.9 years; 50 (44 p. 100) declared having used a personal syringe while 63 (56 p. 100) usually shared their syringe. Serum activity of transaminases higher than twice the normal value was noted in 36 cases (32 p. 100). One hundred and two (90 p. 100) drug abusers had a HBV marker, 17 (15 p. 100) were HBs Ag carriers, 9 had anti-HBc antibody alone. The prevalence of antibodies to the HDV was 23 p. 100 and was higher among the HBs Ag carriers (65 p. 100). There were no cases of AIDS. Clinical examination showed lymphadenopathy in 49 cases (43 p. 100), a weight loss of more than 10 p. 100 in 47 cases (42 p. 100), and in 69 cases (61 p. 100), HIV positive serology, confirmed by Western blot. The duration of drug addiction was longer in the 102 drug users with HBV markers. Long duration of drug abuse and the use of a shared syringe increased the risk of HIV infection. No relation was noted between the presence of HBV markers and HIV positive serology. In this population the prevalence of HIV, HDV markers and HIV infection was high, but no relation with the duration of previous incarceration or homosexuality was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1986

Both Fc alpha domains of human IgA are involved in in vitro interaction between secretory component and dimeric IgA.

The sites of interaction between 125I labelled human secretory component (SC) and dimeric IgA were located by studying the inhibitory effect of various antibodies to IgA. Several Fab' fragments were isolated from three sera of hyperimmunized rabbits. The specificity of these different antibody preparations, as determined by a RIA inhibition test or by ELISA, showed that two were directed against both domains of Fc alpha, two against C alpha 2, two against C alpha 3 and one against Fd alpha. A monoclonal antibody against C alpha 3 was also used. The results indicate that both the C alpha 2 and C alpha 3 domains are equally and independently involved in the interaction between SC and dimeric IgA.

Animals↗
PubMed1986

[Bereavement].

Explore the source record for details and available documents.

Depressive Disorder↗
PubMed1986

Monoclonal antibody recognizing pre-S(2) epitope of hepatitis B virus: characterization of pre-S(2) epitope and anti-pre-S(2) antibody.

A hybrid cell line producing monoclonal antibodies recognizing an epitope encoded by the pre-(S)2 region of hepatitis B virus (HBV) genome was obtained by fusion of mouse myeloma cells with lymphocytes from mice immunized with HBV. The monoclonal antibody Mo-F124 secreted from the hybrid line reacted with the pre-S(2) epitope expressed on the surface of both viral and recombinant HBsAg particles--pre-S(2) and S gene product--localised on 34 kD glycoprotein of the viral envelope. The pre-S(2) epitope was sensitive to digestion with V8 protease from Staphylococcus aureus. The enzyme abolished reactivity with Mo-F124 and polymerized human serum albumin (pHSA) binding activity of recombinant particles. Mo-F124 antibody was used to develop highly sensitive radioimmunoassays for determination of pre-S(2) epitope and anti-pre-S(2) antibody in sera of hepatitis B patients. Detection of a pre-S(2) epitope by the monoclonal antibody-based assay in the early phase of acute HBV infection correlated well with the presence of markers of active viral replication (HBeAg, HBV DNA). The appearance of anti-pre-S(2) antibody, usually in the third month after onset of symptoms, was followed by elimination of circulating HBsAg and seroconversion to anti-HBs in all tested cases of uncomplicated acute hepatitis followed by recovery. Anti-pre-S(2) response was not observed in patients with chronic hepatitis B or acute HBV infection progressing to chronic disease. The observed correlation of anti-pre-S(2) response with recovery suggests that the pre-S(2) epitope may represent one of the epitopes inducing antibodies that neutralize the hepatitis B virus.

Acute Disease↗
PubMed1986

Immunochemical structure of the hepatitis B surface antigen vaccine--II. Analysis of antibody responses in human sera against the envelope proteins.

