Hiding in the yolk: A unique feature of Legionella pneumophila infection of zebrafish

The zebrafish has become a powerful model organism to study host-pathogen interactions. Here, we developed a zebrafish model to dissect the innate immune response to Legionella pneumophila during infection. We show that L. pneumophila cause zebrafish larvae death in a dose dependent manner. Additionally, we show that macrophages are the first line of defence and cooperate with neutrophils to clear the infection. Immunocompromised humans have an increased propensity to develop pneumonia, when either macrophages or neutrophils are depleted, these "immunocompromised" larvae become lethally sensitive to L. pneumophila. Also, as observed in human infections, the adaptor signalling molecule Myd88 is not required to control disease in the larvae. Furthermore, proinflammatory cytokine genes il1β and tnf-α were upregulated during infection, recapitulating key immune responses seen in human infection. Strikingly, we uncovered a previously undescribed infection phenotype in zebrafish larvae, whereby bloodborne, wild type L. pneumophila invade and grow in the larval yolk region, a phenotype not observed with a type IV secretion system deficient mutant that cannot translocate effectors into its host cell. Thus, zebrafish larva represents an innovative L. pneumophila infection model that mimics important aspects of the human immune response to L. pneumophila infection and will allow the elucidation of mechanisms by which type IV secretion effectors allow L. pneumophila to cross host cell membranes and obtain nutrients from nutrient rich environments.

CSF-contacting neurons respond to Streptococcus pneumoniae and promote host survival during central nervous system infection

The pathogenic bacterium Streptococcus pneumoniae (S. pneumoniae) can invade the cerebrospinal fluid (CSF) and cause meningitis with devastating consequences. Whether and how sensory cells in the central nervous system (CNS) become activated during bacterial infection, as recently reported for the peripheral nervous system, is not known. We find that CSF infection by S. pneumoniae in larval zebrafish leads to changes in posture and behavior that are reminiscent of pneumococcal meningitis, including dorsal arching and epileptic-like seizures. We show that during infection, invasion of the CSF by S. pneumoniae massively activates in vivo sensory neurons contacting the CSF, referred to as "CSF-cNs" and previously shown to detect spinal curvature and to control posture, locomotion, and spine morphogenesis. We find that CSF-cNs express orphan bitter taste receptors and respond in vitro to bacterial supernatant and metabolites via massive calcium transients, similar to the ones observed in vivo during infection. Upon infection, CSF-cNs also upregulate the expression of numerous cytokines and complement components involved in innate immunity. Accordingly, we demonstrate, using cell-specific ablation and blockade of neurotransmission, that CSF-cN neurosecretion enhances survival of the host during S. pneumoniae infection. Finally, we show that CSF-cNs respond to various pathogenic bacteria causing meningitis in humans, as well as to the supernatant of cells infected by a neurotropic virus. Altogether, our work uncovers that central sensory neurons in the spinal cord, previously involved in postural control and morphogenesis, contribute as well to host survival by responding to the invasion of the CSF by pathogenic bacteria during meningitis.

Latest trends in bioimaging and building a proactive network of early-career young scientists around bioimaging in Europe

Biological research is in constant need of new methodological developments to assess organization and functions at various scales ranging from whole organisms to interactions between proteins. One of the main ways to evidence and quantify biological phenomena is imaging. Fluorescence microscopy and label-free microscopy are in particular highly active fields of research due to their compatibility with living samples as well as their versatility. The Imabio Young Scientists Network (YSN) is a group of young scientists (PhD students, postdocs and engineers) who are excited about bioimaging and aim to create a proactive network of researchers with the same interest. YSN is endorsed by the bioimaging network GDR Imabio in France, where the initiative was started in 2019. Since then, we aim to organize the Imabio YSN conference every year to expand the network to other European countries, establish new collaborations and ignite new scientific ideas. From 6-8 July 2022, the YSN including researchers from the domains of life sciences, chemistry, physics and computational sciences met at the Third Imabio YSN Conference 2022 in Lyon to discuss the latest bioimaging technologies and biological discoveries. In this Meeting Review, we describe the essence of the scientific debates, highlight remarkable talks, and focus on the Career Development session, which is unique to the YSN conference, providing a career perspective to young scientists and help to answer all their questions at this career stage. This conference was a truly interdisciplinary reunion of scientists who are eager to push the frontiers of bioimaging in order to understand the complexity of biological systems.

