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Biomedical subjects

J Pillot

Publications and source records attributed to J Pillot.

At least 91 records · Page 5Linked to original sources
PubMed1990

Human seminal plasma suppresses the chemiluminescence of polymorphonuclears without modifying phagocytosis.

The suppressive activity of human seminal plasma was confirmed on the luminol-amplified chemiluminescent reaction of human polymorphonuclears. This suppression was found to be dose-dependent and noncytotoxic. The responsible factor appeared to be a radical scavenger of low molecular weight, acting selectively on hydrogen peroxide. Correlation with glandular markers of semen indicated this molecule to have a prostatic origin. Neither crude seminal plasma nor this factor were found to suppress intracellular engulfment and killing of bacteria. This molecule seems to cooperate with the other semen antioxidants to protect sperm cells from extracellular oxygen radicals.

Humans↗
PubMed1990

[Primates in the study of hepatitis viruses].

There is no a conventional tissue culture system for the propagation of the hepatitis viruses and only some of them can be maintain in continuous cell culture in particular conditions. A transmissibility of hepatitis is limited to primates. The narrow host specificity may help to establish the classification of the hepatitis viruses and their mode of transmission. Moreover, the primate animal model provided the most accessible source of viruses and for clinical reasons presents the only opportunity for the studies of pathogenic mechanisms involving cellular immunity with allogenic restriction. The marmosets and chimpanzees susceptible to the hepatitis A and B viruses, respectively are the primates of choice for the experimental models. For the studies on parenterally transmitted NANB hepatitis the chimpanzee and some rhesus monkeys may provide an animal system. At last, most of the primates seem to be susceptible to agent responsible for the water-borne non A non B hepatitis.

Animals↗
PubMed1990

[Prevalence of hepatitis B virus in women of childbearing age in Mali].

A serological investigation on adult female in Mali show a high degree of positivity of hepatitis B virus (HBV) markers, of which 42% HBs Ag +. Only 6% exhibit active replication. The low prevalence of anti-HBs (+) with a high degree of anti-HB (+) explain a high incidence of infection with a low immune response to HBs antigen. The existence of anti-Delta (+) asymptomatic carriers is an additional support to a vaccination programme.

Adolescent↗
PubMed1989

HLA linked immune response to S and pre-S2 gene products in hepatitis B vaccination.

In order to detect a possible HLA linked genetic control of human immune responses to hepatitis B virus, forty healthy adult persons of the same age typed for HLA-A, -B and -DR antigens, were vaccinated against virus hepatitis B and sequentially tested for anti-HBs and anti-pre-S2 antibodies. They received three injections of Hevac-B Pasteur vaccine, the second 1 month and the third 3 months after the first. Following the third immunization, 38 individuals (95%) had a protective level of anti-HBs antibodies and 17 (42.3%) had a positive level of anti-pre-S2 antibodies. HLA-A11 antigen was significantly more frequent (pc = 0.007) among anti-HBs high responders than low responders. In addition, anti-HBs high responders were more frequently HLA-DR1, and less frequently HLA-DR4 and DR7 positive; corrected values, however, were not significant. Anti-pre-S2 high responders showed an apparent increase of HLA-B7, B14 or DR3 antigens, when compared to low responders (pc not significant).

Adult↗
PubMed1988

Prognostic value of HBsAg/IgM complexes in hepatitis B patients: nature of the proteins involved.

Hepatitis B surface antigen (HBsAg)/IgM complexes were measured using a solid phase radioimmunoassay in sera of patients with acute or chronic hepatitis B. These complexes were found in 6 out of 18 patients four weeks after the onset of the disease and only one of them developed chronic hepatitis. HBsAg/IgM complexes correlated with HBsAg, hepatitis B e antigen (HBeAg), and pre-S2 concentration. The precipitation of HBsAg/IgM reactivity by polyethylene-glycol (PEG) and the binding of this activity to the surface of certain uncoated enzyme linked immunosorbent assay (ELISA) plates indicates that HBsAg/IgM positivity may reflect the presence of circulating complexes in serum. HBsAg and pre-S2 were found as components of the complexes but anti-HBs, anti-pre-S2, and polymerized human serum albumin (pHSA) were not. An immune binding between HBsAg and IgM is still questionable. Whatever the nature of the HBsAg/IgM complexes, their detection does not seem to be an earlier indicator of prognosis than HBeAg and/or pre-S2.