Antibody responses to the three envelope (env) proteins of hepatitis B viral particles (HB-VP): the S-encoded P25 polypeptide; the pre-S(2)- and S-encoded GP33/GP36 polypeptide; and the large entire env gene (pre-S + S) product, P39/GP42, were investigated using a Western immunoblotting assay (WIBA). HB-VP proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and transferred to nitrocellulose by electroblotting were used as antigenic probes to determine the polypeptide specificity of these antibodies present in immune individuals. Antisera from human subjects either after a natural HBV infection or after active immunization with the hepatitis B vaccine licensed in France were selected on the basis of a positive serological RIA test for antibodies against hepatitis B surface antigen (HBsAg). In all studied cases, the lack of reactivity of the anti-HBs/P25 antibodies in blots from reduced SDS gels confirms that the S-related-determinants have a conformation sensitive to denaturing agents. In contrast, the anti-pre-S(2)/GP33-GP36 antibodies and the anti-pre-S(1)/P39-GP42 antibodies can be easily detected in WIBA, providing these antibodies recognize the disulfide-bond independent pre-S determinants on the denatured env proteins. However, antisera raised in guinea-pigs against individual HBsAg polypeptides contain antibodies reacting with denatured S-proteins, suggesting that the sequential S-determinants are lost during HBV morphogenesis. Antibody responses in HBV convalescing patients or vaccinated healthy donors are shown to be characterized by: an early transient polypeptide specific-antibody response to pre-S(2)-sequences (detected in WIBA); a persistent antibody response to conformation-dependent S-determinants (detected in RIA). This implies that effective long-term protection against HBV infection requires antibodies directed to native env proteins.

Chromobox Protein Homolog 5↗
PubMed1986

Human secretory component. IV: Antigenic regions involved in in vitro binding to dimeric IgA.

The aim of this report was to identify the region(s) of the secretory component (SC) molecule involved in in vitro binding to dimeric IgA. Inhibition of the SC binding was tested by Fab' antibody fragments directed against the accessible (A) and inaccessible (I) regions of SC. Antibodies directed against the main 38.5-kDa trypsin fragment of SC, and antibodies from two immune sera with a wide anti-SC spectrum, were also used. The specificity and activity of the five antibody preparations were established by double-diffusion in gel and by their SIgA combining capacity. Inhibition curves were established by RIA using constant amounts of 125I SC, dimeric IgA and increasing quantities of the various Fab' antibodies. These results indicated involvement of a larger part than the I region of the SC molecule in combination with dimeric IgA, perhaps including a second (minor?) site of binding on the accessible parts in addition to the major region located on I.

Antibody Specificity↗
PubMed1986

Human Fc(gamma) receptors for differentiation in throat cultures of group C "Streptococcus equisimilis" and group C "Streptococcus milleri".

The biochemical characteristics and the presence of human Fc(gamma) receptors of 52 throat isolates of group C beta-hemolytic streptococci were examined. Among these isolates, 38 were identified as "Streptococcus milleri" and 14 were identified as "Streptococcus equisimilis." The differentiation of group C "S. equisimilis" from "S. milleri" with identical group antigens was easy to perform by the measurement of the size of the hemolytic zone on a sheep blood agar plate in an anaerobic atmosphere and by biochemical tests (Voges-Proskauer test). A clear-cut criterion for differentiation was noted among these isolates, i.e., the presence of Fc(gamma) receptors. "S. equisimilis," which are generally associated with pharyngitis, possess human Fc(gamma) receptors, while "S. milleri", which are generally isolated from healthy persons, have no such receptors.

Humans↗
PubMed1986

[Demonstration of a 100-110 kd immunosuppressive fraction in the seminal fluid of swine].

The boar seminal fluid was fractionated in order to purify semen immunosuppressive factors. This species was chosen for its extremely abundant semen which allows large scale purifications and analyses. The fractions were tested on Balb/c mice spleen cells stimulated with LPS or PHA. The most active fraction was found in the 100-110 kd molecular weight range. The immunosuppressive activity occurred on both B and T cells, but was higher on the former. The active molecule is likely to be a protein. Another fraction of greater than 500 kd MW was also immunosuppressive but its activity disappeared by concentration. It possibly contained aggregates of the 100 kd molecules. The biological role of these immunosuppressive agents could be to protect sperm against female local immune reactions. Similar molecules in human semen might exist and favor the occurrence of acquired immunodeficiency syndrome in male homosexuals.

Animals↗
PubMed1986

Immunofluorescence characterization of Legionella: narrow specificity of polyclonal immunsera to various serogroups and species.

This study was to determine by direct fluorescent antibody staining with antibodies prepared in rabbits, the degree of cross-reactions between serogroups of Legionella pneumophila (1 to 6) and the other antigenic species of Legionella (L. bozemanii, L. dumoffii, and L. micdadei), in order to increase the accuracy of diagnosis and to allow us to reduce the number of conjugates. The polyclonal antibodies were highly species and serogroup-specific without absorption for characterization of Legionella either in patient specimens or in isolated cultures by direct fluorescent antibody staining. No cross-reaction was observed with non-legionella bacteria isolated from sputum specimens. A battery of conjugates for different serogroups and species is necessary for increasing the accuracy of diagnosis of legionellosis.

Animals↗