Exploring Zebrafish Larvae as a COVID-19 Model: Probable Abortive SARS-CoV-2 Replication in the Swim Bladder

Animal models are essential to understanding COVID-19 pathophysiology and for preclinical assessment of drugs and other therapeutic or prophylactic interventions. We explored the small, cheap, and transparent zebrafish larva as a potential host for SARS-CoV-2. Bath exposure, as well as microinjection in the coelom, pericardium, brain ventricle, or bloodstream, resulted in a rapid decrease of SARS-CoV-2 RNA in wild-type larvae. However, when the virus was inoculated in the swim bladder, viral RNA stabilized after 24 h. By immunohistochemistry, epithelial cells containing SARS-CoV-2 nucleoprotein were observed in the swim bladder wall. Our data suggest an abortive infection of the swim bladder. In some animals, several variants of concern were also tested with no evidence of increased infectivity in our model. Low infectivity of SARS-CoV-2 in zebrafish larvae was not due to the host type I interferon response, as comparable viral loads were detected in type I interferon-deficient animals. A mosaic overexpression of human ACE2 was not sufficient to increase SARS-CoV-2 infectivity in zebrafish embryos or in fish cells in vitro. In conclusion, wild-type zebrafish larvae appear mostly non-permissive to SARS-CoV-2, except in the swim bladder, an aerial organ sharing similarities with the mammalian lung.

Exploring Zebrafish Larvae as a COVID-19 Model: Probable Abortive SARS-CoV-2 Replication in the Swim Bladder

Animal models are essential to understanding COVID-19 pathophysiology and for preclinical assessment of drugs and other therapeutic or prophylactic interventions. We explored the small, cheap, and transparent zebrafish larva as a potential host for SARS-CoV-2. Bath exposure, as well as microinjection in the coelom, pericardium, brain ventricle, or bloodstream, resulted in a rapid decrease of SARS-CoV-2 RNA in wild-type larvae. However, when the virus was inoculated in the swim bladder, viral RNA stabilized after 24 h. By immunohistochemistry, epithelial cells containing SARS-CoV-2 nucleoprotein were observed in the swim bladder wall. Our data suggest an abortive infection of the swim bladder. In some animals, several variants of concern were also tested with no evidence of increased infectivity in our model. Low infectivity of SARS-CoV-2 in zebrafish larvae was not due to the host type I interferon response, as comparable viral loads were detected in type I interferon-deficient animals. A mosaic overexpression of human ACE2 was not sufficient to increase SARS-CoV-2 infectivity in zebrafish embryos or in fish cells in vitro. In conclusion, wild-type zebrafish larvae appear mostly non-permissive to SARS-CoV-2, except in the swim bladder, an aerial organ sharing similarities with the mammalian lung.

Long-term liver histology improvement in patients with chronic hepatitis C and sustained response to interferon

A retrospective multicentre survey was conducted to evaluate, in patients with chronic hepatitis C, the long-term liver histological changes induced by interferon (IFN). A total of 112 patients (mean age 46.4 years) were studied. All patients had received a 6-12-month IFN-alpha course (6-18 MU/week) and had successively undergone clinical, biochemical and virological follow-up for at least 36 months (range: 36-76). In each patient, two liver biopsies had been performed: 1-6 months before treatment and, 12-76 months after its completion. In 87 patients with biochemical and virological sustained response persisting for 12 months after therapy, post-treatment liver necroinflammation and fibrosis mean(+/-SD) scores (Knodell index) were significantly lower than pretreatment scores (2.9 +/- 2.2 vs 6.8 +/- 2.9 and 0.8 +/- 1.0 vs 1.2 +/- 1.1, respectively; P < 0.01). In 25 patients who relapsed within 1 year, necroinflammation and fibrosis post-treatment mean scores were similar to pretreatment scores (7.4 +/- 3.2 vs 6.9 +/- 3.1 and 1.8 +/- 1.3 vs 1.6 +/- 1.2, respectively; P > 0.05). On an individual basis, necroinflammation decreased in 87% of sustained responders but only in 36% of relapsers (P < 0.001), whereas fibrosis decreased in 44% of sustained responders but only in 14% of relapsers (P < 0.001). In sustained responders with biopsies performed 12-23 months (n=34), 24-35 months (n=26) or more than 36 months (n=27) after treatment, a progressive decrease of mean necroinflammatory score was observed (-2.6 +/- 2.1, -4.1 +/- 3.4 and -5.2 +/- 3.7 points, respectively; P < 0.01). A similar pattern was observed in fibrosis score (-0.3 +/- 0.6, -0.3 +/- 0.7 and -0.7 +/- 0.9 points, respectively; P < 0.05). Hence, among chronic hepatitis C patients treated with IFN, those with a 12-month sustained response, unlike those who relapse, have a long-term progressive reduction and, in some cases, a complete regression of liver histological damage.

