Antonio Sebastiani

Basophil-bound and serum immunoglobulin E directed against Helicobacter pylori in patients with chronic gastritis.

The immunoglobulin (Ig) E immune response in patients with Helicobacter pylori-associated chronic gastritis has been evaluated. Of 26 patients with H. pylori infection, 22 (84%) tested positive for basophil-bound specific IgE (determined by the histamine release test) and 18 (69%) for serum specific IgE (determined by an enzyme-linked immunosorbent assay). In contrast, only 1 of 17 persons in whom the bacterium was not detected presented cell-bound and serum specific IgE. In the 4 histamine release test--positive but enzyme-linked immunosorbent assay--negative patients, removal of antibody from the basophil surface by acid elution showed that histamine release occurred through an IgE-dependent mechanism. When normal basophils, passively sensitized with serum from IgE-positive patients, were exposed to the H. pylori antigen, a significant release was observed, confirming the class specificity of the response. Inhibition experiments with bacteria other than H. pylori showed that the IgE antibody was specifically directed against this organism. The percentage of antigen-induced histamine release did not correlate with serum specific IgE level. However, the response of basophils to antigenic challenge was proportional to IgE-dependent cellular releasability. This finding suggests that target cell sensitivity may be the most important factor in determining the entity of biological response to the antigenic challenge. The ability of H. pylori to induce a specific IgE immune response could answer key questions regarding the mechanisms inducing gastric inflammation.

Hepatitis C virus infection of salivary gland epithelial cells. Lack of evidence.

BACKGROUND Hepatitis C virus genome (HCV-RNA) has been detected in whole salivary gland tissue of chronically infected patients. However, contamination of the tissue by plasma or blood cells was not excluded by the previous reports. AIMS To assess whether HCV infects the salivary gland epithelial cells in patients with chronic HCV liver disease. METHODS Twenty unselected patients with chronic active hepatitis (11 cases) or active cirrhosis (nine cases) were examined. Serum and saliva samples were obtained from all patients, 12 of whom (seven, chronic active hepatitis; five, active cirrhosis) underwent salivary gland biopsy. PCR for HCV-RNA was performed on RNA extracted from serum, saliva and salivary gland epithelial cells collected by isokinetic gradient separation after trypsin digestion of whole salivary gland tissue. Saliva samples were also examined for the presence of secretory IgA anti-HCV by gel chromatography and ELISA testing. RESULTS HCV-RNA was detected in all sera with titers ranging from 5.42 x 10(5) genome equivalents/ml to 123.2 x 10(5) genome equivalents/ml. Thirteen patients were infected with genotype 1b, four patients had genotype 1a, two patients had genotype 2a and one patient was unclassifiable. Low titer HCV-RNA (<2 x 10(5) genome equivalents/ml) was detected in 3/20 saliva samples (15%) from highly viremic patients infected with 1b genotype. RNA extracted from salivary gland epithelial cells consistently tested negative for HCV-RNA. In addition, all saliva specimens tested negative for secretory-IgA (S-IgA) anti-HCV, even after a 10-fold concentration of the samples. CONCLUSIONS There was no evidence that HCV infects the salivary gland epithelial cells in our viremic patients with HCV chronic liver disease. Low level HCV-RNA in saliva is most probably due to virus spillover from blood.

Histamine release test in the diagnosis of human hydatidosis

An evaluation of the use of the histamine release test (HRT) in the diagnosis of human hydatidosis is presented. This technique, which makes it possible to evaluate directly IgE dependent immediate hypersensitivity by measuring the histamine released from leucocytes (basophils) after antigenic challenge, was compared with the detection of serum specific IgE by the radio‐allergosorbent test (RAST), and with the determination of serum specific IgE by the enzyme‐linked immunosorbent assay (ELISA). Of the 54 patients with hydatidosis, all were positive according to HRT, 42 according to RAST and 47 according to ELISA. No false positive results were obtained by HRT in 43 patients with parasitosis other than hydatidosis, however, of these 43, 10 resulted in false positives according to RAST and five according to ELISA. It is concluded that HRT is more sensitive and more specific than RAST and ELISA.

The prevalence and intensity of intestinal parasites in two Somalian communities

About 85% of the population of two Somali communities harboured soil-transmitted intestinal nematodes and/or protozoa. The commonest parasite (75% in the Lafoole institution and 59% in the Afgoye institution) was Trichuris trichiura. Mixed infections were common. The source of infection is contaminated fields around dwelling quarters, because of indiscriminate defaecation. One of the factors responsible for the higher incidence of hookworm in Lafoole (45%) compared with Afgoye (1.5%) may be the different soil character of the surrounding fields.

