[The isolated presence of anti-HBc antibodies: prevalence and interpretation based on the results of viral DNA research and anti-HBs antibodies measurement after vaccination]. / Présence isolée de l'anticorps anti-HBc: prévalence et interprétation à l'aide des résultats de recherche d l'ADN viral et du dosage des anticorps anti-HBs après vaccination.

In order to study the significance of the isolated presence of anti-HBc antibodies, we have looked for the 3 classic serological markers of the hepatitis B (HBs antigen, anti-HBs and anti-HBc antibodies) in 1,586 hospital agents who are to vaccinate in the framework of a campaign of systematic vaccination of the hospital personnel of university hospitals of Sfax for a period of 18 months. We identified subjects who presented isolated anti-HBc antibodies (33 individuals = 2.08%). In these subjects'serum, we performed a research of the DNA of hepatitis B virus (HBV) with a PCR hybridization technique using a couple of primers. One week after administration of a vaccine dose, we also measured anti-HBs antibodies in their sera. Among the tested 18 personnel with anti-HBc isolated antibodies, 11.1% had low rates of anti-HBs antibodies indicating that there is presumably primary antibody response and therefore a false positivity of anti-HBc antibodies in pre-vaccinal serology; while 11.1% others had higher rates of anti-HBs antibodies corresponding to a secondary antibody response, which witness a previous HBV immunisation. The research of the HBV-DNA was positive in 11.1% of tested personnel, testifying a presumably chronic portage of the virus with low rates of the HBs antigen undetectable with the serological techniques. For the remainder subjects with isolated anti-HBc antibodies (66.7%), the interpretation remains ambiguous.

[Presence of cryoprecipitates in the serum of patients with rheumatoid arthritis]. / Présence de cryoprécipités dans le sérum de malades atteints de polyarthrite rhumatoïde

Serum samples from 140 controls (C) and from 72 patients suffering from defined rheumatoid polyarthritis (RP) were tested for cryoglobulins (CG). CG were found in 19.7 percent of C and 55 percent of RP : a highly significant difference (p less than or equal to 0.001). In the controls there was no correlation between the CG and age or sex. The RP with cryoglobulins seemed to have more inflammation, but systemic manifestations were not any more frequent than in the cryonegative RP. In the RP a correlation was noted between the presence of CG and the following parameters : increase in the sedimentation rate, rise in serum immunoglobulins, IgA and IgC, presence of antinuclear factors, and drop in the C4 fraction of complement. There was no correlation with the presence of the rheumatoid factor in the serum. In 33 cryoprecipitates in the RP, 7 contained IgG, 1 IgM, 22 IgM-IgG -- of which 11 contained C1q and 16 rheumatoid factor -- and 3 contained IgA-IgM-IgG -- of which 1 contained C1q and 2 rheumatoid factor. Some of the biochemical data support the hypothesis that likens these cryoglobulins to immune complexes.

[Circulating immune complexes in man; precipitation of immune complexes with polyethylene glycol and their characterization by Clq bound to immunoglobulins]. / Mise en évidence d'immuncomplexes circulants chez l'homme; précipitation des immuncomplexes par le polyéthylène glycol et leur caractérisation par le Clq lié aux immunoglobulines

Use of an experimental model consisting of purified tetanal toxoid and sera of patients vaccinated with this antigen reveals that immunodiffusion characterisation of C1q bound to immune complexes (IC) precipitating with 2,5% PEG (6000) represents a very sensitive means of detection of such IC. The majority of sera of patients with disorders in which IC can be suspected gives positive reactions. Precipitates contain IgG and IgM bound to C1q and rheumatoid factor is constantly detected. The reaction is positive among 10% of healthy patients: the possibility of circulating IC free from any pathological cases is under study.

The problem of purification of HBs antigen.

Purification techniques utilized until now do not allow to obtain an HBs antigen totally free from one or more protein constituents of the serum. The authors describe the method which has given the best results; this method combines the utilization of silicate, Sephadex G200 and ultracentrifugation. The authors then determined the nature of the relations between HbsAg and the serum proteins. They have perfected a screening technique allowing to detect the immune complexes by means of a tetanus antigen-tetanus antitoxin model. Sixty-nine patients with viral hepatitis A and B were tested. It was observed that the immune complexes are in relation with the IgM which are themselves correlated with the rheumatoid factor: the mu chains found in purified HBsAg could correspond to the rheumatoid factor reacting with the Fc of IgG bound to HBsAg.

[Serodiagnosis of human brucellosis]. / Sérodiagnostic de la brucellose humaine

On the basis of the serological study of 1000 sera obtained from patients suspected of suffering from brucellosis, the authors emphasis the theoretical data which confer upon this complement fixation reaction a greater reliability than the agglutination reaction. Using an appropriate antigenic preparation, the complement fixation reaction indeed proves to be of greater interest than the classical Wright sero-agglutination test in the diagnosis of brucellosis.