Doppler sonography measurement of portal blood flow velocity after glucagon injection in patients with chronic HCV infection

Doppler sonography measurement of portal flow velocity (PFV) after glucagon injection was performed in 45 patients with chronic hepatitis C virus (HCV) infection. Patients were divided into three groups: group 1 = no or mild liver fibrosis; group 2 = moderate to severe liver fibrosis, and group 3 = liver cirrhosis. All patients were examined using a Doppler ultrasound (US) multipurpose equipment and a convex 3.5-MHz probe, 10 min before (baseline), as well as 5 and 10 min after, IV administration of 1 mg of glucagon chloride. No significant differences were found in mean baseline PFV among group 1 (19.4 +/- 2.4 cm/s), group 2 (20.1 +/- 3.6 cm/s) and group 3 (17.5 +/- 3.7 cm/s). Five minutes after glucagon injection, all three groups showed significantly increased values of mean PFV (25.6 +/- 4.8, 23.7 +/- 4.0 and 19.5 +/- 5.0 cm/s, respectively; p < 0.05 vs. baseline). The mean increase of PFV above baseline was significantly higher in group 1 (7.9 +/- 3.7 cm/s) than in group 2 (4.5 +/- 3.9 cm/s) (p < 0.05) or in group 3 (2.7 +/- 2.3 cm/s) (p < 0.05). A significant inverse correlation was found between individual values of fibrosis score and of individual increase of PFV. In patients with chronic HCV infection, Doppler sonography measurement of PFV after glucagon injection could be useful in assessing the severity of liver histological damage.

Leukocyte and platelet lowering by some interferon types during viral hepatitis treatment

BACKGROUND/AIMS

The hematologic toxicity (leukothrombocytopenia) of interferon therapy is well known and frequently observed; it may vary, however, according to the type of interferon administered.

METHODOLOGY

We retrospectively assessed 158 patients with chronic viral hepatitis treated for 6-12 months with alpha (recombinant, lymphoblastoid or leukocyte) or beta interferon to monitor leukothrombocytopenia.

RESULTS

During treatment, a significant decrease in leukocyte and platelet counts was detected in 48% and 43% of patients, respectively. The maximum decrease (31% and 26% of pre-treatment values; p<0.01) occurred after 4.9 and 4.2 months of treatment. No patient showed clinical symptoms of leukopenia or thrombocytopenia. Beta-interferon yielded the smallest decreases in leukocyte and platelet counts (-21% and -16% of pre-treatment values, respectively). Among alpha interferons, the lymphoblastoid (9 MU/week) produced the largest decrease both in leukocyte (38%; p<0.05 vs any other type) and in platelet (32%) number. The same dose of leukocyte interferon had the smallest effect (leukocytes: -27%; platelets: -2%), while recombinant interferon showed intermediate toxicity (-32% and -26% respectively).

CONCLUSIONS

From this retrospective study, the hematologic toxicity of alpha and alpha interferons usually emerges as mild. However, leukopenia and thrombocytopenia may be induced more frequently by some of these interferon types.

[Glucagon test for Doppler sonography measurement of portal flow in chronic HCV infections]