Adult↗
PubMed1988

Occurrence of pre-S1 antigen in viremic and nonviremic carriers of hepatitis B surface antigen.

The proteins of viral envelope, encoded by the pre-S1 region of HBV-DNA, were measured quantitatively with enzyme immunoassay using monoclonal antibodies directed to pre-S1 epitope and correlated with the expression of pre-S2 region encoded epitope and other HBV markers. In acute HBV infection, both pre-S encoded proteins were detected in sera along with markers of viral replication and disappeared shortly before complete virus clearance while high HBsAg titers were still present. Pre-S1 antigen was present in most (95.5%) symptomatic and asymptomatic chronic HBsAg carriers. There was no correlation between the presence of pre-S1 and HBeAg or HBV-DNA in serum: 73% of sera with pre-S1 determinants were anti-HBe positive, and only 25.4% were positive for HBV-DNA. Most pre-S1 activity in sera of viremic carriers was detected in fractions of sucrose gradient containing subviral 22-nm particles, and much less in those containing infectious virions. In asymptomatic, nonviremic HBsAg carriers, pre-S1 was located only on subviral 22-nm forms. Pre-S1 positive particles had no accessible pre-S2 epitope, which is recognized specifically by monoclonal anti-pre-S2 (F124) antibody. These results show that the synthesis of the large protein of HBV envelope may occur also in the absence of active viral replication, and in these cases pre-S1 encoded sequences are on subviral particles of HBsAg. Therefore, pre-S1 is not a serologic marker of infectious virus. Disappearance of pre-S1 epitopes on HBsAg occurs only before complete clearance of the virus, and this may have potential prognostic relevance.

Acute Disease↗
PubMed1988

Prenatal and postnatal production of IgM and IgA antibodies to rubella virus studied by antibody capture immunoassay.

Rubella virus-specific IgM and IgA antibodies were quantitated by antibody capture immunoassay in adults after primary infection and after experimentally induced reinfection. Antibodies to rubella virus were also detected in fetuses whose mothers had rubella before week 18 of pregnancy. IgM and IgA concentrations in fetal blood were determined by radial immunodiffusion and enzyme immunoassay, respectively. In primary postnatal infection, IgM antibodies were consistently found until week 8 after onset of the disease, and after week 14 these antibodies were usually no longer detected. The time of disappearance of rubella virus-specific IgA varied with each individual. After vaccination of previously immune volunteers, no change was noted in level of IgA antibody, and no IgM antibody was detected. In infected fetuses, total IgM and IgA concentrations rose significantly, and rubella virus-specific IgM and IgA antibodies were detected as early as week 22 of pregnancy.

Antibodies, Viral↗
PubMed1988

Delineation between T- and B-suppressive molecules from human seminal plasma: I. Partial characterization of a 180-kD protein inhibiting the B response to T-independent antigens.

The immunosuppressive activity of fractionated human seminal plasma (SP) was investigated both in vitro (on human lymphocytes) and in vivo with Balb/c mice. SP fractionation by dialysis allowed delineation of the major suppressor factors according to their respective sizes--small (less than 12 kD) or large (greater than 12 kD). In vitro, large molecules were found to suppress the B-cell proliferative response induced by the Nocardia mitogen, while small molecules suppressed the T-cell proliferation induced by phytohemagglutinin. In vivo, immunosuppression was obtained almost exclusively on T-independent responses after preliminary treatments either with unfractionated SP or with large SP molecules. Both type 1 and type 2 T-independent responses were suppressed, as evidenced by plaque-forming cells and antibody assays. In contrast, no immunosuppression was found in vivo after treatment by small SP molecules. Purification of the B-cell suppressor by gel filtration and high-performance liquid chromatography, as well as by preparative isofocusing, indicated that its molecular weight was 180 kD and its isoelectric charge was between pH 5 and 6. This factor is a protein, as evidenced by pronase digestion. A possible role for this molecule in the protection of sperm against the female immune system is discussed.