Epidemiological study of parasitic infections in Somali nomads

In Somali nomads the incidence of intestinal helminths is very low compared with that observed in Somalian closed institutions and practically no Entamoeba infection occurs. Schistosoma haematobium eggs are observed in urine of 50% of adults nomads. Immunological tests reveal that the relative prevalences of leishmaniasis (the lowest), malaria, and toxoplasmosis (the highest) in nomads are similar to those shown by the same techniques in settled communities.

A new serological technique, time-resolved fluoroimmunoassay (TRFIA), for the immunological diagnosis of urinary schistosomiasis

The application of a new serological method, time-resolved fluoroimmunoassay (TRFIA), is described for the diagnosis of urinary schistosomiasis. A chelate of lanthanides (europium) with a long fluorescent life-time is used as label. The intensity of fluorescence is measured after a delay selected to eliminate almost completely the background fluorescence, which decays rapidly. TRFIA was compared with an established method, enzyme linked immunosorbent assay (ELISA). Using sera from proven cases of Schistosoma haematobium infection, 98.1% of the samples were positive by TRFIA and 86.5% by ELISA. Sera from patients infected with helminths other than schistosomes produced only 1.5% of false positives with TRFIA, compared with 12.3% by ELISA. TRFIA is more sensitive and specific than ELISA.

Hepatitis B virus circulation in three different villages of Somalia

Hepatitis B virus (HBV) circulation was surveyed in three Somalian villages (Buur-Fuul, Mooda-Moode and Bajuni Islands) in different districts and 52 children living in a closed community, aged under one year, were studied. Of the 331 village subjects aged one to 83 years, 12.08% were HBs positive, 29.9% anti-HBs positive, 43.8% anti-HBc positive and 21.4 anti-HBe positive. Among the HBs-positive subjects, 34.7% had HBeAg and 21.7% had anti-HBcAg-IgM. No statistically significant differences were found for HBs, anti-HBs, anti-HBc and anti-HBe among the three villages. HBeAg prevalence was higher in Buur-Fuul than in Mooda-Moode and in Bajuni Islands. HBsAg prevalence was about the same for each age group studied, whereas the prevalence of anti-HBc showed a continuous rise and reached its maximum level of 43.8% in those aged 39 years and older. The proportion of HBs-positive subjects who also carried HBeAg was high in the youngest children but fell with age. HBs-positive children aged under one year had a high anti-HBc-IgM prevalence. Our finding suggests that perinatal infection may play an important role among the Somalian population in determining the reservoir of virus carriers.

High prevalence of anti-hepatitis delta virus antibody in chronic liver disease in Somalia

We have assessed the prevalence of hepatitis delta virus (HDV) infection in people with histologically proven chronic liver disease living in Somalia. Among 104 patients studied (14 with chronic persistent hepatitis, 74 with chronic active hepatitis, and 16 with active cirrhosis), 52 were positive for hepatitis B surface antigen; of these, 26 (50%) carried anti-delta antibodies. HDV infection was detected more frequently in sera from hepatitis B e antigen (HBeAg) negative patients (60.9%) than in HBeAg positive patients (9.1%). Using the dot-blot hybridization technique, serum hepatitis B virus deoxyribonucleic acid was revealed in 73.1% of patients without HDV infection, while it was detected in only 7.7% of anti-delta positive patients. It is concluded that HDV is strongly associated with chronic liver disease in Somalia.

The serological diagnosis of human hydatid disease by time-resolved fluoroimmunoassay

The use of a new immunoassay, time-resolved fluoroimmunoassay (TR-FIA), in the diagnosis of human hydatid disease has been evaluated. This technique, which is based on the labelling of antibodies with europium (Eu), was compared with a well-established method, the enzyme linked immunosorbent assay (ELISA). Of 102 patients with hydatid disease, 97 (95.1%) were positive according to TR-FIA and 83 (81.4%) according to ELISA. The rate of non-specificity for other parasitic infections (n = 206) was 8.7% for TR-FIA and 17.5% for ELISA. It is concluded that TR-FIA is more sensitive and more specific than ELISA in the diagnosis of human hydatid disease.

Reinfection of Somali children with Trichuris trichiura after chemotherapy: relevance of immunostimulation.

The intestinal helminth status of an age-stratified sample (6 to 20 years old) from a Somalian community has been assessed and the typical pattern of highly aggregated parasite distribution found. A reinfection study on a sample of 40 children (treated and untreated with a pentapeptide identical to the active site of the thymic hormone thymopoietin) seemed to indicate that immunological factors play a significant role in modulating the population dynamics of infection in endemic communities.