Purpose - To evaluate whether Doppler sonography measurement of portal flow velocity (PFV) after glucagon injection can be useful in assessing the severity of liver damage in chronic HCV infection. Methods - Forty-five patients (32 males and 13 females; mean age 54.1 14.8 years) with biochemical (raised serum ALT levels), virological (positive serum HCV RNA test) and histological (liver biopsy) evidence of chronic HCV infection were included in the study. According to hepatitis staging (degree of liver fibrosis), as assessed by Knodell histological activity index, patients were divided into three groups: group 1 (n.=17), with no or mild fibrosis (fibrosis score: 0-1); group 2 (n.=11), with severe fibrosis (score: 3); and group 3 (n.=17), with liver cirrhosis (score: 4). For sonographic measurements of PFV, a Doppler ultrasound multi-purpose equipment and a convex 3.5 MHz probe were used. All patients were examined after an 8-hour fast, in supine position, 10 min before (baseline), as well as 5 and 10 min after, intravenous administration of 1 mg of glucagon chloride (Novo Nordisk). Statistical analysis was performed by ANOVA test, Bonferroni t test and Spearman rank correlation test. Results - No significant differences were found in mean basal PFV of group 1 (19.4 2.4 cm/sec), group 2 (20.1 3.6 cm/sec) and group 3 (17.5 3.7 cm/sec) (p > 0.05). Five minutes after glucagon injection, all the three groups showed a significant increase in PFV (25.6 4.8,23.7 4.0 and 19.5 5.0 cm/sec, respectively; p < 0.05 vs baseline). The peak increase in PFV after glucagon injection was significantly higher in group 1 (7.9 3.7 cm/sec; 40.7% of basal value) than in group 2 (4.5 3.9 cm/sec; 22.4%) (p < 0.05) and in group 3 (2.7+2.3 cm/sec; 15.4%) (p < 0.05). A significant (p< 0.001) inverse correlation was also found between the patients fibrosis scores and peak increments of PFV induced by glucagon. Conclusions - In some patients with chronic HCV infection, Doppler sonography measurement of PFV after glucagon injection can be useful, in combination with other non invasive ultrasound investigations, both in staging of liver disease and in monitoring the progression of liver histological damage.

Comparison of treatment with two different doses of leukocyte interferon alpha in patients with chronic hepatitis C

BACKGROUND/AIMS

This study was carried in order to investigate whether human leukocyte interferon-alpha administered for 12 months at two different dosages, improves long-term responses in chronic hepatitis C and to see whether pre-treatment gamma-glutamyl transpeptidase values help to predict the clinical response to Interferon.

METHODOLOGY

Forty-five patients were treated for 12 months with natural Interferon-alpha: 3 MU (group A: 31 cases); 6 MU (group B: 14 cases). Biochemical and virological responses were monitored during treatment and follow-up.

RESULTS

Alanine aminotransferase was normalized in 58.1% (Group A) and 54.5% (Group B) of patients by the end of the treatment. Due to side effects 3 patients had to discontinue treatment. During follow-up, remission was maintained in 30.8% and 45.4% of patients respectively (p = 0.046). After 12 months of therapy, respectively 46.7% and 45.4% of patients with complete biochemical response, cleared virus from serum, as did, among long-term responders, 3/8 and 3/4 evaluated patients. Independently of dosage, a complete response was found more often in patients with normal pre-treatment gamma-glutamyl transpeptidase than in those with pre-treatment abnormal values.

CONCLUSIONS

High dosage of IFN alpha was associated with a significantly greater rate of sustained biochemical response and with a better chance of viremia becoming negative. Pre-treatment gamma-glutamyl transpeptidase was able to predict the outcome of the treatment.

Radiological changes and circulating immune complexes in patients with urinary schistosomiasis

The degree of infection and the urographic picture was correlated to the presence and level of circulating immune complexes (CICs) in 69 patients affected by urinary schistosomiasis. Patients were divided into 2 groups: those eliminating less and those eliminating more than 25 eggs/10 ml of urine. Radiological changes in the urinary tract were present in 67% of patients, the most frequent finding being single or multiple filling defects in the bladder. CICs were present in 39 patients. A positive correlation was found between the presence and level of CICs and the output of Schistosoma haematobium eggs, as well as between the presence of CIC and single or multiple filling defects of the bladder. Our findings indicated that CICs were present in patients with urinary schistosomiasis, but the different incidence in patients with a large egg output and radiological filling defects suggests a possible pathogenic role only in the earlier phase of the infection.

Immunological alterations associated with recurrent herpes simplex genitalis

Immunological studies on 12 patients with culture-proven frequently recurrent herpes simplex genitalis were performed. All the patients were evaluated at three time intervals, initially without lesions and/or within 24 hr of lesion onset (acute illness); Days 5-7 from onset and after healing (convalescence); and between recurrences (quiescence). During the first 24 hr of lesions there was a decreased number of helper (CD4+) and an increased number of suppressor/cytotoxic (CD8+) cells with a resultant decrease in the CD4/CD8 ratio. An increased proportion of CD8+ cells coexpressing the CD11 marker (suppressor cells) was noted and correlated with a low proliferative response to HSV-2 antigens. Both the NK cells (CD16+) and the NK cell activity versus HSV-2-infected targets and the K562 cell line were decreased. Five to seven days after onset the number of CD8+ cells remained increased, although the expression of CD11 marker was decreased, indicating that the majority of CD8+ cells were cytotoxic (i.e., CD8+CD11-). At this time, the lymphoproliferative response to HSV-2 antigens and NK cell activity increased, correlating both with the number of CD16+ cells and with the expression of HLA-DR on this subset. In the interval between two recurrences, no significant alteration in any of the above immunological parameters was observed.