Animals↗
PubMed1988

[Trial of hepatitis B prophylaxis in children born to mothers carrying HBs antigen in New Caledonia].

A prophylaxis trial of hepatitis B at birth was carried out in New Caledonia. Ninety-nine newborns from women carrying hepatitis B antigen during pregnancy were immunized. The prophylaxis protocol was as follows: anti-HBs immunoglobulin and the first dose of vaccine at birth if the mother was HBe Ag+ or HBe Ag- without anti-HBe, only vaccination if the mother showed anti-HBe antibodies. 73.8% had anti-HBs antibodies when checked at 6 months; at the age of one year, this figure was 60.4%. Four months after the booster injection, 68.3% were anti-HBs positive. Among all these children, three of them were born to HBe Ag+ mothers became HBs Ag/HBe Ag positive. The control group studied showed that mother-infant vertical transmission was not the only route of contamination in children in New Caledonia.

Female↗
PubMed1987

Detection of antibodies to pre-S2 encoded epitopes of hepatitis B virus by monoclonal antibody-enzyme immunoassay.

An inhibition enzyme immunoassay (IEIA) for the detection of anti-pre-S2 antibody has been developed and used to evaluate anti-pre-S2 responses in the sera of patients recovering from acute type B hepatitis and in the sera of healthy recipients of HBV vaccine. In the assay, we used two monoclonal antibodies recognizing the nonoverlapping epitopes (pre-S2a and pre-S2b) of the pre-S2 protein of HBV envelope which compete with human anti-pre-S2 for the limited antibody-binding sites on recombinant HBsAg particles (pre-S and S gene product). Two variants of the method were assayed employing the reference pre-S2 antigen on the solid (IEIA-sp) or in the liquid phase (IEIA-lp). Two McAbs were used to detect antibodies reacting specifically with pre-S2a and pre-S2b epitopes of the pre-S2 sequence. Both variants gave similar results and were successfully used for the determination of anti-pre-s2 in sera. We demonstrated that during HBV infection as well as after vaccination against HBV both pre-S2 epitopes generate specific immune responses. Anti-pre-S2 were detected in 45.3% patients recovering from HBV infection and in 43.7% of healthy recipients of the HBV vaccine licensed in France. Anti-pre-S2a and anti-pre-S2b were detected in sera in dilutions up to 10(-5). IEIA may provide a specific and highly sensitive screening test for monitoring serum anti-pre-S2 levels during HBV infection and after immunization with HBV vaccine.

Antibodies, Monoclonal↗
PubMed1987

A monoclonal antibody enzyme immunoassay for the detection of epitopes encoded by the pre-S2 region of the hepatitis B virus genome.

Pre-S2-coded sequences of the hepatitis B virus (HBV) represent important serological markers of HBV infection and elicit the antibodies essential for recovery from type B hepatitis. Monoclonal antibodies (McAbs) directed against two non-overlapping epitopes (pre-S2a and pre-S2b) of the pre-S2 protein of HBV were used to develop an enzyme immunosorbent assay (EIA). The assay was based on the solid-phase sandwich principle in which two different epitope-specific antibodies were used as immunadsorbents and as enzyme-labelled probes. The assay sensitivity was in the pg range and permitted precise quantitation of the pre-S2 sequences in sera. Using the 'site-specific' monoclonal assay we demonstrated that pre-S2a and pre-S2b epitopes are expressed on HBsAg particles of both ay and ad subtypes. The assay is the most sensitive currently available method for the detection of pre-S2 epitopes and may be used for routine immunodiagnosis of hepatitis B.

Antibodies, Monoclonal↗