A study of the evolution of specific and non-specific immune complexes in acute hepatitis B and chronic hepatitis

Molecular mechanisms underlying occult hepatitis B virus infection

Chronic hepatitis B virus (HBV) infection is a complex clinical entity frequently associated with cirrhosis and hepatocellular carcinoma (HCC). The persistence of HBV genomes in the absence of detectable surface antigenemia is termed occult HBV infection. Mutations in the surface gene rendering HBsAg undetectable by commercial assays and inhibition of HBV by suppression of viral replication and viral proteins represent two fundamentally different mechanisms that lead to occult HBV infections. The molecular mechanisms underlying occult HBV infections, including recently identified mechanisms associated with the suppression of HBV replication and inhibition of HBV proteins, are reviewed in detail. The availability of highly sensitive molecular methods has led to increased detection of occult HBV infections in various clinical settings. The clinical relevance of occult HBV infection and the utility of appropriate diagnostic methods to detect occult HBV infection are discussed. The need for specific guidelines on the diagnosis and management of occult HBV infection is being increasingly recognized; the aspects of mechanistic studies that warrant further investigation are discussed in the final section.

Molecular mechanisms underlying occult hepatitis B virus infection

Chronic hepatitis B virus (HBV) infection is a complex clinical entity frequently associated with cirrhosis and hepatocellular carcinoma (HCC). The persistence of HBV genomes in the absence of detectable surface antigenemia is termed occult HBV infection. Mutations in the surface gene rendering HBsAg undetectable by commercial assays and inhibition of HBV by suppression of viral replication and viral proteins represent two fundamentally different mechanisms that lead to occult HBV infections. The molecular mechanisms underlying occult HBV infections, including recently identified mechanisms associated with the suppression of HBV replication and inhibition of HBV proteins, are reviewed in detail. The availability of highly sensitive molecular methods has led to increased detection of occult HBV infections in various clinical settings. The clinical relevance of occult HBV infection and the utility of appropriate diagnostic methods to detect occult HBV infection are discussed. The need for specific guidelines on the diagnosis and management of occult HBV infection is being increasingly recognized; the aspects of mechanistic studies that warrant further investigation are discussed in the final section.

Serological and immunohistochemical studies on porcine-serum-induced hepatic fibrosis in rats

We previously reported that the strain difference in the development of porcine-serum (PS)-induced rat hepatic fibrosis was closely related to the difference in the mode of MHC class-II-related genes expression. This study was carried out to clarify the serological and immunohistochemical changes in this hepatic fibrosis model. Six-week-old male Brown Norway (BN) and Wistar rats were injected with 0.5 ml of sterile PS twice a week for up to 8 weeks. The serum levels of PS-specific IgG1, IgG2a, and IgM were elevated more prominently in BN rats than Wistar rats. In the liver, significant increases in the numbers of PS-, OX-6 (RT1.B)-, CD4-, CD8, ED1-, and ED2-positive cells occurred earlier in BN rats than Wistar rats. At 8 weeks, deposition of PS and immunoglobulins was observed in hepatic fibrous septa and renal glomerular mesangium, and IgG1- and IgG2a-positive cells were found in the white pulp of the spleen. The present results suggest that humoral immunity probably regulated by MHC class II molecules and inflammatory cells may be involved in PS-induced hepatic fibrosis in rats.

The absence of antibodies to malaria and human immunodeficiency virus, and the presence of hepatitis B surface antigen as diagnostic markers of rheumatoid arthritis

Rheumatoid factor is of limited value in the diagnosis of rheumatoid arthritis (RA) in West Africa. Consequent upon previous findings, we have studied the role of the absence of antibodies to malaria and human immunodeficiency virus (HIV) as well as the presence of the hepatitis B surface antigen (HBsAg) as diagnostic markers of rheumatoid arthritis in West Africa. We have found a significant association (p < 0.001) between RA and titre of HBsAg, but only between RA and malaria (p < 0.05) when sera with low malaria antibodies were studied. No correlation between either HBsAg or malaria and rheumatoid factor was found and no RA patient was either HIV-1 or HIV-2 positive.

An investigation on rheumatoid factor of different immunoglobulin classes in hepatitis B virus carriers

Rheumatoid factor (RF) is known to be present very frequently in HB virus carriers. When RF was assayed in 140 asymptomatic carriers by agglutination method, 20.0% were found to be positive, whereas 2.7% in the controls (p less than 0.01). ELISA for detection of RF isotypes showed RF in carriers to be almost IgMRF only. IgMRF showed a tendency to react more readily to human IgG rather than to rabbit IgG. The incidence of IgMRF positivity was higher among anti-HBe antibody-positive carriers than among anti-HBe antibody negative ones, but the difference between the two populations was not significant. However, the incidence of IgMRF positivity in the group showing hepatic dysfunctions was found to be significantly higher than in the group with normal hepatic functions.