Detection of parasite related antigens associated with conglutinin binding immune complexes in patients with Schistosoma haematobium

An ELISA assay was designed to detect the presence of parasite related antigens associated with circulating immune complexes in patients affected by urinary schistosomiasis. The assay makes use of bovine conglutinin as the immune complex recognition unit and of human anti-Schistosoma antibody as the antigen recognition unit. Using this method we showed that 10 of 15 (67%) patients with a positive polyethylene glycol assay had circulating immune complexes in which parasite antigens could be detected.

"Anti-Ia reactivity in sera from patients with chronic active hepatitis (CAH)"

Anti-Ia reactivity in sera from patients with chronic active hepatitis (CAH) were characterized by determining cross-reacting specificities with the antigen defined by anti-Ia monoclonal antibody (MoAb) and by studying the effect of CAH sera on the autologous mixed leukocyte reaction (MLR). Preincubation with autoimmune CAH sera lowered the percentage of Ia+ non-T cells stained by anti-Ia MoAb. HBsAg+ve/HBeAg+ve sera did not exert any blocking activity while 4 out of 11 HBsAg+ve/anti-HBe+ve sera exerted a significant blocking effect. Preincubation of cells with normal human serum (NHS) plus aggregated IgG did not block the binding of MoAb anti-Ia. Sera from patients with autoimmune or HBsAg+ve/anti-HBe+ve CAH, that blocked the binding of anti-Ia MoAb to Ia positive target cells by more than 20%, clearly inhibited the autologous mixed lymphocyte reaction (MLR). Both IgG and IgM fractions obtained by affinity chromatography from CAH sera inhibited the autologous MLR and blocked the binding of anti-Ia antibody to Ia positive target cells. A significant positive correlation (p less than 0.001) between serum anti-Ia reactivity and serum liver membrane antibodies (LMA) was observed. In 4 "autoimmune" CAH patients, steroid treatment induced a dramatic decrease in the anti-Ia reactivity.

Peripheral blood mononuclear cells and regulatory T cells in acute viral hepatitis

During acute viral hepatitis, we observed a significant decrease in OKT4/OKT8 ratio with a significant increase in the OKT8 positive subset in acute type B and non-A-non-B hepatitis. This altered ratio persisted in type B for a long time until HBsAg antibody became detectable, while it soon returned to normal in type A and non-A-non-B hepatitis. In the majority of acute hepatitis the altered ratio is because of an increase and not to a decrease in the whole T cell population, as described in chronic HBV infection. The number of HNK-1 positive cells remained raised during the recovery phase of type B and non-A-non-B hepatitis, a finding consistent with the hypothesis that NK cells play a role in the host defence against B and non-A-non-B virus infections. Serum beta 2-microglobulin concentrations were increased only in acute hepatitis B and non-A-non-B where immunological mechanisms are suspected to be involved, and showed a good correlation with the population of activated OKIa positive cells.

Follow-up of circulating immune complexes in the course of acute viral hepatitis, and correlation with serologically relevant parameters

Type A, type B and type non-A, non-B hepatitis patients were followed up. Several parameters were checked at ten day intervals. Circulating immune complexes (CIC) were detected in a large percentage of patients by using the PEG test and an assay that makes use of bovine conglutinin (K) as recognition unit, and an enzymatically labelled immune complex as the probe. The decrease in the mean level of CIC in the patients correlated with the decrease in serum transaminases and bilirubinaemia in type A and type B hepatitis. Although the pattern of the mean values of the two assays was similar for type A and type B hepatitis, when the two CIC assays were compared for each patient, no significant correlation was found. In light of these and previous results, the necessity for performing CIC monitoring with more than one assay is also discussed.

