Rat ileocecal immunocytoma. An ultrastructural study with special attention to the presence of viral particles.

Fifteen spontaneous immunocytomas originating in the ileocecal lymph nodes of Lou/C/Wsl rats were studied by means of electron microscopy. The histology was characteristic, the tumor being formed by an accumulation of large, rounded cells with slightly eccentric ovoid nuclei, large nucleoli, and finely condensed chromatin along the nuclear walls; the cytoplasma was rich in polyribosomes. The appearance of the rough endoplasmic reticulum was apparently the same whether or not the tumor was secretory. Its development varied from one cell to another, and in only a small proportion of cells did it attain any considerable volume. In all the tumors examined, we noted the presence of intracisternal A-particles. In its morphology, the rat immunocytoma resembled the plasmacytomas induced in mice, and it also resembled certain human tumors such as Burkitt's lymphoma.

Conversion from cyclosporine to FK506 for salvage of immunocompromised pediatric liver allografts. Efficacy, toxicity, and dose regimen in 23 children.

Twenty-three pediatric liver transplant recipients (median age 3.9 years) were converted from cyclosporine A-based immunosuppression to FK506 for uncontrollable acute rejection (AR; n = 16), chronic rejection (n = 4), or predominantly nonspecific hepatitis (n = 3). Of these, 19 had received poly- or monoclonal anti-T lymphocyte antibodies either for AR prophylaxis or therapy before FK506 conversion. Full clinical and histologic responses to FK506 therapy were observed in 11/16 cases of AR compared with 0/7 cases of non-AR indications (P = 0.006). Acute FK506 toxicity included renal dysfunction in 12/23 children (52%), neurological disorders in 7/23 (30%), and isolated hyperkalemia in 2/23 (9%), with a poor correlation with the corresponding FK506 trough plasma level. Moreover, a significant impairment of glomerular filtration rate was recorded in the 12 children who received FK506 treatment for more than 6 months (P = 0.002). FK506 therapy had to be definitively withdrawn in 6 cases (fatal infections: n = 4; persistent tremor: n = 1; reason unrelated to FK506: n = 1). Five children developed a lymphoproliferative syndrome (LPS), leading to death in 3 cases despite cessation of the immunosuppressive therapy; in the other 2 patients, LPS was controlled, and the children were successfully retransplanted for chronic rejection under FK506. The occurrence of Epstein-Barr virus primary infection under FK506 therapy was found to constitute a significant risk factor for LPS (P = 0.027). In summary, full response to FK506 conversion was observed in 69% of uncontrollable AR cases; however, 74% and 22% of this probably over-immunosuppressed population experienced major adverse events and LPS under FK506 therapy, respectively.

Immunoassay of hepatitis B surface antigen by particle counting after pepsin digestion.

Particle counting immunoassay is based on latex agglutination, the reaction being measured by instrument counting of the particles remaining unagglutinated. Most interference which generally affects latex agglutination can be avoided by pepsin digestion of the sample, provided the antigen (Ag) of interest resists pepsin, which is the case of the hepatitis B surface antigen (HBsAg). Pepsin treatment has the additional advantage of inactivating antibodies and so releasing the Ag from immune complexes. We have set up an assay of HBsAg, proceeding in a prototype of Impact Instrument (Acade Diagnostic Systems, Belgium) at a rate of 60 samples.h-1 and a total running time of 2 or 4 h. This assay was compared with Abbott radioimmunoassay (RIA) in 706 consecutive patients (A) and 31 selected sera for which values close to the cut-off had been obtained by RIA (B). In A, 38 sera were found positive and 668 negative by both methods. In B, RIA after neutralization classified the samples as positive (n = 14), negative (n = 14), or dubious (n = 3). Complete agreement between latex and RIA was achieved for nine positive, 12 negative, and two dubious samples. Of five RIA-positive samples, two were classified as latex-negative and three as dubious in the latex assay. One sample dubious in RIA was found latex-positive and two RIA-negative samples were found, respectively, latex-positive and dubious; when retested after pepsin digestion, the first of them became RIA-positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Assay of anti-HBs antibodies using a recombinant antigen and latex particle counting: comparison with five commercial tests.