[Behavior of gamma-glutamyltranspeptidase in acute viral hepatitis]

The value of serum gamma-glutamyltransferase activity has been serially evaluated in 63 patients with acute viral hepatitis at four different periods of the disease (i.e. 0-10, 10-20, 20-30, 30-40 days from the onset of symptoms). The values of serum alanine-aminotransferase, serum alkaline phosphatase and total bilirubin have been evaluated in the same patients at the same period of time. At the first determination the gamma-glutamyltransferase activity was high in acute viral hepatitis, independently from aetiology (A, B, non-A, non-B), although the single values recorded in acute viral hepatitis type non-A, non-B, were higher than those observed in the other types. This activity exhibited a monoesponential pattern of decrease in all types of acute viral hepatitis; and it was still found high in the recovery phase when the others biohumoral indices (alanine-aminotransferase, alkaline phosphatase, total bilirubin) reached a normal level. Therefore gamma-glutamyltransferase activity could be considered of importance in the follow-up of acute viral hepatitis patients, although strictly in conjunction with alanine-aminotransferase, alkaline phosphatase determination.

Incidence of antibodies against rabbit liver specific lipoprotein (RLSP) in chronic active hepatitis

In chronic active hepatitis (CAH) evidence exists that circulating autoantibodies against liver specific lipoprotein (LSP) could play a role in the development of hepatocellular injury. We evaluated the presence of autoantibodies in CAH against LSP using rabbit LSP, as antigen in a radioimmunoprecipitation test. Fifty-one patients with histologically diagnosed CAH were investigated. Among these 16 were HBsAg+, 15 were HBsAg-/anti-HBc+, 10 were non-A, non-B, 10 were autoimmune CAH. Anti-LSP were detected in six of 16 (37%) HBsAg+ (mean titre of 1:198); four of 15 (33%) HBsAg-/anti-HBc+ (mean titre of 1:246); two of 10 (20%) non-A, non-B (mean titre of 1:185); seven of 10 (70%) autoimmune CAH (mean titre of 1:307). No correlation was evident between the titre of anti-LSP and the values of AST, bilirubin or IgG. The findings seem to be consistent with the following conclusions: (a) CAH patients develop an humoral immune response to determinants in LSP which are not species specific. This is further evidence that rabbit LSP could be considered a suitable alternative to the human preparation in evaluation of autoimmunity in CAH and (b) the different behaviour of anti-LSP in patients with viral CAH (B, non-A, non-B) in respect of patients with autoimmune CAH suggests a variable importance of these antibodies in the mechanism of ongoing liver cell injury according to the various types of CAH.

Cell-mediated cytotoxicity to rabbit liver-specific lipoprotein in chronic active hepatitis

Cell-mediated cytotoxicity to 51Cr-labelled avian red blood cells coated by rabbit liver-specific lipoprotein was evaluated in 27 patients with untreated chronic active hepatitis (11 were HBsAg-positive). A significantly increased cytotoxicity was recorded in 10 of the 11 patients with HBsAg-positive chronic active hepatitis and in 13 of the 16 HBsAg-negative patients. The addition of rabbit LSP to the test system reduced to normal the cytotoxicity index in all the positive cases. Moreover, in order to evaluate the organ-specificity of cytotoxicity to rabbit LSP-coated cells, we added to the test system a macromolecular kidney protein fraction which was unable to block the cytoxicity in any of the positive cases. In 12 selected cases, which had previously shown an increased cytotoxicity to rabbit LSP-coated red blood cells, the incubation of their lymphocytes at 37 degrees C for 30 min in a plastic Petri dish resulted in the abolition of cytotoxicity. Our findings seem to indicate that cell-mediated cytotoxicity to LSP can also be detected with an antigen, not prepared from human liver. This is a further evidence that patients with chronic active hepatitis develop an immunological reactivity to not species-specific antigenic determinants in LSP.

Immune response to rabbit liver-specific lipoprotein in acute viral hepatitis

A serial prospective study of cell-mediated immunity to rabbit liver-specific lipoprotein (RLSP) has been done in 26 patients with acute viral hepatitis (AH) (18 HBsAg+ and eight HBsAg-) using a lymphocyte transformation test. An increased stimulation index was recorded in 56% of HBsAg+ cases and in 63% of the HBsAg- group at the first determination within 2 weeks of presentation. A progressive return to normal values was observed during the course of the disease. In one patient, however, the stimulation index remained high at 6 months after presentation and liver biopsy showed the appearance of chronic active hepatitis. Results within the normal range of values were observed when a macromolecular kidney protein fraction was used as antigen: further evidence of an organ-specific component in RLSP preparation to which the immune response seems to be directed. These findings demonstrate the existence of a common and time-limited sensitization to RLSP in acute viral hepatitis irrespective of HBsAg status. It is suggested that RLSP may be a useful alternative to human LSP in evaluating immune reactions in liver diseases.

[Direct and induced lymphocytotoxicity to rabbit hepatocytes in chronic active hepatitis]

The lymphocytotoxicity to rabbit hepatocytes either direct or serum induced was evaluated in chronic active hepatitis (CAH). We obtained the following results: a) the direct lymphocytotoxicity obtained in CAH patients significantly correlated with the cytotoxicity induced by CAH sera in normal lymphocytes; b) no difference could be recorded in CAH HBsAG positive or negative; c) the target antigen of the immune reaction seems to be the liver specific lipoprotein.

Lymphocyte transformation test with rabbit liver specific lipoprotein (RLSP) in chronic active hepatitis

Cellular sensitization to rabbit liver specific lipoprotein (RLSP) has been investigated using a lymphocyte transformation test in patients with chronic active hepatitis (CAH). A stimulation index greater than 2 was recorded in twenty out of twenty-five cases (eight of ten HBsAg positive and twelve of fiteen HBsAg negative) while values were lower than 2 in all the normal subjects. These results confirm the finding of sensitization to LSP in chronic active hepatitis irrespective of HBsAg status and show that rabbit LSP can be used as an alternative to the human antigen in the lymphocyte transformation test, and is further evidence that this liver membrane lipoprotein has antigenic determinants which have species-cross-reactivity.

[Hepatitis and drug addiction: clinical and immunological studies]

The association drug addiction-hepatitis has so increased in recent years to represent a social epidemiological and clinical problem all over the world. Although the clinical picture of hepatitis is already well defined in drug-abusers, it remains to be completely understood the mechanism responsible for the significant incidence of progression from acute to chronic hepatitis in this population. The viral infection, the drug itself, the drug contaminants, the immunological defects (cellular and/or humoral) may be considered as possible contributing factors to this event. For this reason the Authors have performed an immunological study either in a group of drug-abusers with acute and chronic hepatitis, or in a group of 82 "asymptomatic" drug addicts without a history of liver diseases. The results of this study are the following: - In all the drug-addicts considered there is a common contact with virus B. - There are significant alternations of the cellular and humoral immunity in drug-addicts with acute and chronic hepatitis. - In the "asymptomatic" group the humoral immunity is slightly altered (hyper IgM, circulating immunocomplexes), while normal the cellular response. All these findings are critically evaluated also in respect with the new immunopathological mechanisms of hepatitis B.

[Hepatitis A and hepatitis B. Clinical, epidemiological and differential immunological elements]

The Authors have already related in various papers the results of their research on humoral and cellular immunity in the course of viral hepatitis in relation to the behaviour of HBsAg determined with various methods and recently with the radio-immune assay. Since the high sensitivity of this latter technique consents a sufficiently precise differentiation of hepatitis into HBAg-positive (hepatitis B) and HBAg-negative (hepatitis A), the Authors have intended studying in this work the eventual clinical epidemiological and immunological differences between the two types of hepatitis, analyzing the results of their previous studies, extending the case data and gathering numerous other personal observations, clinical and laboratory, not yet published. The study was limited to 136 patients with viral hepatitis in wwhich the test for HBsAg was effected with RIA: of these 58 were HBAg+ and 78 HBAg-. Initially is discussed the incidence of two types of hepatitis in relation to age and sex and then the comparative incidence between them of the various routes of contagion. Particularly emphasized is the possibility of direct transmission of HBAg+ hepatitis, often responsible for infection within the family. The comparative determination of transaminases, bilirubin, immunoglobulins and complement has revealed some interesting variations in the behaviour of the two types of hepatitis. Instead, cellular immunity, studied by the rosette E technique, appeared depressed in the initial phase of sickness in both types of hepatitis. Space is dedicated to the behaviour of HBsAg in acute HBAg+ hepatitis in relation to the immunoglobulins and complement and in relation to the normalization of the transaminases and bilirubinemia. After a few brief observations on the frequent appearance of a joint symptomatology in the course of viral hepatitis, particularly in the HBAg+ form, the Authors report the data relative the evolution of the hepatitis cases examined. The percentage of a complete cure are about equal between hepatitis A and hepatitis B even recovery is significantly faster in the first type of hepatitis (HBAg-).