An assay of anti-HBs antibodies based on agglutination of latex particles coated with recombinant HBs-antigen was compared with Abbott radioimmunoassay (Abbott-RIA), which uses a human plasma-derived antigen. The population examined consisted of 76 Abbott-RIA anti-HBs-negative prevaccinated subjects and 1044 serum samples anti-HBs found positive by Abbott-RIA, including 283 samples of subjects vaccinated either with a human plasma-derived vaccine (group A; n = 180) or with a recombinant vaccine (group B; n = 103). Correlation coefficients between the two techniques were respectively r = 0.89 for the whole population (n = 1044), r = 0.98 in group A and r = 0.74 in group B. Anti-HBs titres were higher with latex than with RIA in group B as shown by the regression slopes: latex = 508 + 1.11 RIA in group A and latex = -1138 + 3.97 RIA in group B, suggesting that some vaccinated subjects from group B produced antibodies against epitopes proper to the recombinant antigen. In the prevaccinated population and in group A, the latex results were compared with those of radioimmunoassays (Abbott, Sorin) and enzyme immunoassays (Behring, Roche, Pasteur). Only the Roche-EIA detected anti-HBs in the prevaccinated subjects. The correlation between the various immunoassays was r greater than 0.96 only for values higher than 100 IU/l.

Herpes simplex virus type 2 meningitis without genital lesions: an immunoblot study.

Two sexually active female patients presented with acute meningitis. The CSF abnormalities were severe and persistent. In spite of the absence of genital lesions, serological studies revealed a primary infection by herpes simplex virus type 2. An immunoblot study revealed intrathecal synthesis of anti-herpes antibodies early in the course of the disease.

[Acute maternal anterior poliomyelitis in a non-endemic zone]. / Poliomyélite antérieure aiguë maternelle en zone non endémique.

The authors report the case of a 26 year old woman with acute anterior poliomyelitis contracted during the vaccination of her baby. Despite having been herself vaccinated in infancy she was not protected against the poliovirus. The clinical interest of this uncommon case is a severe paralytic state with definitive paraplegia. The authors suggest serologic testing of patients born before 1967 especially if they are at risk of encountering the virus.

[Cytomegalovirus and pregnancy. Fetal and neonatal risk]. / Cytomégalovirus et grossesse. Risque foetal et néonatal.

A review of the literature shows that 36% of pregnant women are not immunized against cytomegalovirus; 2.11% of these patients will have a primary infection during their pregnancy. The fetal transmission rate is 30%. Viruria after delivery is the unique proven sign of infection; but is only present in 4 to 5 infants per 1,000 births. Of those, 17% will be symptomatic at delivery and 10% will develop sequels as late as seven years later. CMV can be reactivated during pregnancy. These cases are less dangerous but the fetal risk is always present.

[Rapid detection of viruses by electron microscopy. Interest of negative staining for the diagnosis of some skin lesions of viral origin (author's transl)]. / Détection rapide des virus au microscope électronique. Intérêt de la méthode de coloration négative pour le diagnostic de certaines dermatoses d'origine virale.

Viral particles can be visualized by electron microscopy using negative staining. Such an approach, widely used in research, provides a method for detecting virions which are present in clinical specimens. It is considered to be the method of choice in cases with suspicion of smallpox. Direct visualization has been systematically applied for the diagnosis of viral diseases in dermatology. Negative staining by pseudoreplication appears to be simple, rapid and efficient. It was thus possible to detect viruses in vesicle fluids, in scrapings and in crusts. During the course of this study 66 cases have been analyzed and viruses have been demonstrated in 49. If a skin lesion seems to be of viral origin, direct examination may confirm the clinical impression.

Requirements for diagnosis of prenatal cytomegalovirus infection by amniotic fluid culture.

BACKGROUND: Amniotic fluid culture is considered to be the best method for the detection of antenatal cytomegalovirus (CMV) infection and prediction of congenital CMV infection. Recently, however, some false-negative results have been reported. OBJECTIVES: Prediction of congenital CMV infection by amniotic fluid culture with emphasis on false-negative results. STUDY DESIGN: Retrospective study of 42 pregnant women with primary CMV infection. First, estimation of seroconversion related to the gestational age was established. Afterwards, results of amniotic fluid culture were compared either with CMV isolation from biopsies from aborted fetuses, or with viral culture of newborns' urine. RESULTS: In 18 cases (43%), amniotic fluid culture gave negative results which coincided with 18 uninfected newborns. In 18 other cases (43%), amniotic fluid culture was positive for CMV: 7 newborns with CMV viruria and 11 terminations of pregnancy with CMV isolated from fetal biopsies. In the remaining 6 cases, amniotic fluid culture gave negative results, whereas the 6 newborns were all infected. CONCLUSION: Amniotic fluid culture remains an accurate method for the diagnosis of CMV antenatal infection. However, in order to avoid false-negative results, the importance of a correct estimation of the gestational age of seroconversion and of a sufficient interval between primary infection and amniocentesis are stressed.

Poliovirus antibodies in age groups: an assessment of obligatory vaccination in Belgium.

Since 1967, compulsory oral vaccination before 2 years of age has been nearly the only form of poliovaccination practiced in Belgium, and there have been almost no cases of polio. In recent sera from 2,225 Belgians, 2 year olds lacked demonstrable seroneutralizing antibody, in 31% for type 1, in 8% for type 2, and in 21% for type 3. The lack of antibodies grew as the children reached 11--12 years, at which age 65% lacked antibody for type 1, 15% for type 2, and 54% for type 3; only 19% had antibodies against all types. It is argued that this decline of antibodies is not due to insufficient vaccination in former years, but is a strong example of the waning of vaccine-acquired serum antibody. Antibody rates went up after age 12. The highest rates of types 1 and 3 antibodies were seen at age 20--59. There was some decrease of antibody after 60 years. Mean antibody titers paralleled positivity rates. Results of two laboratories studying different populations with different standard techniques were similar. The data support revaccination at school entrance.

Epstein-barr Virus (EBV) intracellular antigens: factors affecting the patterns of immunofluorescence.

Immunofluorescent pictures of Epstein-Barr Virus (EBV) antigens were studied with regard to the lability of the antigens to heat and to solvents as well as to the modifications of the immunofluorescent patterns related to the length of drying time of the cell smears. The nuclear antigen (EBNA) and the early restricted antigen (EA-R) appeared to be sensitive to heating 30 minutes at 56 degrees C. Lengthening of the drying time of the cell smears results in a progressive dispersion of three antigens; viral capsid antigen (VCA), early diffuse antigen (EA-D) and EA-R in the cell and in some apparent loss of EBNA. Petroleum benzine which can be used as a fixative on plastic, support, allows the detection of all four antigens.

Early diagnosis of CMV infection by detection of pp65 antigen in 91 renal transplant recipients.

We evaluated how accurately a CMU antigenemia test correlated with classical CMU infection markers. We studied 91 kidney transplant recipients from February 1991 to June 1992. Antigenemia (pp65 antigen) was positive in 100% of cases of primary infection and in 70% of cases of reactivation and/or reinfection. Furthermore, antigenemia detected more infections (71%) than viremia (16%). The antigenemia test proved to be highly specific: it remained consistently negative in 22 seronegative patients, as well as in 19 of 20 seropositive recipients without recurrent infection. pp65 Antigen in the polymorphonuclear leukocytes was detected earlier than, or simultaneously with, virus culture in 78% of cases and became positive before serologic tests of primary and secondary infection in nearly 90% of cases. Most importantly, the antigenemia test detected all of the symptomatic cases.

Specific IgE detected by ELISA and immunoblot after human cytomegalovirus infection (HCMV) in renal transplant (RT) recipients.

BACKGROUND: Specific HCMV IgE response has been reported by some authors, and was proposed as a valuable virologic marker of CMV infection. OBJECTIVES: we evaluated specific HCMV IgE in renal transplant patients with active (primary and secondary) HCMV infection with special interest to symptomatic infections. STUDY DESIGN: Specific IgE was tested retrospectively by ELISA and immunoblot (IB) on sera of 55 RT patients who were followed before and after transplantation with virologic markers of CMV infection. RESULTS: Total serum IgE levels were similar in control group and in patients with primary and secondary HCMV infections. Anti-CMV specific IgE response by ELISA was more frequently found in patients with primary infection (76.9%) than in patients with secondary infection (47.1%). These specific IgE reacted on immunoblot with a 150 kDa protein in 84.6% of patients with primary infection and 94.1% with secondary infections; and reacted with rp52 (pUL44) in 76.9% of primary infection and 47.1% of secondary infection. CONCLUSIONS: Anti-CMV specific IgE tested by immunoblot and ELISA is a marker of CMV infection. It was clearly detected in cases of active infection (primary and secondary) and was present in cases with severe CMV clinical manifestations. In contrast, anti-CMV specific IgE, was consistently negative among healthy blood donors. This is the first report of CMV proteins detected by IgE immunoblot.

Epstein-Barr virus early antigen titer by immunofluorescence in microplates. A new semi-automated method based on microtiter system.

For the titration of antibodies directed against Epstein-Barr Virus early antigen (EBV-EA) we describe a method in microplates with the Microtiter System (Cooke Engineering Co., Alexandria, Va). Using this technique, which allows rapid epidemiological investigations, we have titered anti-EBV-EA antibodies in different groups of patients and controls, and particularly in group which had recent contact with infectious mononucleosis. In this group the percentage of individuals having antibodies directed against the EBV-EA antigen was significantly higher than in the group of controls.

Epstein-Barr virus viral capsid antigen titer by immunofluorescence with microplates: new semiautomated method based on the microtiter system.

A semiautomated method of an indirect immunofluorescence technique for the titration of antibodies directed against viral capsid antigens of Epstein-Barr virus has been developed with Microtiter system units. By this method, a technician is able to titrate some hundred samples daily. The technique is safe, easy, and reproducible. The various procedures are described, and the sensitivity of the test is discussed.